GARN® WHS-2000 Wood Hydronic Gasification Boiler Design Manual

GARN® WHS-2000 Wood Hydronic Gasification Boiler Design Manual
GARN®
System Design Manual
Hot Water Supply
2” FPT
Hot Water Return
1-1/2” MPT
Hydronic System Design Manual
March 2013
1
The GARN® unit, all related heating equipment (including pumps, piping, fan coils, hot water baseboard, radiant
floor heating systems, etc) and all electrical equipment (including power wiring, controls, control wiring, back up
electric heating, etc) must be installed by a qualified installer or competent licensed personnel in strict compliance
with all Federal, State and local codes. All electrical equipment, devices and wiring installed with the GARN® unit
must be UL listed. Installer to supply and install all code required electrical over current and disconnect devices.
Table of Contents
A.
SYMBOLS, ABBREVIATIONS, and safety symbols: .......................................................................................... 4
B.
PROMOTING CONSERVATION AND EFFICIENCY BEFORE ANYTHING ELSE: ..................................................... 5
PROBLEMS WITH IMPROPERLY COMBUSTED FUEL: .................................................................................................5
HEATING A SWIMMING POOL: .................................................................................................................................5
C.
RULES OF THUMB FOR AN INITIAL ESTIMATE OF EQUIPMENT SIZE ............................................................... 6
COMMERCIAL HEAT LOSS: ........................................................................................................................................6
RESIDENTIAL HEAT LOSS EXCLUDING VENTILATION: ................................................................................................6
RESIDENTIAL VENTILATION: ......................................................................................................................................6
RESIDENTIAL DOMESTIC WATER HEATING: ..............................................................................................................7
HOT TUB HEATING: ...................................................................................................................................................7
RADIANT FLOOR HEATING: .......................................................................................................................................7
FORCED AIR HEATING: ..............................................................................................................................................8
HOT WATER BASEBOARD HEATING: .........................................................................................................................9
GLYCOL CORRECTION FACTORS AND FREEZE PROTECTION TABLES:......................................................................10
The difference between freeze and burst protection: (DOW Chemical)..............................................................11
PUMP LAWS AND FAN LAWS: .................................................................................................................................11
D.
PIPING AND PUMP SIZING ........................................................................................................................... 12
PIPING DESIGN AND CALULCATION GUIDELINES ....................................................................................................12
EQUIVALENT FEET OF PIPE FOR SCREWED FITTINGS AND VALVES .....................................................................12
EQUIVALENT FEET OF PIPE FOR PEX FITTINGS ....................................................................................................13
Flow and heat capacity @ 4' of head loss per 100' of pipe length ......................................................................13
Flow and heat capacity @ 6' of head loss per 100' of pipe length ......................................................................14
PRESSURE LOSS CHARTS: STEEL, COPPER, PEX ....................................................................................................15
PIPING INSTALLATION AND HOOKUP GUIDELINES .................................................................................................16
PLUMBING WITH COPPER: ..................................................................................................................................16
PLUMBING WITH STEEL: .....................................................................................................................................16
CALCULATION OF NET POSITIVE SUCTION HEAD FOR PUMPS ...............................................................................17
UNDERGROUND PIPING:.........................................................................................................................................19
DRY AREA BURIED PIPING DIAGRAM: .................................................................................................................19
MOIST AREA BURIED PIPING DIAGRAM: .............................................................................................................20
ROADWAY AND PARKING LOT BURIED PIPING DIAGRAM: .................................................................................21
PUMP SELECTION AND INSTALLATION GUIDELINES: ..............................................................................................21
E.
SYSTEM DISTRIBUTION CONNECTION AND SCHEMATICS ............................................................................ 23
ZERO PRESSURE, FIXED TEMP - PRIMARY ONLY PUMPING: ...................................................................................23
ZERO PRESSURE, FIXED SUPPLY TEMP – PRIMARY SECONDARY PUMPING: ..........................................................24
ZERO PRESSURE, MULTIPLE ZONE – PRIMARY SECONDARY PUMPING: .................................................................25
CONNECTING TO AN EXISTING PRESSURIZED OR GLYCOL TREATED DISTRIBUTION SYSTEM: ...............................27
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PRESSURIZED, FIXED SUPPLY TEMP – CONSTANT SPEED PUMPING ......................................................................28
PRESSURIZED, FIXED SUPPLY TEMP – VARIABLE SPEED PUMPING.........................................................................29
F.
SYSTEM COMPONENT CONNECTION AND SCHEMATICS .............................................................................. 30
CONNECTION TO FORCED AIR FURNACE: ...............................................................................................................30
FORCED AIR GUIDELINES:....................................................................................................................................30
COIL SELECTION...................................................................................................................................................31
HIGH LIMIT SWITCH (DUCT STAT) .......................................................................................................................31
BLOWER SPEED AND CFM ADJUSTMENT ............................................................................................................31
CONNECTION TO HOT WATER BASEBOARD SYSTEM: ............................................................................................32
HOT WATER BASEBOARD GUIDELINES ...............................................................................................................32
NEW CONSTRUCTION .........................................................................................................................................33
CONVERTING AN EXISTING BASEBOARD SYSTEM ...............................................................................................33
CONNECTION TO HYDRONIC RADIANT FLOOR SYSTEM: ........................................................................................34
RADIANT FLOOR GUIDELINES: ............................................................................................................................34
CONNECTION TO AN EXISTING PRESSURIZED SYSTEM ...........................................................................................35
WATER TO WATER FLAT PLATE HEAT EXCHANGERS ...........................................................................................36
CONNECTION TO AN ELEVATED SYSTEM ................................................................................................................37
CONNECTION TO DOMESTIC HOT WATER ..............................................................................................................37
SOLAR INTERFACE: ..................................................................................................................................................39
G.
BACKUP HEATING WITH THE EXISTING SYSTEM OR ELECTRIC ...................................................................... 40
H.
EXAMPLE PROBLEM – HOUSE WITH REMOTE POLE BARN/WORKSHOP ...................................................... 41
EXAMPLE PROBLEM SETUP: ....................................................................................................................................41
HOUSE DESIGN:.......................................................................................................................................................41
MAIN FLOOR DESIGN: .........................................................................................................................................41
BASEMENT LEVEL DESIGN: ..................................................................................................................................43
SIZE THE main floor HOUSE PUMP..........................................................................................................................43
SIZE THE BASEMENT PUMP ....................................................................................................................................44
DISTRIBUTION PIPE AND PUMP SIZING ..................................................................................................................44
SIZE DISTRIBUTION PUMP.......................................................................................................................................45
POLE BARN DESIGN .................................................................................................................................................45
SIZE POLE BARN PUMP ...........................................................................................................................................46
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A. SYMBOLS, ABBREVIATIONS, AND SAFETY SYMBOLS:
ABBREVIATIONS
SYMBOLS
BTUH
BTU’s per hour
Pump
EWT
Entering Water Temperature
Strainer
FPS
Feet per second
Flow Arrow
FPT
Female Pipe Thread
Mixing Valve
GPM
Gallons per minute
Isolation Valve
HWS/HWR Hot Water Supply/Hot Water Return
Flange
MBH
MBTU’s (1,000 BTU) per hour
Thermometer
MMBH
MMBTU (1,000,000 BTU) per hour
Temperature Sensor
MPT
Male Pipe Thread
Check Valve
NPT
National Pipe Thread
Drain
OD
Outdoor
Connect to Existing
RWT
Return Water Temperature
A notice provides a piece of information to make a procedure easier or clearer.
A caution emphasizes where equipment damage might occur. Personal injury is
not likely.
A warning emphasizes areas where personal injury or death may occur but is not
likely. Property or equipment damage is likely.
A danger emphasizes areas or procedures where death, serious injury, or property
damage is likely if not strictly followed
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B. PROMOTING CONSERVATION AND EFFICIENCY BEFORE
ANYTHING ELSE:
PROBLEMS WITH IMPROPERLY COMBUSTED FUEL:
Improperly combusted wood fuel emissions are toxic to humans and animals. These emissions include:
finely atomized liquid oils (creosote), very fine particulates, aromatic hydrocarbons, polycyclic organic
matter, carbon dioxide, and carbon monoxide. In fact, population densities in suburban and urban
locations create significant local air shed pollution issues that essentially preclude the use of coal, wood
and other fuels. Complete combustion reduces these by-products significantly.
BUT! Remember this: Eliminating fuel usage is the same as burning fuel with absolutely zero emissions,
impossible for any fuel, even natural gas! A well designed and constructed energy efficient building can
reduce heating demand and fuel usage by at least half or more when compared to a “code built house.”
By following the simple suggestions below, you will reduce fuel usage and annual fuel bills, create a
comfortable and healthy environment for the occupants, contribute to a healthier local air shed, and
realize a reasonably quick return on investment.










Install good insulation and caulking.
Install double glazed, argon filled energy efficient windows (or better).
Install insulated thermally efficient doors and storm doors, with good quality weather stripping.
Install an air-to-air heat exchanger (heat recovery ventilator) to provide ventilation.
Insulate and caulk all rims joists.
Insulate basements walls from floor to ceiling with methods that prevent the formation of mold
and mildew.
Utilize passive solar techniques whenever possible.
Install water saving toilets, showers and faucets throughout.
If you have access to natural gas, use a high efficiency natural gas condensing furnace or boiler
to provide space and domestic water heating. Don’t burn wood unless you want to.
Install only high SEER air conditioning equipment with variable speed fans to effectively control
indoor relative humidity.
HEATING A SWIMMING POOL:
This is best accomplished with solar heating and an evaporation prevention blanket. Solar heating has
proven cost effective, dependable and efficient for many years in many countries. Solar heating is
efficient in almost every area of the US. Most people do not realize that a swimming pool requires a
heater that may be several times the size and capacity of their residential space heater. However, during
the spring, summer and fall the amount of energy required to heat a pool is easily provided by solar
panels.
For more information on solar pool heating products visit:
http://www.heliocol.com/
http://www.aetsolar.com/
http://www.h2otsun.com/
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C. RULES OF THUMB FOR AN INITIAL ESTIMATE OF
EQUIPMENT SIZE
The following are approximate values that may be used to estimate the size of the primary wood
heating equipment. Once a project is given the “go ahead” an exact heat loss should be calculated
according to ASHRAE Fundamentals or Manual J methods to ensure correct sizing. Over-sizing
equipment leads to excessive first cost, inefficient operation, and increased emissions.
There are software packages that calculate an accurate heat loss value based on the detailed
construction of the building. An example is Elite Software’s RHVAC program. DECTRA CORPORATION
can run an in-depth heat loss analysis for a fee.
To learn more about Elite Software RHVAC or to purchase a software license visit:
http://www.elitesoft.com/
COMMERCIAL HEAT LOSS:
Calculating the heat loss for commercial buildings can be more complicated than for residential
structures because the building type and application vary significantly. The easiest way to get a handle
on heat loss figures for a commercial facility is to use a computer software package. A good commercial
heat loss packages is Elitie Software’s CHVAC program.
To learn more about Elite Software CHVAC or to purchase a software license visit:
http://www.elitesoft.com/
RESIDENTIAL HEAT LOSS EXCLUDING VENTILATION:
Old/Poorly Insulated House
Uninsulated basement
Newer House
Insulated Basement
Energy Efficient House
Insulated Basement
25 to 35
13 to 24
8 to 15
18 to 30
10 to 20
8 to 12
Above Grade Floor
Area (BTUH/sq. ft.)
Below Grade Floor
Area (BTUH/sq. ft.)
RESIDENTIAL VENTILATION:

In newer, tighter energy efficient houses, mechanical ventilation is required at a generally
accepted rate of 15 cfm per person. The following should be added to the heat loss for newer
houses, but not added to the heat loss of older houses (unless the older house has been
reinsulated and tightly sealed against air leakage).
Heat Recovery Ventilator Not Used Heat Recovery Ventilator Used
6,000 BTUH/person
3,000 BTUH/person
For more information on HRV products visit:
http://www.vanee-ventilation.com/
http://residential.fantech.net/
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RESIDENTIAL DOMESTIC WATER HEATING:

Maximum delivered water temperature must be 120°F or less. An anti-scald valve is required by
most codes on the discharge of the water heater. Maintain the water heater at 140°F or higher
to kill bacteria and virus.
Normal Family of 4, Modest Size House Larger Family in Larger House
40,000 BTUH recovery rate
75,000 BTUH recovery rate
50 to 75 gallon water heater
100 to 120 gallon water heater
HOT TUB HEATING:

Small (7’ to 10’ square x 4’ deep) insulated outdoor hot tubes with an insulated cover generally
require only 2,000 to 2,500 BTUH to maintain temperature when the tub is covered at outdoor
temperatures of –20°F. It is assumed that the hot tub is used for brief periods (say 1 to 2 hours
per day) during which time the evaporative cooling of the water’s surface is the primary heat
loss and may equal 6,000 to 9,000 BTUH. Any heat exchanger used to heat a hot tub should be
sized for this larger value.
RADIANT FLOOR HEATING:



Normal temperature drop is 10°F to 20°F per tube length.
Try not to exceed a floor surface temperature of 85°F (comfort and finish materials limitations).
Always insulate beneath a radiant floor system whether on or above grade. 2” of blue, pink,
green or yellow board (not white bead board or polyurethane) is strongly recommend for slab
on grade concrete slabs and R13 is the minimum recommended for upper level wood floors.
Maximum Flow
1/2” PEX Tubing
5/8” PEX Tubing
0.575 gpm
1 gpm
Maximum Length of
Individual Tube Run
300 ft
450 ft
Typical Maximum Number
of Tubes per Manifold
8
12
GARN® recommends the use of oxygen-barried, PEX-a tubing. For more information visit:
www.mrpexsystems.com
www.uponor-usa.com
www.comfortprosystems.com
OXYGEN-BARRIED PEX-A TUBING IS NECESSARY IN ORDER TO MINIMIZE THE
POTENTIAL FOR CORROSION.
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FORCED AIR HEATING:
DO NOT MOUNT A HOT WATER COIL ON THE RETURN SIDE OF THE FURNACE.
Warm air will be flowing over the blower motor and may not provide sufficient
motor cooling. Doing so will void the furnace warrantee and the UL listing of the furnace.
DO NOT MOUNT A HOT WATER COIL IN SYSTEMS SERVED BY A HIGH EFFICIENCY
CONDENSING FURNACE. Doing so will void the furnace warrantee and the UL
listing of the furnace and create the potential for flue damage and a building fire.




Size a coil that increases the air-side pressure drop by only 0.25” to 0.33” WC. Increase blower
RPM to offset this increased static pressure and maintain CFM. Select a coil that will provide a
supply air temperature of 110°F or slightly greater. Code limit is 140°F.
Pipe all coils in a counter flow pattern. The “normal” range of water temperature drop through
a coil is 8°F to 20°F.
Mount hot water coils (flat and A-type) on the discharge side of the furnace. In almost all cases
the coil will be physically larger than the existing supply air plenum. The plenum size will have
to be increased. Sheet metal work must be designed and fabricated in accordance with
SMACNA guidelines.
If the furnace is more than 12 years old, consider installing a new unitized fan coil unit that
provides a motorized fan, filter, hot water heating coil, DX cooling coil and controls all within
one insulated sheet metal unit. Such units are manufactured to replace an existing residential
furnace and reasonably match the existing furnace’s overall dimensions. When selecting a unit,
make sure to apply a correction factor (if necessary) for the hot water coil output at the entering
water temperature (EWT) expected in the new system versus the EWT at the manufacturer’s
rated output (see water temperature table in the Hot Water Baseboard Heating section of this
manual).
For more information on unitized fan coil units visit:
http://www.firstco.com/
http://www.magicaire.com
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HOT WATER BASEBOARD HEATING:

HWBB output ratings are based on 1 gpm to 4 gpm flow rate and an EWT of 215°F for most ¾”
and 1” standard sizes. The following correction factors are to be applied to the 215°F ratings
when a lower EWT is used:
Water Temperature Correction Factors (entering air temperature = 65°F)
100 110 120 130 140 150 160 170 180 190 200 210 215
Correction Factor 0.13 0.19 0.25 0.31 0.38 0.45 0.53 0.61 0.69 0.78 0.86 0.95 1.00
Supply Water Temperature (°F)
EXAMPLE:
The above table can also be used with baseboard rated at an EWT different 215°F. For example, if an
EWT of 140°F is to be used, and the baseboard manufactured rated its baseboard at a an EWT of
180°F, then the appropriate correction factor is:



Normal temperature drop is 10°F to 20°F per HWBB run. GARN® equipment and many nonwood systems today are based on an EWT of 140°F and a RWT of 120°F to take advantage of
condensing boilers.
Combining a radiant floor manifold and PEX tubing with HWBB, can yield individual room control
with a wall mounted, night set back thermostats.
Modern European flat panel wall mounted steel radiators are similar in flow requirements as
HWBB.
For more information on HWBB products visit:
www.sterlingheat.com
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GLYCOL CORRECTION FACTORS AND FREEZE PROTECTION TABLES:
PROPYLENE GLYCOL
FREEZE AND BURST PROTECTION
Temp (°F)
20
10
0
-10
-20
-30
-40
-50
-60
Freeze Protection Burst Protection
(% by volume)
(% by volume)
18%
12%
29%
20%
36%
24%
42%
28%
46%
30%
50%
33%
54%
35%
57%
35%
60%
35%
PROPYLENE GLYCOL
HEAT AND FLOW CORRECTION
PROPYLENE GLYCOL
PRESSURE DROP CORRECTION
% By
Volume
20%
25%
30%
35%
40%
45%
50%
55%
60%
% By
Volume
20%
25%
30%
35%
40%
45%
50%
55%
60%
Heat
Transfer
0.987
0.978
0.969
0.957
0.944
0.928
0.912
0.893
0.873
Pump
Flow
1.013
1.022
1.032
1.045
1.059
1.077
1.096
1.120
1.145
140°F
Solution
1.067
1.078
1.089
1.106
1.122
1.139
1.156
1.172
1.189
100°F
Solution
1.098
1.120
1.141
1.168
1.196
1.228
1.261
1.293
1.326
NOTES:
1. GARN® recommends the use of Propylene glycol because it is not as toxic as Ethylene glycol.
Check with the chemical manufacturer for specific concentration requirements.
2. The “Heat Transfer” correction factors represent the decrease in heat transfer when compared
with 100% water and no change in flow rate. The “Pump Flow” correction factors represent the
increase in flow required to maintain the same heat output rate as 100% water.
3. The “Pressure Drop” correction factors represent the increase in pressure drop of the system
due to the glycol solution as compared to water at the same temperature.
EXAMPLE:
Select a propylene glycol solution for freeze protection of a coil designed for use as an outdoor air
heating coil in Portland, ME. The ASHRAE design heating dry bulb temperature in Portland, ME is -1°F.
By using the above table, a glycol solution of 36% is required for freeze protection.
EXAMPLE:
Let’s say, the outdoor air coil in the previous example is rated for 50,000 BTUH at 140°F EWT, 20° ΔT,
5 GPM. What is the coil’s rated output with a 36% propylene glycol solution? What increase in GPM
is required to maintain the 50,000 BTUH heat output rate? What increase in pressure drop will the
pump see?
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THE DIFFERENCE BETWEEN FREEZE AND BURST PROTECTION: (DOW CHEMICAL1)
Burst protection is required if your heating system/fluid will sit dormant at temperatures below freezing
without being pumped, putting the pipes in danger of bursting. For these situations a slushy mixture is
acceptable, because the fluid will not be pumped through the system. A slushy mixture is one that
contains water and glycol, but as mixture of liquid and frozen ice crystals. Trying to pump fluid
containing ice crystals can result in damage to system components. Since the mixture expands as it
freezes, there must be enough volume available in the system to accommodate the expansion.
Freeze protection is required if your heating system/fluid is going to be pumped at temperatures at or
below the freezing point of the fluid. For example, systems that are dormant for much of the winter,
but require start up during the cold weather, or systems that would be at risk if the power or pump
failed. For these situations, the system must have enough glycol present to prevent any ice crystals
from forming. It generally requires more glycol for freeze protection, keeping the fluid completely
liquid, than it does for burst protection, where a slushy mixture is acceptable.
PUMP LAWS AND FAN LAWS:
Depending on the application, a pump or fan may need to be sped up or slowed down to achieve the
desired function in a heating system. Use the following handy equations to calculate the increase or
decrease in flowrate, pressure, and power consumption based on the original and the new pump or fan
speed (RPM).
PUMPS
(
(
(
FANS
)
(
)
)
)
(
(
)
)
1
https://dow-answer.custhelp.com/app/answers/detail/a_id/5206/~/lttf---burst-protection-vs-freeze-protectionfor-glycol-based-heat-transfer
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D. PIPING AND PUMP SIZING
Correctly sized piping and pumps are necessary for the efficient and safe transport of heated water from
the GARN® WHS unit to the building heating system.
All piping, pumps, wiring and controls, etc must be sized and installed by a
qualified and licensed professional. All items are to be installed in full compliance
with all national, state and local codes. For installations not covered in this
manual contact your local GARN® dealer for design assistance.
PIPING DESIGN AND CALULCATION GUIDELINES
Size all above grade and underground piping per standard industry guidelines:
 Maximum head loss of 4’ to 6’ per 100’ of pipe for energy conservation.
 Maximum velocity of 8’ per second to minimize surface erosion potential in most pipes.
 Maximum velocity of 6’ per second to limit noise.
Incorrect pipe sizing will adversely affect the heating system performance, efficiency and cost of
operation. Undersized piping may cost less to install, but the pump size must be increased, adding
significantly to the pump cost and the cost of operation. Head loss data for a specific pipe or tubing, and
for various fittings is tabulated in manufacturer literature, plumbing manuals, state plumbing codes and
local building codes. A representative sample of the head loss associated with various fittings for copper
or steel is listed below. Recommended flow rates for various pipe materials are tabulated on the next
two pages.
EQUIVALENT FEET OF PIPE FOR SCREWED FITTINGS AND VALVES
NOMINAL PIPE SIZE, INCHES
45 Degree Elbow, Regular
90 Degree Elbow, Long
90 Degree Elbow, Regular
Gate Valve, Open
Ball valve, Full Port, Open
Globe Valve, Open
Tee-Branch Flow
Tee-Line Flow
Strainer
Swing Check Valve
Hydronic System Design Manual
March 2013
(for steel and copper)
1/2
3/4
1
1 1/4
1 1/2
2
0.8
2.2
3.6
0.7
0.3
22.0
4.2
1.7
5.0
8.0
1.3
2.7
5.2
1.0
0.5
29.0
6.6
3.2
7.7
11.0
1.7
3.2
6.6
1.5
0.7
37.0
8.7
4.6
18.0
13.0
2.1
3.4
7.4
1.8
0.8
42.0
9.9
5.6
20.0
15.0
2.7
3.6
8.5
2.3
1.0
54.0
12.0
7.7
27.0
19.0
0.9
2.3
4.4
0.9
0.4
24.0
5.3
2.4
6.6
8.8
12
EQUIVALENT FEET OF PIPE FOR PEX FITTINGS
Nominal pipe size, inches
(brass fittings)
1/2
3/4
1
1 1/4
1 1/2
2
3.0
1.0
2.0
1.0
2.2
0.3
0.8
0.3
3.4
0.2
2.0
0.2
9.6
1.5
8.8
1.6
10.9
2.7
11.6
2.1
11.3
1.4
12.1
1.6
2.3
0.2
0.2
0.8
4.6
0.2
0.2
2.0
10.0
3.8
8.6
11.5
1.8
10.6
-
90 Degree Elbow
Coupling
Tee-Branch Flow
Tee-Line Flow
(EP fittings)
3.7
1.0
1.0
2.3
90 Degree Elbow
Coupling
Tee-Branch Flow
Tee-Line Flow
FLOW AND HEAT CAPACITY @ 4' OF HEAD LOSS PER 100' OF PIPE LENGTH
SIZE
INSIDE DIA.
FLOW, gpm
BTU/HR
10°F ΔT
BTU/HR
20°F ΔT
BTU/HR
30°F ΔT
12,500
15,000
27,500
75,000
135,000
260,000
25,000
30,000
55,000
150,000
270,000
520,000
37,500
45,000
82,500
225,000
405,000
780,000
Oxygen Barriered PEX Tubing
5/8”
3/4"
1"
1 1/4"
1 1/2"
2"
0.574”
0.678”
0.875”
1.280"
1.600"
2.030"
2.5
3
5.5
15
27
52
Type L Rigid Copper Tube - max. vel = 6'/sec for noise; max. vel = 10'/sec for erosion
3/4"
1"
1 1/4"
1 1/2"
2"
0.785"
1.025"
1.265"
1.505"
1.985"
3.5
6.5
12
18
39
17,500
32,500
60,000
90,000
195,000
35,000
65,000
120,000
180,000
390,000
52,000
97,000
180,000
270,000
585,000
4.2
8
17
25
48
21,000
40,000
85,000
125,000
240,000
42,000
80,000
170,000
250,000
480,000
63,000
120,000
255,000
375,000
720,000
Schedule 40 Black Steel Pipe
3/4"
1"
1 1/4"
1 1/2"
2"
0.824"
1.049"
1.380"
1.610"
2.067"
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FLOW AND HEAT CAPACITY @ 6' OF HEAD LOSS PER 100' OF PIPE LENGTH
SIZE
INSIDE DIA.
FLOW, gpm
BTU/HR
20°F ΔT
BTU/HR
30°F ΔT
30,000
45,000
65,000
190,000
340,000
640,000
45,000
67,500
97,500
285,000
510,000
960,000
Oxygen Barriered PEX Tubing
5/8”
3/4"
1"
1 1/4"
1 1/2"
2"
0.574”
0.678"
0.875”
1.280"
1.600"
2.030"
3
4.5
6.5
19
34
64
Type L Rigid Copper Tube - max. vel = 6'/sec for noise; max. vel = 10'/sec for erosion
3/4"
1"
1 1/4"
1 1/2"
2"
0.785"
1.025"
1.265"
1.505"
1.985"
4.2
8.5
15
23
48
42,000
85,000
120,000
230,000
480,000
63,000
127,000
180,000
345,000
720,000
5.5
9.5
19
30
60
55,000
95,000
190,000
300,000
600,000
82,000
142,000
285,000
450,000
900,000
Schedule 40 Black Steel Pipe
3/4"
1"
1 1/4"
1 1/2"
2"
0.824"
1.049"
1.380"
1.610"
2.067"
NOTE: Head loss for different GPMs than those listed in the flow and heat capacity tables can be
ESTIMATED with the following formula:
(
̇
̇
)
For Example, let’s say we want to know the head loss of 3 gpm through ¾” Type L copper. Using the 6’
per 100’ table, the flow rate is 4.2 gpm:
(
) (
)
The above calculations could be approximated as 0.5’ per 100’ or 1’ per 100’ depending on the
experience/discretion of the designer. The above formula is accurate for flow rates +/-20% of those
listed.
For more information on PEX-a pressure drop data visit:
ComfortPro Systems Document Center
Hydronic System Design Manual
March 2013
14
PRESSURE LOSS CHARTS: STEEL, COPPER, PEX
A summary of pressure loss data for piping comes from ASHRAE. The figures below show pressure
(friction) loss for steel pipe, copper pipe, and plastic pipe. PEXa resembles plastic pipe, so the figures are
generally accurate.
Reproduced from ASHRAE. (2009). Pipe Sizing. In Fundamentals (p. 22.7). Atlanta, GA
Hydronic System Design Manual
March 2013
15
PIPING INSTALLATION AND HOOKUP GUIDELINES





DO NOT install polybutylene or PVC plastic pipe.
Provide pipe support according to plumbing code guidelines.
After installation, flush all piping to remove, threading oil, solder flux, and debris.
All check valves and ball valves shall match pipe size. Ball valves shall be full port, if possible.
DO NOT install piping to produce a bull-head tee condition.


Install accessible shut-off valves on the supply and return pipes near the GARN® WHS unit.
Install a separate boiler drain at the designated fitting on the front head of the GARN® WHS
unit.
DO NOT Install automatic air bleeds in a GARN® or any non-pressurized system. Install only
manual air bleeds at all system high points.
In new installations, provide a floor drain (with a hose bib if desired) to accommodate the
overflow pipe and drain valve.
Install a domestic water sill cock for adding water near the GARN® WHS unit. A filter housing
and filter should be mounted in series with, and adjacent to, the sill cock. Use a hose to fill the
unit through the manway opening. DO NOT permanently connect the GARN® unit to a domestic
water source.
Install drain valves in the distribution system where appropriate and required to allow future
maintenance and equipment repair/replacement.
Insulate all above grade piping with ½” wall polyolefin pipe or 1” fiberglass insulation rated to
212°F (Thermocel, Imcolock, Imcoshield are preferred brands).





PLUMBING WITH COPPER:



When installing copper distribution pipe use ONLY: long sweep elbows; 95-5 solder or brazing;
and die-electric couplings where copper pipe joins steel pipe.
DO NOT CONNECT copper pipe directly to the GARN® unit; electrolytic corrosion will occur.
Install 4’ to 6’ of black steel pipe between the GARN® unit and any copper pipe.
PLUMBING WITH STEEL:


Use 2” black steel pipe between the GARN® unit hot water supply connection and the inlet to
the GARN® hot water supply pump.
If installing steel pipe, use ONLY black steel pipe. DO NOT USE galvanized pipe.
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16
CALCULATION OF NET POSITIVE SUCTION HEAD FOR PUMPS
All GARN® wood heating units are zero pressure closed systems as opposed to:


Open system – replaces the vast majority of its contained water daily. A good example of this is
a domestic water heater.
Pressurized closed system – replaces little if any of its contained water on a yearly basis and
operates with an internal pressure of 15 to 30 PSIG. A good example is a standard hot water
boiler that is used for space heating.
A zero pressure closed system does not develop internal pressure due to its unique open vent system.
Such systems do replace a minor volume of contained water on a yearly basis. The designer must
consider net positive suction head (NPSH) when selecting pumps for such systems. Proper selection will
prevent cavitation and suction boiling that can: destroy the pump; prevent the system from attaining its
rated heating capacity; or air lock the hydronic system totally.
Graphs of pump performance and net positive suction head requirements are available from pump
manufacturers. In all cases, the NPSHA available must be greater than the required NPSH for a specific
pump. Generally, lower RPM pumps have lower NPSH requirements.
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17
The net positive suction head available (NPSHA) is calculated:
NPSHA = AP + SP – HL - VP
AP = Job site atmospheric pressure, in feet of water
SP = Static water pressure at the pump, in feet of water
HL = Head loss between GARN® and pump inlet, in feet of water
VP = Vapor pressure at desired HWS temperature, in feet of water
A simple equation for calculating the head loss between the GARN® and the inlet of the pump:
L = Length of pipe between the GARN® and the pump inlet
EL = # of 45° and 90° elbows between the GARN® and the pump inlet
BV = # of ball valves between the GARN® and the pump inlet
GV = # of gate valves between the GARN® and the pump inlet
T = # of tees between the GARN® and the pump inlet
HL, is the summation of pipe, fitting, and valve pressure losses between the GARN® unit and the inlet of
the pump. All losses are to be calculated at maximum system design flow (GPM).
NPSHA must always be greater than the net positive suction head required (NPSHR) for the pump at
design GPM, or cavitation and suction boiling will occur. The NPSHR is provided by the pump
manufacturer (see the Pump Selection and Installation Guidelines section of this manual)
The following tables list atmospheric pressure (AP) at various elevations and vapor pressure (VP) at
various HWS temperatures.
ATMOSPHERIC PRESSURE (AP)
Elevation
(ft)
Sea Level, 0
1000
2000
3000
4000
5000
6000
7000
Atmospheric
Pressure (ft)
33.9
32.8
31.5
30.4
29.2
28.2
27.2
26.2
Hydronic System Design Manual 325666666666666
March 2013
Boiling
Point of
Water (°F)
212
210
208
206
204
202
200
198
18
VAPOR PRESSURE (VP)
System Type
Radiant Floor
Radiant Floor
Radiant Floor
Radiant Floor
Air Coil
European Wall Radiator
Hot Water Baseboard*
HWS Temperature
(°F)
90
104
113
125
125
140
150
Vapor Pressure
(ft)
1.68
2.47
3.5
4.56
4.56
6.65
9.02
* Hot water baseboard can be sized to utilize 140°F HWS
UNDERGROUND PIPING:
Use only oxygen barriered, cross linked, high density polyethylene for underground installation. Preinsulated PEX pipe manufactured by ComfortPro or Uponor is strongly recommended. Underground
piping must be designed to allow for expansion and installed in strict compliance with the
manufacturer’s specific instructions (such as the Microflex installation guide)
http://www.comfortprosystems.com/pdf/MFInstallGuide2009rev1web.pdf







DO NOT install copper, steel, polybutylene or PVC pipe underground.
DO NOT join pipe underground unless absolutely necessary. If required use ONLY materials
provided by the pipe manufacturer and installed according to their specific directions.
In very cold climates place a sheet of 2” thick x 24” to 48" wide foam insulation (blue, pink,
yellow or green) board immediately above the pipe, centered on the pipe before back filling the
trench. Trench depth in cold climates should be 4 feet (grade to top of pipe) if possible.
Deeper burial and additional insulation is required when below grade piping extends beneath a
parking lot or roadway (frost will normally penetrate the soil to a greater depth in such areas).
Pressure test for water leaks before back filling the trench.
If the piping can only be positioned above frost depth, provide a pump timer to circulate water
for five to ten minutes every hour during the heating season.
Avoid burial in continuously wet soils, under creeks, natural land depressions, drainage ponds,
etc.
DRY AREA BURIED PIPING DIAGRAM:


The following diagram shows how preinsulated, underground PEX-a piping shall be laid in dry
areas.
Trench with a “ditch witch” to a depth below the frost line.
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MOIST AREA BURIED PIPING DIAGRAM:

The following diagram shows how preinsulated, underground PEX-a piping shall be laid in areas
where moisture may sometimes be present.
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ROADWAY AND PARKING LOT BURIED PIPING DIAGRAM:

The following diagram shows how preinsulated, underground PEX-a piping shall be laid in areas
where snow is routinely cleared (such as below and paved surface where there is vehicle or foot
traffic).
PUMP SELECTION AND INSTALLATION GUIDELINES:
All pumps must be selected based on a calculated total static and frictional head loss of the piping
connected to the pump as well as the calculated required system flow.
 Preferred pump brands include: Taco, Bell & Gossett, Wilo and Grundfos.
 Select a pump that delivers a flow rate that does not violate the Piping Design and Calculation
Guidelines (see previous section) for head loss and fluid velocity. Size the pump based on a
calculated system head loss and system flow requirement – DO NOT guess.
 All pumps shall be installed in strict compliance with manufacturer’s instructions, with particular
attention to shaft orientation and the length of straight run of inlet and discharge pipe required
to produce stated performance. In most cases, install pumps to discharge vertically up or
horizontally.
 Provide isolation full port ball valves flanges on the inlet and discharge of the pump.
 Pumps should be located adjacent to the GARN® WHS unit if at all possible. Mount pumps at
least 4’ below the surface of the GARN® WHS water level in order to prevent suction boiling at
the pump inlet at higher water temperatures. (See previous section - Calculation of Net Positive
Suction Head For Pumps)
 A heating system may use several zones within a building. Likewise, one GARN® WHS unit may
supply heat to several buildings. Use individual pumps with check values for each zone (or
Hydronic System Design Manual
March 2013
21


building) and develop a common supply manifold to feed the pumps. Likewise, provide a
common return manifold. DO NOT install manifold piping to produce a bull-headed tee
condition.
In a remote location, zone pumps may be mounted adjacent to the heating system PROVIDED:
the total head loss (static and frictional) of the supply pipe is equal to or less than 3 feet; and the
pump is mounted at least 6’ below the surface of the GARN® WHS water level. Again, this is
necessary to prevent suction boiling at the pump inlet. (See previous section - Calculation of Net
Positive Suction Head For Pumps).
DO NOT select a pump to operate near the top of its pump curve as “cycling flow” may occur
with resultant damage to the pump and substandard system heating performance. See the
figure below.
Area of good
selection



In an existing system, the pump size must be confirmed as adequate for the modified system.
Under-sizing a pump will significantly reduce the performance of the heating system and may
allow system piping to freeze.
When hooking into an existing system, use a primary-secondary setup.
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E. SYSTEM DISTRIBUTION CONNECTION AND SCHEMATICS
Refer to the drawings on the next few pages for general schematics associated with a GARN® WHS unit
heating a single building containing either a single zone system or a multiple zone system.
The following drawings are schematics; as such it is neither detailed nor sufficiently complete for
construction. Therefore, a comprehensive design must be completed by either an Engineer or
Mechanical contractor who is knowledgeable about GARN® zero pressure heating equipment and the
particular site conditions for which the schematic is proposed. This schematic is NOT a document of
sufficient detail to yield a functioning heating system.
ZERO PRESSURE, FIXED TEMP - PRIMARY ONLY PUMPING:
A zero pressure, fixed temp system delivers a fixed water supply temperature to a non-pressurized
hydronic heating system. Such a system is “zero-pressure” because the heating system is in direct
contact with the atmosphere at the GARN unit. As the system heats up, the expansion of the water is
reflected in the level of the GARN unit.
Advantages
Disadvantages
 Simple.
 Cannot connect to a pressurized system.
 No expansion tank required.
 If pumping to a level higher than the level
of the GARN unit, the system will drain
 Constant speed or variable speed pump
back to the GARN which could prevent
can be used.
many pipes from remaining “wetted”.
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ZERO PRESSURE, FIXED SUPPLY TEMP – PRIMARY SECONDARY
PUMPING:
A primary-secondary pumping scenario involves two pumps: The primary pump circulates water
between the GARN unit and the heat distribution piping; the secondary pump circulates water through
the heat distribution piping.
Advantages
Disadvantages
 The main advantage of this type of system
 Cannot connect to a pressurized system.
is that it can be directly connected to an
 If pumping to a level higher than the level
existing zero pressure heating system.
of the GARN unit, the system will drain
 Temperature and flow can be controlled
back to the GARN which could prevent
independently.
many pipes from remaining “wetted”.
 Primary loop pump only needs to be sized
from the primary loop piping.
 Secondary loop pump only needs to be
sized for secondary loop piping.
 No mixing valve required.
 No expansion tank required.
Hydronic System Design Manual
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ZERO PRESSURE, MULTIPLE ZONE – PRIMARY SECONDARY PUMPING:
Another pump/piping strategy that can allow for a better control, smaller pumps and fewer design
calculations is a “primary secondary pumping system” (refer to the drawing on the following page). This
drawing details a single GARN® unit providing heat to two separate buildings, a home and a shop. Note
the following:

Pumps P1 and P3 circulate water from the GARN® WHS unit to a pair of closely spaced tees
within each building and then back to the GARN® WHS unit. The two pumps are sized based
upon the head loss of the underground piping and the manifolds at the GARN® WHS unit. The
head loss for the piping within either building is NOT taken into account. This makes for simpler
piping head loss calculations when interfacing with an existing system.
The underground piping and the GARN® manifold are considered the “primary piping loop.”

Pumps P2 and P4 simply circulate warm water (a mixture of cool system return water and hot
supply water) to the heat delivery system in the building. The two pumps are sized based upon
the piping and equipment head losses within the building without taking into account the head
loss of the underground piping or the manifold at the GARN® WHS unit. This allows a good
match between pumps P2 and P4 and the heat delivery equipment (air coil, hot water
baseboard, radiant floor, or any combination thereof). In fact multiple small pumps may be used
to split the building into independently controlled heating zones. Again, this makes for simpler
piping head loss calculations when interfacing with an existing system because the existing
pump generally does not have to be replaced as it experiences no net change in its resistance to
flow.
The piping in the building is considered the “secondary piping loop.”
One could further increase the energy efficiency of this system by using variable speed pumps for P1
and P3. The speed of the pumps would be controlled by an optional temperature sensor or even an
indoor-outdoor reset temperature controller. In this case, with the GARN® WHS unit hot (say 195°F) P1
and P2 would run slowly as only a small volume of hot GARN® WHS water would be required to warm
the water within the secondary piping loop. When the GARN® WHS unit was cool (say 125°F) the pumps
would provide a greater flow to warm the water within the secondary piping loop.
Some specifics about the closely spaced tees:





The tees should be no more than 6 pipe diameters apart.
The tees should be located on the return side of any existing hot water heating system.
Flow between the tees may reverse direction when the secondary system pumps (P2 and P4)
are activated.
The piping reducers are beyond the 12” of pipe and the two tees.
Activation of P1 and P3 may be interlocked with P2 and P4 except when there is a possibility of
the underground piping freezing.
Hydronic System Design Manual
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Hydronic System Design Manual
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26
CONNECTING TO AN EXISTING PRESSURIZED OR GLYCOL TREATED
DISTRIBUTION SYSTEM:
DO NOT connect your GARN® unit to an old, dirty or glycol treated hydronic
system until the system has be thoroughly cleaned and flushed.
Conventional hydronic distribution systems with a steel or cast iron boiler, cast iron radiators, copper
hot water baseboard, or water to air coils, may contain a sludge or solution that can attack the steel in
your GARN® heat storage system. Over time bacteria, debris and/or glycol can transform into this very
corrosive sludge/solution. This liquid SHOULD NOT BE MIXED with the GARN® storage water. Rather the
existing system MUST be completely drained and flushed with a chemical cleaner before connecting it
to the GARN® unit. Contact PrecisionChem for proper chemical and procedures:
Mike Kuzulka @ PrecisionChem Water Treatment
W7231 State Road 49
Waupun, WI, 53963
1-(920)-324-2007 (call with any questions)
Anti-freeze used in distribution systems must be replaced after 3 - 5 years.
Anti-freeze slowly degrades over a period of time and transforms into a very
aggressive solution that readily attacks steel. Any hydronic system that uses antifreeze MUST be
periodically checked and the antifreeze replaced before it becomes aggressive.
Isolate the GARN® water from the distribution system with a heat exchanger. If
the distribution system requires anti-freeze, the distribution system MUST be
isolated from the GARN® WHS heat storage water with a flat plate or equal heat exchanger.
The design and installation of your distribution system may cause the GARN® tank
to become sacrificial, if proper procedures are not followed. Connect only black
steel pipe to GARN® unit, install dielectric couplings where copper pipe connects to steel pipe, install the
chemicals provided and test/maintain your water chemistry twice per year. Sacrificial anode rods further
help reduce the potential for this type of corrosion.
Carefully follow all procedures specified in the GARN® WHS Owner’s Manual.
Hydronic System Design Manual
March 2013
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PRESSURIZED, FIXED SUPPLY TEMP – CONSTANT SPEED PUMPING
The following piping configuration provides a fixed supply temperature via an adjustable mixing valve
and brazed-plate heat exchanger. A heat exchanger separates the system’s primary (GARN side) from
the secondary (heat distribution) side. The primary pump circulates water between the GARN unit and
the heat exchanger; the secondary pump circulates water around the heat distribution piping. When
the space calls for heat, controls activate both pumps.
Advantages
Disadvantages
 Can be easily connected to a pressurized
 The heat exchanger must be sized and
system.
piped properly. Notice the “counter flow”
configuration on the heat exchanger. See
 Simple and robust, uses constant speed
discussion in in the Water to Water Flat
pumps.
Plate Heat Exchanger section of this
 The heat exchanger separates the GARN
manual.
from the heat distribution system, so
 The strainers must be maintained and
glycol can be used.
cleaned so the heat exchanger does not
plug up and lose performance.
 If the primary pump is improperly sized it
can circulate more water than necessary
through the GARN unit and the system
won’t be able to take advantage of
thermal stratification.
Hydronic System Design Manual
March 2013
28
PRESSURIZED, FIXED SUPPLY TEMP – VARIABLE SPEED PUMPING
The following piping configuration provides a fixed supply temperature via a variable speed primary
pump and constant speed secondary pump. A heat exchanger separates the system’s primary (GARN
side) from the secondary (heat distribution) side. The primary pump circulates water between the GARN
unit and the heat exchanger; the secondary pump circulates water around the heat distribution piping.
When the space calls for heat, controls activate both pumps.
Advantages
Disadvantages
 Can be easily connected to a pressurized
 The heat exchanger must be sized and
system.
piped properly. Notice the “counter flow”
configuration on the heat exchanger. See
 No mixing valve required.
discussion in in the Water to Water Flat
 A variable speed pump will only supply as
Plate Heat Exchanger section of this
much water as necessary to maintain a set
manual.
HWS temperature on the secondary side
 The strainers must be maintained and
of the heat exchanger. This allows the
cleaned so the heat exchanger does not
system to take full advantage of the GARN
plug up and lose performance.
tank’s thermal stratification.
 The heat exchanger separates the GARN
from the heat distribution system, so
glycol can be used.
Hydronic System Design Manual
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F. SYSTEM COMPONENT CONNECTION AND SCHEMATICS
CONNECTION TO FORCED AIR FURNACE:
FORCED AIR GUIDELINES:
A water/air coil may be added to some forced air furnaces or blower cabinets to serve as the primary
source of heat. When the room thermostat demands heat, water from the GARN® unit is circulated
through the coil and the blower moves air through the coil. In a dual-fuel installation, the thermostat
will activate the auxiliary heating unit if there is insufficient heat from the GARN® storage tank.
When adding a water/air coil to any forced air furnace:



DO NOT relocate, modify or rest any of the safety controls in the original furnace installation.
Blower pulleys and motor pulleys may be changed, but the electrical current flowing through
the motor is to be maintained within the nameplate rating. Under some circumstances a larger
motor may have to be installed.
Any water/air coil added to the system must be installed in accordance with the instructions of
the manufacturer and in a manner acceptable to the regulatory authority by mechanics
experienced in such services.
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30
COIL SELECTION
Check the nameplate on existing heating system for BTU/HR output, blower CFM and allowable external
static pressure. Measure the external static pressure with a clean filter in position.





Choose coil based on desired BTU/HR output and LOWEST entering water temperature (usually
125°F to 130°F EWT).
Choose circulating pump based on required water flow and total system pressure drop,
Determine if EXISTING furnace blower is adequate. If NOT adequate, and furnace is in GOOD
condition, replace blower assembly or blower motor and pulleys to yield proper flows. If NOT
adequate and furnace is in POOR condition, replace the furnace with a new furnace of proper
blower capacity. Or replace the furnace with a package fan-coil unit. If the furnace is adequate
and in good condition, install the coil.
DO NOT install a coil in a system that utilizes a high efficiency or condensing furnace.
Call your local GARN® dealer for coil selection and pricing.
HIGH LIMIT SWITCH (DUCT STAT)
If the HWS temperature to the coil is greater than 140°F an optional high limit switch (sometimes called
a duct stat), must be installed on the downstream side of the coil. The duct stat provides overheating
protection for the space being heated. If the temperature of air discharged from the coil exceeds 140°F,
the switch stops the fluid flow through the coil.
BLOWER SPEED AND CFM ADJUSTMENT
It is very important that the proper air volume is supplied to the heated space, across the furnace’s heat
exchanger, and across the coil. These air volumes are to be determined by design specifications. A draft
gauge reading of pressure drop across the furnace is taken before the coil is installed. This yields the
initial system air volume. After the coil is installed, a pressure drop across the coil should be taken to
indicate the new system air volume. This new system air volume must be adjusted to supply:
1. The minimum air volume across the furnace’s heat exchanger as specified in the manufacturer’s
engineering data.
2. The proper air volume across the coil to yield the required output
3. The proper air volume to heat the space.


A minimum of three 1/4” air test holes must be drilled. One in the ductwork on both sides of the
furnace and one on both sides of the coil. Refer to following diagram.
Connect draft gauge across the blower. The zero end of the draft gauge scale connects to the air
entering side. Insert the hoses so about 1/4’ extends inside the plenum. Seal around holes.
Hydronic System Design Manual
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31




Start furnace blower motor by placing the thermostat fan switch in continuous position with no
heating or cooling demand. Turn on power.
Refer to the manufacturer’s literature for the list of air volumes and equivalent draft gauge
readings. Observe draft gauge reading, if reading is below required air volume, increase blower
speed. If reading is above required air volume, decrease blower speed. Refer to furnace wiring
diagram for changing direct drive blower speed.
On belt drive blowers, check amperage draw on motor by connecting an ammeter to one leg of
the motor supply line and comparing this reading with the full load amps listed on the motor
nameplate. The motor pulley must be adjusted not to exceed the motor nameplate full load
amps for motor installed.
After required draft gauge readings are obtained, remove draft lines and insert snap hole plugs
in air test holes.
CONNECTION TO HOT WATER BASEBOARD SYSTEM:
HOT WATER BASEBOARD GUIDELINES
Install good quality (even commercial grade) hot water baseboard. Sterling® is a preferred brand
(http://www.sterlingheat.com/). Cheaper grades produce fewer BTU’S per linear foot of baseboard.
Look for copper tube/aluminum finned elements, full back plates and die formed hangers with nylon or
roller slides to eliminate noise. In addition:

Size the baseboard for 140°F supply water temperature and a 20°F temperature drop.

Circuit baseboards in a parallel configuration so that all elements receive the same 140°F supply
water.

Use copper or oxygen barriered PEX for supply and return piping.
Hydronic System Design Manual
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32

Size the pump to provide 1 to 1.5 gpm of flow at a maximum velocity of 4 FPS through each
baseboard.

Individual room-by-room control is best. This is easily accomplished by using a radiant floor
manifold with individual runouts to each HWBB section. If this is not possible, try to zone the
system so that rooms with similar heat loss characteristics are on the same circuit.

Whenever a zone thermostat calls for heat, the pump serving that zone is to be activated.

Strictly follow the manufacturer’s installation and placement instructions.
NEW CONSTRUCTION
Determine the linear footage of wall that is available for the placement of the hot water baseboard.
Divide the BTUH heat loss of the building by the available footage. Select the baseboard units that can
supply the BTU’s per foot required to meet the building’s heat loss. Select the baseboard based on a
supply water temperature of 140°F. If the available linear wall footage is not sufficient, adding more
baseboard, selecting a more efficient baseboard, or selecting a larger GARN® unit with greater thermal
storage is required.
CONVERTING AN EXISTING BASEBOARD SYSTEM
Most installers select a GARN® system that will supply 140°F water to a baseboard system. If the existing
system was supplying water at a higher temperature, say 180°F, an analysis must be done to determine
whether a lower supply water temperature will meet the needs of the building. The following table can
be used for this purpose.
Water Temperature Correction Factors (entering air temperature = 65°F)
Supply Water Temperature (°F)
Correction Factor
100 110 120 130 140 150 160 170 180 190 200 210 215
0.13 0.19 0.25 0.31 0.38 0.45 0.53 0.61 0.69 0.78 0.86 0.95 1.00
The above table can be used to determine the difference between the BTU/HR delivered by the existing
system vs. the BTU/HR that can be delivered by the GARN® system at a lower supply water temperature.
A standard of 215°F is used in the industry as the basis for rating. If a baseboard is rated at 1000
BTU’s/linear foot at 215°F (contact manufacturer for output ratings), the table indicates that at 180° the
existing baseboard can deliver 69% of the rated BTU’s or 690 BTU’s/linear ft. A GARN® system sized to
use 140° water will yield 38% of the rated BTU’s or 380 BTU’s/linear ft. If the old system was sized twice
as large as the actual heat loss (a common occurrence), then the sizing of the GARN® system for 140°
water is correct. If more heat is required, a larger storage system or more baseboard footage will be
required.
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The drawing below shows a simple, single zone hot water baseboard system.
CONNECTION TO HYDRONIC RADIANT FLOOR SYSTEM:
RADIANT FLOOR GUIDELINES:
Use only oxygen barriered, cross-linked, high-density polyethylene for radiant floor installation.
ComfortPro, Uponor, and Roth are the preferred brands. Radiant floor systems must be installed in strict
compliance with the manufacturer’s instructions. In addition:

DO NOT USE steel, copper, rubber based hose (such as Heatway or Entran tubing), low-density
polyethylene, polybutylene or PVC plastic pipe as radiant floor tubing. All of these involve
significant and complex corrosion and durability issues for the tubing, pumps, controls, and
GARN® equipment.

The installation of rubber based hose (such as Heatway or Entran tubing), low-density
polyethylene, polybutylene or PVC plastic pipe in a radiant floor system directly connected to a
GARN® unit will void the GARN® and pump warranty.

In new construction, install 2” of blue, yellow, green or pink foam board (extruded polystyrene
foam – minimum of 1.6 PCF density, per ASTM C 578-95 specification) under the entire slab that
is to be radiantly heated. The foam should be placed immediately below the bottom of the slab,
on 6” of well compacted granular fill. This construction provides a proper structural bed
(compacted gravel) and minimizes downward heat loss.

When radiant heating is installed on above grade floors, the underside of the floor MUST be
insulated to prevent downward heat loss and overheating of the rooms below. A minimum
insulation valve of R =13 is recommended.

The radiant floor manifolds supplied by the manufacturers listed, provide for room-by-room
control while using only a single pump and mixing valve.
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
Install a 3 way mixing valve to blend cooler radiant floor return water with hot supply water
from the GARN® unit in order to maintain the moderate supply water temperatures (between
95°F and 130°F) required for radiant floor heating. Mixing valve brands are Paxton ESBE,
Honeywell Sparco and Watts. Install mixing valve between the GARN® unit and pump so that the
pump draws through the valve from the GARN®.
CONNECTION TO AN EXISTING PRESSURIZED SYSTEM
Retrofitting a GARN® WHS unit to an existing pressurized heating system requires the installation of a
pressure rated flat plate heat exchanger. Contact your local GARN® dealer or DECTRA CORPORATION for
sizing, availability and pricing of FlatPlate heat exchangers. Note the following and review the drawing:






DO NOT connect any GARN® unit to a steam boiler or steam heating system.
The water-to-water heat exchanger must have a pressure rating that is equal to or greater than
the pressure rating of the existing boiler. Consider changing the system to a primary secondary
system.
Position the heat exchanger on the return side of the existing boiler.
The GARN® unit and the heat exchanger shall NOT be installed so as to interfere with the normal
delivery of heated water from the existing boiler.
The GARN® unit and the heat exchanger shall be installed without changing the function of the
controls or rewiring the existing boiler. A control wiring connection is permitted only if required
to obtain proper operation. For instance, when a thermostat calls for heat, both the GARN®
pump and the existing pump are to be powered.
The electrical system of the existing boiler and GARN® pumps must be powered from a single
branch circuit, without exception.
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The following table is used to determine an initial heat exchanger size. A final selection should be made
with the manufacturer’s computer selection software. DECTRA CORPORATION can provide this service.
WATER TO WATER FLAT PLATE HEAT EXCHANGERS
MODEL
BTUH
OUTPUT
REQ'D
GPM
FITTING
SIZE
PRESSURE
DROP, FEET
STRAINER
SIZE
MIN
PIPE SIZE
5 X 12 - 16
5 X 12 - 24
5 X 12 - 30
5 X 12 - 36
5 X 12 - 50
5 X 12 - 50
10 X 20 - 30
25,000
50,000
75,000
100,000
125,000
150,000
200,000
3
5
7.5
10
12.5
15
20
3/4"
1"
1"
1 1/4"
1 1/4"
1 1/4"
1 1/2"
3'
3'
3'
4.5'
3.5'
4'
6'
3/4"
1"
1"
1 1/4"
1 1/4"
1 1/4"
1 1/2"
3/4"
1"
1 1/4"
1 1/4"
1 1/4"
1 1/4"
1 1/2"

BTUH output listed is based on a 10°F approach temperature (see diagram for explanation):



All unites are pipe counter flow according to their manufacturer’s rules.
BTUH output listed assumes no glycol.
Larger heat exchanger sizes and units for use with glycol based systems are available. Contact
the DECTRA CORPORATION for specific sizing.
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
The pipe size indicated is the minimum pipe size based on 4’ of head loss per 100’ of pipe.
CONNECTION TO AN ELEVATED SYSTEM
Even though the GARN® WHS unit is non-pressurized, it is adaptable to heating systems that are
elevated up to 16’ above the level of the slab on which the GARN® unit sets. If the vertical distance is
greater than this, a flat plate water-to-water heat exchanger must be installed (refer to “Connection to
an Existing Pressure System). Note the following and review the drawing:






This type of system is found mostly in warehouses with high ceilings and in multiple floor
residences or small commercial facilities.
All piping and flanges MUST be airtight or this type of installation will not function properly. Air
leaks will constantly bleed air into the system (negatively affecting both system performance
and corrosion).
DO NOT use automatic air bleeds in the heat delivery system. Install only manual air bleeds.
Select pump to overcome total head, i.e., pipe friction and vertical elevation. Pump sizing is very
critical in this application.
Install a solenoid valve that is energized to open when the pump is powered. This valve is to
close whenever the pump is not powered. The valve locks the water in vertical loop when the
pump is not operating.
Install a reliable full-port, spring check valve downstream of the pump.
CONNECTION TO DOMESTIC HOT WATER
Heating of domestic water is easily accomplished with GARN® equipment. In-tank copper water heating
coils are NOT provided in the GARN® tank for several reasons:
Hydronic System Design Manual
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
A copper coil in any steel boiler creates electrolytic corrosion, leading to early tank failure.

With a coil inside a remote boiler, two additional below grade insulated domestic water lines are
required (a supply and return line that connects the coil to the water heater). This adds
significant cost to the project.
Any domestic hot water heating system must comply with the following rules:

All domestic water piping, valves, fittings, pumps, controls and the overall installation must
meet all national and state plumbing, sanitation and health codes.

After installation is complete, the entire domestic waterside of the system must be pressure
tested, flushed, and then sanitized according to local health department requirements.

In all cases, a NSF or Board Certified anti-scald mixing valve is required by national and state
codes when preheating or heating domestic water with equipment other than a conventional
water heater. The valve shall be set to deliver hot water at a temperature of 120°F maximum.
The two methods of preheating domestic water include:
1. An external “saddle mounted” or “side-arm” heat exchanger. A double walled, leak detecting
tube within a tube all copper water-to-water heat exchanger is the recommended “saddle type”
heat exchanger. This heat exchanger is to be mounted, close to and slightly below the level of
the top of the existing water heater. Saddle heat exchangers can be installed to thermo-siphon
or use a pump on the domestic waterside.

Install a differential thermostat to control the small (1/25 hp) system pump. The domestic water
within the water heater should be heated to 145°F in order to kill water borne Legionelle
bacteria. The “hot sensor” of the control should measure the GARN® water temperature; the
“cold sensor” should measure the domestic water temperature at the inlet of the heat
exchanger. The sensors may be “strapped” to the pipe and covered with insulation in order to
provide accurate temperature readings to the differential controller.
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2. A stand alone “indirect fired” tank heat exchanger. Indirect fired tank heat exchangers
generally include a stainless steel internal coil within an insulated stainless steel tank. This unit is
then connected in series upstream of the existing water heater. Contact your GARN® dealer for
sizing, availability and pricing of a preheat unit. The following applies to any domestic water
heating system:
For more information on indirect fired water tanks visit:
http://www.triangletube.com/
http://www.weil-mclain.com/
http://www.heat-flo.com/
SOLAR INTERFACE:
GARN® equipment can be ordered factory ready to connect to solar collectors. The collector with the
simplest interface is the drain-back solar collector. Water is pumped from the GARN® unit to the
collector, is circulated through the collector, and then drained back into GARN® unit via gravity. The
optional ¾” FPT flanged fitting on the left side of the manway collar is the drain back fitting where the
return line from the collectors is to be connected.
Some solar collector designs utilize a collector non-water based medium in lieu of water. Such collectors
require a heat exchanger to interface with the GARN® unit.
Refer to manuals and data provided with the solar collectors regarding proper installation.
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G. BACKUP HEATING WITH THE EXISTING SYSTEM OR
ELECTRIC
If the GARN® unit is being added to an existing building, the existing heating system will normally be
used as a backup system. Off peak electric heating is available as part of the GARN® unit to serve as a
backup to the wood heating. Some utility companies offer discounted electric rates to installations using
electric heat with heat storage equipment. Contact your local utility about various programs. Then
contact your GARN® dealer for electric backup heating options.
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H. EXAMPLE PROBLEM – HOUSE WITH REMOTE POLE
BARN/WORKSHOP
The following example problem uses the tools in this manual to size piping, pumps, and GARN® heating
equipment for a typical house with a pole barn/workshop.
EXAMPLE PROBLEM SETUP:
House:
 Main floor – 1100 sq. ft - hot water base board (HWBB)
 Basement – 1100 sq. ft – radiant floor
 Newer construction – built in 2007
Shop:








Pole barn (where GARN® unit is to be located)
30’ x 40’ = 1200 sq. ft
Radiant floor
R19 walls, R38 ceiling, R10 underslab insulation
1 – 8’x10’ overhead door
1 – Personnel door
3 – 3’x4’ windows
Located 127’ from house
HOUSE DESIGN:

Estimate heat load (see “Rules of Thumb for an Initial Estimate of Equipment Size”)
[
]
[
]
MAIN FLOOR DESIGN:





HWS = Choose 145°F
ΔT = 10°F
HWR = 135°F
HWBB – rated at 980 btuh/ft at 215°F
HWBB correction factor = 0.38 (see “Water Temperature Correction Factors”)
[
[

Total feet of active fin tube =
[
]
]
]
The total feet of active fin tube needs to be divided up among the main floor rooms based on a
calculated heat loss for each room. The fin tube can be roughly split:
Hydronic System Design Manual
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ROOM
AREA (sq. ft) FIN TUBE LENGTH (ft)
Eat in Kitchen
204
10’
1-1/2 Baths
100 (total)
5’
3 Bedrooms
156 (each)
8’ per room
Living Room
280
14’
Hall
48
0’ (no load – internal)
Total
53’
Main Floor Flow Calculations
However, the minimum flow through any run of HWBB is typically = 1 gpm, with NO more than 20’ of
HWBB in any single run. Therefore:
Kitchen: 10’ < 20’ = 1 gpm
1-1/2 Bathrooms: 5’ < 20’ = 1 gpm
Living Room: 14’ < 20’ = 1 gpm
Bedrooms: 8’ each < 20’ = 1 gpm per bedroom (3 gpm total)
6 gpm total required
A radiant floor manifold can be used with HWBB or wall mounted panel radiators to provide for
individually controlled zones. In this case each bedroom could be a single zone with the remainder of
the main level a single zone for a total of 4 zones. See the following diagram:
Figure 1: Main Level Floor Manifold Schematic
Use wall-mounted thermostats with manifold mounted zone control valves with end switch.
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BASEMENT LEVEL DESIGN:


Assume no carpet
1 zone radiant floor
From radiant floor manufacturer’s data:
 Install radiant loops 12” on center
 The manufacturer chosen for this example recommends a maximum loop run of 300’ for ½” PEX.
The maximum loop length varies from manufacturer to manufacturer and by pipe size. See
“Radiant Floor Heating” section of this manual.
 Average loop temperature required is 85°F
 HWS = 90°F (for a bare, concrete floor)
 ΔT = 10°F
Calculate the # of loops of ½” PEX:
[
]
Basement Flow Calculations:
]
[
SIZE THE MAIN FLOOR HOUSE PUMP
Each HWBB section includes a 3/4” copper fin tube element. At 1 gpm, head loss for 3/4” copper is
about 0.5’ per 100’ (see, “Flow and Heat Capacity Tables”). The head loss for 1/2” PEX at 1 gpm is
approximately 3’ per 100’.
HWBB Loss
(
(
1/2” PEX
Radiant Manifold
1” Copper Feed to Manifold
)
)
2’
(
)
1” Mixing Valve
4’
Subtotal
8.31’
Misc Fittings
10%
Total Head Loss
9.14’
Size the house pump for 6 gpm @ 9.14’
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Choose a Taco 007-IFC variable speed pump with pump control center and room thermostat. For more
information see:
TACO® HVAC 007-IFC Circulator
TACO® 007-IFC Performance Curve
SIZE THE BASEMENT PUMP
275’ of ½” PEX @ 0.75 gpm
(
Radiant Manifold
1” Mixing Valve
)
2’
4’
(
¾” Copper Feed 20’
)
Subtotal
12.9’
Misc Fittings
10%
Total Head Loss
14.2’
Size the house pump for 3 gpm @ 14.2’
Choose a Taco 0015 3-speed pump with pump control center and room thermostat. Set pump to speed
2. For more information see:
TACO® HVAC 0015 Circulator
TACO® 0015 Performance Curve
DISTRIBUTION PIPE AND PUMP SIZING
Total Flow = 6 (main floor) + 3 (basement) = 9 gpm
The owner desires to locate the GARN® unit in a pole barn shop. The shop is 127’ from the house. What
size MicroFlex® PEX is required? Compare 4’ per 100’ of head loss to 6’ per 100’ for the distribution
piping:
4’ per 100’ use 1-1/4” MicroFlex® Duo PEX
6’ per 100’ use 1” MicroFlex® Duo PEX
Assume the MicroFlex® is buried below the 4 ft. frost line in Minnesota. Therefore, about 6’ must be
added to the GARN® end and 2’ to the house end where the pipe enters the basement.

1-1/4” Head Loss =
(
)
Cost = 28 cents/ft
1” Head Loss =
(
)
Cost = 19 cents/ft
Choose the 1” MicroFlex to save money on the initial install.
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SIZE DISTRIBUTION PUMP
MicroFlex®
16.2’
1-1/4” Copper @ GARN®
(
)
2” Steel @ GARN®
(
)
Mixing Valve
4.75’
Subtotal
22’
Misc Fittings
10%
Total Head Loss
24.2’
Size the house pump for 9 gpm @ 24.2’
Choose a Taco 0011-IFC variable speed pump with pump control center. Activate pump whenever
house pump activates and set to maintain ΔT=10°F. For more information see:
TACO® HVAC 0011-IFC Circulator
TACO® 0011-IFC Performance Curve
POLE BARN DESIGN
Estimate the heat loss (using ASHRAE methods):
(
(
) (
)
)
[
]
Total Heat Loss = 18,155 [btuh]
Notice that the overhead door, personnel door, and windows are 39.5% of the total loss.
From a Radiant Floor Design manual for 5/8” tubing at 12” on center:
 Surface temperature = 76°F
 EWT = 85°F; RWT = 75°F; Avg. water temperature = 80°F
 Assume no glycol
Maximum length for 5/8” PEX tubing = 450’. Calculate # of loops for 5/8” PEX:
Hydronic System Design Manual
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[
]
]
[
See the following diagram:
Figure 2: Pole Barn Schematic
SIZE POLE BARN PUMP
400’ of 5/8” PEX @ 1.20 gpm
(
Manifold
2’
(
20’ of ¾” Type L Copper
Mixing Valve
12’ of 2” Steel Pipe @ 12.5 gpm
)
)
3.6’
(
)
Subtotal
14’
Misc Fittings
10%
Total Head Loss
15.4’
Size the house pump for 3.4 gpm @ 15.4’
Choose a Taco 0015 3-speed pump with pump control center and room thermostat. Set pump to speed
2. For more information see:
Hydronic System Design Manual
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TACO® HVAC 0015 Circulator
TACO® 0015 Performance Curve
Because the pole barn piping is 85°F water, there is no need to check the Net Positive Suction Head.
Reference the following figure for the GARN® side system schematic:
Figure 3: GARN® System Schematic
Refer to earlier sections of this design guide for suggested locations of ball valves, dielectric unions, air
vents, etc.
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