Technical Guide_Energy Recovery Wheel

Technical Guide_Energy Recovery Wheel
Desiccant Wheel Products
Energy Recovery Wheel
Technical Guide
Table of Contents
Introduction.............................................................................................1
The Ventilation Mandate........................................................................1
Typical Applications.................................................................................2
Benefits.....................................................................................................2
Design Features .......................................................................................3
Recovering Total Energy..........................................................................6
Recovering Sensible Only........................................................................7
Unit Selection..........................................................................................8
Unit Selection Example.........................................................................11
Purge Section..........................................................................................14
Fan Location Options............................................................................16
Drive Motor Location............................................................................16
Filtration Requirements........................................................................17
Odors and Contaminants......................................................................18
Wheel Speed Control............................................................................19
Preheating to Avoid Frost Formation.............................................20
Controlling Wheel Speed To Avoid Frost Formation...................20
Avoiding Overheating (Economizer Cycle)...................................21
Automatic Summer-Winter Change Over.....................................21
Condensation on Sensible Only Wheels........................................21
Sensible Wheel Performance.................................................................22
Sensible Wheel Applications.................................................................23
Condensation & Frosting......................................................................23
Cleaning The Wheel Media..................................................................24
Installation Guidelines...........................................................................24
Typical Wiring Schematic.....................................................................25
Mounting Arrangements.......................................................................26
Wheel Drive Options.............................................................................26
Ordering Key..........................................................................................27
Performance Data for TE3 and TS Wheels..........................................28
Unit Dimensions....................................................................................28
Sample Specification.............................................................................29
How to Reach SEMCO.........................................................................30
Wheel Configuration Checklist............................................................31
Psychrometric Chart..............................................................................32
© SEMCO Incorporated 1990-2007. All rights reserved.
The information in this technical guide is furnished for informational use only, is subject to change without notice, and
should not be construed as a commitment by SEMCO Incorporated. SEMCO Incorporated assumes no responsibility
for any errors that may appear in this technical guide.
No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means,
electronic, mechanical, recording, or otherwise, without the prior written permission of SEMCO Incorporated.
U.S. patented technology: 5,401,706 ; 5,496,397
EXCLU-SIEVE, SEMCO, and the SEMCO logo are registered trademarks of SEMCO Incorporated.
i • Energy Recovery Wheel Technical Guide
Introduction
This design manual presents the SEMCO EXCLU-SIEVE® total energy (TE3) and sensible only (TS) recovery wheels. It explains features
and benefits provided by this technology, provides a detailed selection
procedure and reviews specific guidelines to assure an effective system
design. This material should be reviewed carefully before beginning the
design process.
Please contact your local SEMCO sales representative for additional design support or to answer any technical questions, which go
beyond the scope of this brochure. You will find a listing of SEMCO
sales representatives on our website. Please point your browser to www.
semcoinc.com. You can reach SEMCO Incorporated on our toll free
line at 888-473-6264.
The Ventilation Mandate
ASHRAE Standard 62, Ventilation for Acceptable Indoor Air Quality,
defines the minimum outdoor air ventilation rates required to achieve
acceptable indoor air quality. This standard, which is referenced in part
or whole by all building codes in the United States, recommends that
outdoor air quantities be increased from 5 cfm per person to 20 cfm
per person (in an office environment) to avoid adverse health effects.
Although most owners, architects and engineers recognize the benefits
of bringing in more outdoor air, many are concerned about the impact
on equipment and operating costs.
EXCLU-SIEVE provides the solution to the ASHRAE 62 mandate.
It pre-cools and dehumidifies the outdoor air during the cooling season
and preheats and humidifies the outdoor air during the heating season.
As a result, the outdoor air quantity can be increased from 5 to 20 cfm
per person without increasing energy costs.
As importantly, the first cost savings associated with the reduction
in chiller and heating/humidification capacity typically pay for the
added cost associated with the installation of the total energy recovery
equipment.
As shown in Figure 1, significant reductions in the heating/cooling
plant capacity can be recognized through the application of total energy
recovery.
Figure 1. Savings potential with
EXCLU-SIEVE® technology when
increasing the ventilation air
amount from 5 cfm/person to 20
cfm/person.
Annual Savings Potential in $000
0
5
10
15
20
25
30
35
Atlanta
Boston
St. Louis
Annual energy savings estimated for continuous operation of a 10,000cfm system
First cost savings estimate due to chiller and boiler capacity reductions for
a 10,000 cfm system; assumes $500/ton chiller first cost and $400/bhp boiler first cost
Energy Recovery Wheel Technical Guide • 1
Typical Applications
Energy recovery equipment can be applied to a wide variety of
applications:
• Schools, universities, dormitories;
• Offices, condominiums, apartments;
• Smoking lounges, casinos;
• Hospitals, nursing homes, day care centers;
• Hotels, motels, department stores;
• Clean rooms, circuit board, chip manufacturing;
• Breweries;
• Swimming pools, sports arenas;
• Convention centers, airports, prisons;
• Bus and train maintenance facilities;
• Welding, foundry, casting areas;
• Printing operations;
• All humidity controlled spaces; and
• Product drying operations.
Benefits
The SEMCO EXCLU-SIEVE technology affords a number of
benefits:
• Independently certified wheel performance.
• Equal latent and sensible heat transfer.
• Highest effectiveness for given size equipment.
• Virtually no cross-contamination (independently certified to be less than 0.04 percent).
• Field adjustable purge section.
• Wheel independently certified to pass NFPA 90A requirements for
flame spread and smoke generation based upon ASTM E84 fire test
method.
• Reliable operation.
• Low maintenance.
• Low operating costs.
• Long life expectancy.
• Can be applied where stationary heat exchangers cannot.
2 • Energy Recovery Wheel Technical Guide
Design Features
Tubular Steel Casing Construction
Extruded Aluminum Hub
Heavy Wall I-Beam Shape
Extruded Aluminum Spoke
Media may be installed or removed
through a standard access door
Heavy Wall Extruded Aluminum Rim
Recovery Effectiveness (in %)
Velocity
(fpm)
EXCLU-SIEVE
Competition
400
86.0
81.0
600
80.5
75.5
800
77.0
70.5
1000
74.5
66.0
Pressure Loss (in in. w.g.)
Velocity
(fpm)
EXCLU-SIEVE
Competition
400
0.37
0.45
600
0.56
0.66
800
0.79
0.89
1000
1.05
1.15
Table 1. Comparison of
SEMCO’s EXCLU-SIEVE wheel
performance with published data
by competitors.
Superior Certified Performance Allows Compact Design
The performance data published for the EXCLU-SIEVE Energy Wheel
is independently certified in accordance with ASHRAE 84-78P and is
far superior to all other air-to-air energy recovery systems.
A unique flute design, coupled with numerous other design
innovations, provides for the highest possible heat transfer characteristics
while simultaneously reducing pressure loss parameters.These combined
features optimize the “sensible” (temperature) recovery portion of the
performance.
Providing “latent” (moisture) recovery efficiencies that match the
improved sensible values is made possible by EXCLU-SIEVE’s 3Å
molecular sieve desiccant coating. The “rate of adsorption” by this
transfer surface is more than twice that of other desiccants. This allows
for effective moisture transfer from the high velocity airstreams inherent
in energy recovery applications.
EXCLU-SIEVE’s performance advantage is best shown by the
comparison chart in Table 1. Notice that EXCLU-SIEVE has a better
performance than the competition for a given face velocity. The higher
effectiveness at a lower pressure drop maximizes savings.
Energy Recovery Wheel Technical Guide • 3
3Å Molecular Sieve Desiccant Coating
The EXCLU-SIEVE wheel utilizes a 3Å molecular sieve desiccant coating
to limit the risk of desiccant cross-contamination, which would otherwise
cause a portion of the exhaust air pollutants to be transferred, along with
the water vapor, to the fresh air stream.
The 3Å molecular sieve material utilized by SEMCO was developed
specifically for “selective adsorption” and has been successfully used for
decades by the petrochemical industry. Other desiccants like silica gel
and oxidized aluminum cannot provide selective adsorption.
Molecular sieves are structurally stable, chemically inert and have
a strong affinity for water vapor. This strong affinity for water vapor
produces the high rate of adsorption, which provides superior latent
transfer performance.
Non-oxidized Coated Media Construction
The EXCLU-SIEVE media is made from aluminum which is evenly
coated, prior to being formed into its honeycomb configuration, with
a dense layer of corrosion resistant desiccant. This extends the life of
the aluminum media substrate and enhances its structural integrity.
This is in sharp contrast to most other total energy wheels which are
produced by oxidizing the surface of the aluminum substrate to form
a crude desiccant, leaving the product susceptible to further oxidation
and diminishes its structural integrity.
Modular Media Sections with Aluminum Spoke Support
System
The media support system is made from aluminum extrusions. This
provides the substantial structural backbone required to withstand
the forces encountered during a wheel’s 10,000,000 annual revolutions
(assuming continuous operation).
The use of aluminum drastically reduces the weight of the rotor when
compared to a steel support system. The result is a more evenly balanced
rotor, which reduces wear and tear on the drive system and bearings.
The tolerances obtainable from an extruded media support structure
allow for the flattest possible sealing surface. This adds significantly to
the integrity of the total sealing system.
Service Free Drive and Control System
A responsive and maintenance-free drive system is an integral part of any
rotary heat exchanger. The drive system standard with any EXCLU-SIEVE
unit is an AC constant or variable speed system with drive belts.
4 • Energy Recovery Wheel Technical Guide
Non-wearing Extruded Labyrinth Seals
Rotor
Seal
EXCLU-SIEVE utilizes a four-pass labyrinth seal, which has been designed
to give optimum performance under the pressure conditions encountered
in this application. Since the seals never actually touch the rotating
surface, their life is indefinite. All seals are easily field adjustable. This
efficient sealing system increases performance and virtually eliminates
carryover of contaminants from the return air stream to the supply air
stream.
Tubular Steel Casing Construction
Air flowing between the rotor and
labyrinth seal expands repeatedly,
creating a pressure loss that forms an
effective seal and prevents air from
bypassing the rotor. The labyrinth
seal never touches the rotor.
To avoid deflection of the energy wheel casing due to the significant
torque imposed by the air pressure on the energy wheel surface, a tubular
steel framework is used. Casing deflection is undesired since it increases
the gap between the seals and the wheel surface causing excessive air
leakage.
Built-in Bearing Replacement System
The bearings used in the EXCLU-SIEVE units provide a long life with
minimal maintenance. The external pillow block bearings simplify any
replacements should this ever become necessary. The rotor remains in
the casing and none of the rotor or media has to be removed.
Optional Extended Service Contract
The EXCLU-SIEVE units are designed to provide long and reliable
operation. As a statement of our commitment to quality, the EXCLUSIEVE wheels are available with an optional extended service contract
to cover any unforeseen mechanical deficiencies or performance
degradations. The coverage period can be as long as five years.
Complete details can be obtained from your local SEMCO sales
representative.
Energy Recovery Wheel Technical Guide • 5
Recovering “Total Energy”
COA
Return Air (RA)
140
CEA
Exhaust Air (EA)
120
100
Supply Air (SA)
Outdoor Air (OA)
C: Cooling Mode
H: Heating Mode
CSA
80
CRA
60
40
HSA
HRA
20
HOA
HEA
0
20
40
60
80
100
Dry Bulb Temperature (°F)
6 • Energy Recovery Wheel Technical Guide
120
140
Humidity Ratio (grains of moisture per pound of dry air)
SEMCO EXCLU-SIEVE enthalpy exchanger recovers both sensible
(temperature) and latent (moisture) energy, and does so far more
effectively than other competitive offerings.
This performance edge is a result of EXCLU-SIEVE’s unique transfer
core. This “honeycomb like” media utilizes an aluminum substrate
coated with a fast acting, 3Å molecular sieve desiccant.
As the transfer core slowly rotates between the outdoor and return
air stream, the higher temperature air stream gives up its sensible energy
to the aluminum. This energy is then transferred to the cooler air stream
during the second half of the revolution.
Just as the temperature is captured and released, so is the moisture
(latent energy.) This is accomplished by the desiccant coating of the
wheel. The desiccant has a very strong affinity for water and an enormous
internal surface area to bind the water on its surface. Since the opposing
airstreams have different temperatures and moisture contents, their
vapor pressures on their surfaces differ. This vapor pressure differential
is the driving force necessary for the transfer of water vapor (See Figure
2.)
The ability to recover latent energy is one of the major benefits of
SEMCO’s EXCLU-SIEVE technology. It will do this both in the cooling
and the heating season. During the cooling season the outdoor air is
dehumidified and pre-cooled. (See Figure 2.) This significantly reduces
the cooling requirements of the conditioned space. In the heating season,
the process reverses and the outdoor air is humidified and preheated.
This reduces the costly humidification of ventilation air as well as the
heating requirements of the indoor space.
Latent recovery doubles the energy savings potential recognized with
the use of the sensible-only technology. It allows for cuts in chiller and
boiler capacities. System designs incorporating total energy recovery are
first cost equivalent to conventional designs when achieving the same
ventilation requirements and supply air conditions. In addition, they
provide operating cost savings year-in and year-out.
Figure 2. Typical operating
conditions encountered in the
cooling and heating mode of a total
energy recovery unit.
Recovering “Sensible Only”
Figure 3. Typical operating
conditions encountered in the
cooling and heating mode of a
sensible only energy recovery unit.
140
Return Air (RA)
Exhaust Air (EA)
120
CSA
COA
100
Supply Air (SA)
Outdoor Air (OA)
80
CRA
C: Cooling Mode
H: Heating Mode
CEA
60
40
HRA
HEA
20
HOA
0
HSA
20
40
60
100
80
Dry Bulb Temperature (°F)
120
Humidity Ratio (grains of moisture per pound of dry air)
The SEMCO TS series of sensible only energy wheels is specifically
designed to recover temperature only. The transfer media is not desiccant
coated but is polymer coated to avoid oxidation over time. Oxidation
reduces the structural integrity of the media over time and can also
cause modest latent transfer which is usually undesirable in sensible
only applications (please see “Sensible Wheel Applications” on page
23 of this brochure).
As shown in Figure 3, the air streams entering and leaving the sensible
only wheel are heated or cooled. Since no latent recovery is accomplished,
the moisture content of each airstream remains the same. A comparison
of the processes in Figures 2 and 3 reveals two key advantages offered
by total energy recovery. First, the total energy wheel recovers far more
energy due to the latent component. Second, the sensible wheel will
approach moisture saturation far more easily in the heating mode. This
can cause frost formation.
For these reasons, sensible wheels should only be used in applications
where moisture transfer is undesirable. Examples of such applications
include indirect evaporative cooling systems, desiccant cooling systems
and reheat wheels as used in the SEMCO Fresh Air Dehumidification In
every other way the SEMCO TS wheel is similar to the EXCLU-SIEVE
wheel and shares the benefits of superior performance and compact
design.
140
Energy Recovery Wheel Technical Guide • 7
Unit Selection
1 Wheel Selection
Wheel selection is based on face velocity. The energy recovery wheel
has been optimized for a face velocity of about 800. This achieves the
best balance between energy recovery effectiveness, pressure loss and
first cost.
Using the EXCLU-SIEVE Performance Chart (See Figure 4), find
the desired airflow volume on the left hand margin of the performance
chart. Selection is always based on the smaller of the supply or return
airflow when using unequal airflows. Read across until intersecting the
appropriate EXCLU-SIEVE TE3 model number, then read down to
obtain the face velocity. Reading down the chart further will give the
associated pressure loss for this face velocity. This procedure must be
repeated at the larger airflow volume to determine the pressure loss for
the opposite air stream in unequal flow applications.
AIRFLOW (SCFM X THOUSAND)
TOTAL ENERGY RECOVERY WHEEL SIZE
70
60
50
40
TE3-70
TE3-56
30
TE3-46
20
TE3-43
TE3-35
15
TE3-28
TE3-24
10
8
6
4
2
0
TE3-13
TE3-9
TE3-5
TE3-3
1100
500
700 800 900
600
1000
FACE VELOCITY (FPM)
400
.80
1.0 1.23
.60
.70
.90 1.10
.50
PRESSURE LOSS (IN. WG.)
.40
.35
EFFECTIVENESS (%)
(Rated at Minimum Airflow Volume)
TE3-18
95
FLOW
RATIO
Vmin/Vmax
90
85
.5
.6
.7
.8
.9
1.0
80
75
0
400
1100
500
600
700 800 9001000
FACE VELOCITY (FPM)
8 • Energy Recovery Wheel Technical Guide
Figure 4. Performance charts for
TE3 Series Total Energy Recovery
Wheels.
2 Unit Effectiveness
To calculate the supply and exhaust air conditions leaving the module,
the ASHRAE defined “unit effectiveness” must be determined as shown
in Figure 5.
Since the supply and exhaust air quantities often differ, the unit
effectiveness and the airflow ratio must be used in order to find the
efficiency (the amount of temperature or moisture transferred) for both
the supply and return air streams.
Figure 5. Definition of exchanger
heat transfer effectiveness.
The exchanger heat transfer effectiveness e is defined as the amount of
energy recovered, e.g. sensible or latent, divided by the maximum amount
of energy that could theoratically be recovered.
The supply air volume heat transfer effectiveness es is defined as
es =
Vs (X1 - X2)
Vmin (X1 - X3)
The return air volume heat transfer effectiveness er is defined as
er =
Vr (X4 - X3)
Vmin (X1 - X3)
Based on the above definitions, the supply air condition X2 can be calculated from
X2 = X1 - es
Vmin
Vs
(X1 - X3)
and the exhaust air condition X3 can be calculated from
V
X4 = X3 + es min (X1 - X3)
Vr
where Vs = Supply air volume, scfm
Vr = Return air volume, scfm
Vmin = Vr if Vr is smaller than Vs or Vmin = Vs if Vs is smaller than Vr
X = dry bulb temperture (°F) or moisture content (gr/lb) or enthalpy (Btu/lb)
The indices refer to the following airstreams, as indicated in the figure below:
1 = Outdoor air condition
2 = Supply air condition
3 = Return air condition
4 = Exhaust air condition
Return Air (3)
Exhaust Air (4)
Supply Air (2)
Outdoor Air (1)
Energy Recovery Wheel Technical Guide • 9
3 Unit Performance
Once the unit effectiveness is known, the equations provided by Figure 5
are used to calculate the dry bulb temperature (Tdb), moisture content
(w) and enthalpy (h) conditions leaving the exchanger.
NOTE: Wet bulb temperatures cannot be substituted for grains or
pounds of moisture per pound of dry air.
Exhaust Air Conditions
In most cases, the supply air leaving condition (as shown above) will
be required for both the heating and cooling modes. In many cases,
the exhaust air conditions must be calculated as well. This is required
for applications in colder climates, where ambient temperatures fall
below 15°F and where condensation and frost may form. (See page 19,
“Avoiding Frost and Condensation”.)
4 Purge Volume
A purge section is utilized to avoid carry-over of exhaust air into the
supply air stream. A small portion of outdoor air, in addition to that
required for space conditioning, is required for purge operation. Figure
8 on page 15 will provide the quantity of purge air required by your
application. This air volume must be added to the capacity of the
appropriate system fan(s) as shown by Figure 9 (indicated as Vp).
5 Chiller & Boiler Reduction
The SEMCO total energy recovery wheel reduces the energy required
to heat, cool and humidify the outdoor air volume to the return air
condition by as much as 90 percent. This results from its ability to recover
both latent and sensible energy at unprecedented efficiency levels.
This reduction in required chiller and/or boiler capacity should
be carefully evaluated when making final unit selections since even a
modest cut in the mechanical plant will offset the cost of the SEMCO
total energy recovery wheel.
Utilizing the equations provided below, the potential chiller and
boiler reduction can be estimated as follows.
Chiller Capacity = {supply air volume} ( EnthalpyIN - EnthalpyOUT )
4.5
12,000
in tons of cooling
Boiler Capacity = {supply air volume} ( EnthalpyIN - EnthalpyOUT )
4.5
33,000
in boiler horse power
The actual reduction made in the mechanical plant capacity, as
compared to the potential reduction as determined above, will change
from project to project. Factors such as weather data, hours of operation
and multiple modules on the project and the need for redundant capacity
must be carefully considered.
10 • Energy Recovery Wheel Technical Guide
Unit Selection Example
Consider an example with design conditions presented in Table 2. This
design data is the 0.4 percent wet bulb/mean coincident dry bulb data
for St. Louis, Missouri as published in the ASHRAE 2001 Fundamentals
Handbook, page 27.62.
Table 2. Example wheel selection
design data.
Design Data
Cooling
Heating
Supply Air Flow
12,000
scfm
12,000
scfm
Return Air Flow
10,800
scfm
10,800
scfm
Outdoor Air Conditions:
Temperature
Moisture Content
Enthalpy
90
133
45.2
°F
gr/lb
Btu/lb
2
4
1.1
°F
gr/lb
Btu/lb
Return Air Conditions:
Temperature
Moisture Content
Enthalpy
75
64
28.0
°F
gr/lb
Btu/
70
43
23.5
°F
gr/lb
Btu/lb
Purge Pressure Difference
3.0
in. w.g.
3.0
in. w.g.
1 Wheel Selection
Wheel selection is based on face velocity and the smaller of the return
or supply airflow rates. Based on the return airflow rate of 10,800 scfm,
the initial wheel size selected is TE3-13.
Figure 6 shows the basic selection procedure using the performance
chart. The first step is to find the return airflow volume value of 10.8
(corresponding to 10,800 scfm). Drawing a straight line across the graph,
we find that a TE3-13 wheel is sized for the optimal velocity between
700 and 900 fpm. Drawing a straight line from the intersection of the
10.8 line and the TE3-13 performance line, we read an approximate
velocity of 840 fpm through the wheel.
We can check this value by calculating it from the dimensional data
table on page 28. The flow area per face of the TE3-13 wheel is listed to
be 13.1 ft2. Thus, the return air volume of 10,800 scfm provides a face
velocity of 10,800 / 13.1 = 840 ft/min.
By extending the line from the face velocity axis to the pressure loss
scale, we find the pressure loss to be about 0.87 in.wg.
2 Determine Effectiveness
To determine unit effectiveness, we first calculate the airflow ratio. This
is the smaller of the supply or return air volumes divided by the larger of
the two. In this example, the airflow ratio is 10,800 / 12,000 or 0.9.
Once again, using the minimum airflow quantity, enter the
performance chart (See Figure 6), traverse to the right until intersecting
the desired model number, then read down until reaching the appropriate
airflow ratio curve. Finally, traverse left until intersecting the result
unit effectiveness value. For our example, the unit effectiveness is
approximately 0.8.
Energy Recovery Wheel Technical Guide • 11
AIRFLOW (SCFM X THOUSAND)
TOTAL ENERGY RECOVERY WHEEL SIZE
70
60
50
40
TE3-70
TE3-56
30
TE3-46
20
TE3-43
TE3-35
15
TE3-28
TE3-24
10
8
6
4
TE3-13
TE3-9
TE3-5
TE3-3
2
0
1100
500
700 800 900
600
1000
FACE VELOCITY (FPM)
400
.80
1.0 1.23
.60
.70
.90
.50
1.10
PRESSURE LOSS (IN. WG.)
.40
.35
EFFECTIVENESS (%)
(Rated at Minimum Airflow Volume)
TE3-18
95
FLOW
RATIO
Vmin/Vmax
90
85
.5
.6
.7
.8
.9
1.0
80
75
0
400
1100
500
600
700 800 9001000
FACE VELOCITY (FPM)
3 Calculate Performance
Having determined the unit effectiveness to be 0.8, we can now calculate
the supply air conditions for our example:
Supply Air Condition: Cooling Mode
X(Tdb)2 = 90°F - [.80 (10,800/12,000) (90°F - 75°F)]
X(Tdb)2 = dry bulb temperature = 79.2 °F
X(w)2 = 133 gr/lb. - [.80 (10,800/12,000) (133 - 64)]
X(w)2 = humidity ratio = 83.3 gr/lb
X(h)2 = 43.5 Btu/lb - [.80 (10,800/12,000) (43.5 - 28.0)]
X(h)2 = enthalpy = 32.3 Btu/lb
12 • Energy Recovery Wheel Technical Guide
Figure 6. Using the EXCLU-SIEVE
performance chart to select wheel
size and determine pressure drop and
wheel effectiveness.
Supply Air Condition: Heating Mode
X(Tdb)2 = 2°F - [.80 (10,800/12,000) (2°F - 70°F)]
X(Tdb)2 = dry bulb temperature= 51.0 °F
X(w)2 = 4 gr/lb - [.80 (10,800/12,000) (4 - 43) gr/lb]
X(w)2 = humidity ratio = 32.1 gr/lb
X(h)2 = 1.1 Btu/lb - [.80 (10,800/12,000) (1.1 - 23.5)]
X(h)2 = enthalpy = 17.2 Btu/lb
4 Determine Purge Volume
From Table 2 we know that the purge pressure difference is 3 in.wg.
Using the procedure described on page 15 and Figure 8, we estimate
the purge volume to be about 1,100 scfm.
5 Potential Chiller and Boiler Reduction
C = [12,000 scfm x 4.5 x (43.5 - 32.3) Btu/lb]/12,000 btu/ton
C = Chiller reduction capacity = 50.4 tons
B = [12,000 scfm x 4.5 x (17.2 - 1.1) btu/lb]/33,000 btu/bhp
B = Boiler reduction capacity = 26.4 boiler h.p.
Table 3 summarizes the results of our example.
Table 3. Calculated results of the
EXCLU-SIEVE wheel selection
example.
Calculacted Design Data
Cooling
EXCLU-SIEVE Model
Heating
TE3-13
Outdoor Air Face Velocity
1000 fpm
1000 fpm
Return Air Face Velocity
840 fpm
840 fpm
.80
.80
Supply Air Condition
Dry Bulb Temperature
Moisture Content
Enthalpy
79.2 °F
83.3 gr/lb
32.3 Btu/lb
51.0 °F
32.1 gr/lb
17.2 Btu/lb
Exhaust Air Condition
Dry Bulb Temperature
Moisture Content
87.0 °F
119.2 gr/lb
15.6 °F
11.8 gr/lb
Supply Air Pressure Loss
1.0 in.wg.
1.0 in.wg.
Return Air Pressure Loss
.88 in.wg.
.88 in.wg.
Purge & Seal Volume
1,100 cfm
1,100 cfm
4
4
Unit Effectiveness
Purge Index Setting
Energy Recovery Wheel Technical Guide • 13
Purge Section
Operation
As energy recovery wheel rotates from the exhaust air stream into the
supply air stream, a small amount of the exhaust air is traversing the
flutes of the wheel media as it passes by the seal separating the two air
streams. If this volume of exhaust air were allowed to mix with the clean
supply air stream, “cross-contamination” would occur.
Cross-contamination is virtually eliminated by a “purge section”,
which is an integral part of the casing design. The purge section utilizes
the pressure difference which exists between the outdoor and return
air streams to “purge” the transfer media with clean outdoor air prior
to its rotation into the supply air stream. Figure 7 provides a graphic
representation of the purge section operation.
The purge section is adjustable. This allows for optimizing the
required purge volume during system startup, regardless of the pressure
difference between the outdoor and return air streams (provided that
the return air pressure is lower than that of the outdoor air).
Figure 7. Schematic of the purge
operation.
Return Air
Exhaust Air
Purge Air
Supply Air
Outdoor Air
Rotation Direction
Selection
The required purge volume is determined by using the chart provided
in Figure 8.
First, the wheel size and the estimated pressure difference between
the outdoor and return air stream is determined. Traverse upward
until intersecting the appropriate wheel size. Reading to the left at
the intersection provides the air volume required for purge and seal
leakage.
After determining the difference between the return and outdoor
pressures, use Table 4 to determine the correct purge index.
14 • Energy Recovery Wheel Technical Guide
Figure 8. Chart to determine
required purge volume, based on
purge pressure and wheel size.
TE Wheel Purge and Seal Leakage
6,000
TE-70
Purge Volume (cfm)
5,000
TE-56
4,000
TE-46
TE-43
TE-35
3,000
TE-28
TE-24
TE-18
TE-13
TE-9
TE-5
TE-3
2,000
1,000
0
1
3
5
7
Purge Pressure (Poa - Pra) in.wg.
TS Wheel Purge and Seal Leakage
4,000
TS-70
3,500
TS-56
Purge Volume (cfm)
3,000
TS-46
TS-43
2,500
TS-35
TS-28
2,000
TS-24
TS-18
1,500
TS-13
TS-9
1,000
TS-5
TS-3
500
0
1
3
5
7
Purge Pressure (Poa - Pra) in.wg.
Table 4. Relationship between
pressure difference and purge
index.
Purge Index
Setting
Pressure Difference
Range (in.wg.)
TE
TS
7
0.00 - 0.99
0.00 - 0.4
6
1.0 - 1.5
0.5 - 0.7
5
1.6 - 2.0
0.8 - 1.0
4
2.1 - 3.0
1.1 - 1.5
3
3.1 - 6.0
1.6 - 3.0
2
6.1 - 10.0
3.1 - 5.0
1
> 10.0
> 5.0
Energy Recovery Wheel Technical Guide • 15
Fan Location Options
To assure effective purge operation and limit cross-contamination, the
pressure of the return air stream must be lower than that of the outdoor
air stream. As shown in Figure 9, three fan locations allow for effective
purge operation. The fourth fan arrangement, draw-through supply
and blow-through exhaust, must not be utilized if cross-contamination
is of concern. In that arrangement the pressure of the exhaust side will
always be greater than that of the return air and the purge section will
not operate under such conditions.
The purge and seal leakage air volume must be added to the
appropriate fan(s) depending on the fan arrangement. Figure 9 shows
which fans must be sized to handle this additional air volume (Vp) for
the different fan arrangements.
ARRANGEMENT 2
ARRANGEMENT 1
EXHAUST AIR = VR + VP
RETURN AIR = VR
EXHAUST AIR = VR + VP
PURGE = VP
OUTDOOR AIR = VS + VP
RETURN AIR = VR
PURGE = VP
SUPPLY AIR = VS
SUPPLY AIR = VS
OUTDOOR AIR = VS + VP
ARRANGEMENT 4
ARRANGEMENT 3
EXHAUST AIR = VR + VP
RETURN AIR = VR
PURGE = VP
OUTDOOR AIR = VS + VP
EXHAUST AIR = VR + VP
RETURN AIR = VR
PURGE = VP
SUPPLY AIR = VS
OUTDOOR AIR = VS + VP
SUPPLY AIR = VS
Drive Motor Location
The standard mounting location for the EXCLU-SIEVE drive motor is
in the supply air stream. The motor is located in the lower right hand
corner of the unit when looking at the conditioned air side.
16 • Energy Recovery Wheel Technical Guide
Figure 9. Fan arrangements for
proper purge operation.
Filtration Requirements
The EXCLU-SIEVE media is designed to induce laminar flow under all
conditions. This results in a flow profile, which causes airborne particles
smaller than approximately 800 microns, to pass freely through the rotor
media (See Figure 10).
Self-Cleaning Feature
As the EXCLU-SIEVE rotor operates between two opposing air streams,
the continuous reversal of airflow results in a very efficient “self-cleaning”
process. This process is further enhanced by the very high velocity of
the airflow in the purge section. As a result, only minimal filtration
is required for efficient operation of the EXCLU-SIEVE unit under
conditions encountered most typically in commercial and institutional
buildings.
Figure 10. Comparison of laminar
and turbulent flow profiles in the
transfer media.
LAMINAR FLOW: Particles pass through the flute at uniform velocity
- Flow velocity is maximum in the center of the flute
- Flow velocity is zero at the flute wall
TURBULENT FLOW: Particles pass through the flute at random velocities
- Flow velocity is not uniform through the flute
- Particles hit the flute wall and may collect on the wall
Outdoor and Supply Air streams
An insect screen should be placed behind the outdoor air intake louver
in order to prohibit large items such as insects, leaves and debris from
entering the EXCLU-SIEVE energy wheel. It is also recommended that
low efficiency (20 - 30 percent), cleanable or pleated filters be provided
prior to the EXCLU-SIEVE energy wheel.
Return Air stream
For applications where the return air is relatively clean (such as general
office areas), no filtration is required prior to the EXCLU-SIEVE energy
wheel. In industrial or institutional applications where the return air
contains bacteria, lint, oil mist, or animal hair, the appropriate filtration
must be incorporated. Please contact SEMCO Incorporated for specific
recommendations.
Energy Recovery Wheel Technical Guide • 17
Odors and Contaminants
The EXCLU-SIEVE product was specifically developed for applications
involving contaminated air streams. Its field adjustable purge section and
four pass non-wearing labyrinth sealing system limits “air stream crosscontamination” to less than .04 percent of the exhaust air concentration
by volume.
“Selective adsorption,” the ability to transfer water vapor to and from
the exhausted air stream while allowing other gaseous contaminants to
pass unadsorbed, is a necessity for most all energy recovery applications.
Re-circulating some portion of these contaminants back to the space
is undesirable since it reduces the dilution ventilation efficiency
(requiring more ventilation air), can cause buildup of odors and, in some
applications, result in an unhealthy environment.
The EXCLU-SIEVE wheel provides selective adsorption through
the application of a 3-angstrom molecular sieve desiccant material.
Desiccants such as silica gel, activated alumina, oxidized aluminum,
and even other types of molecular sieves, do not provide selective
adsorption.
Adsorbents trap water vapor and/or other components within their
complex internal surface area, which is comprised of a network of holes
or “pores.” “Molecular sieves” are different than all other desiccants.
Their “pore diameter” is completely uniform and in the case of a 3Å
molecular sieve, it can be controlled to precisely 3 angstroms. This
configuration excludes the adsorption of molecules that have a kinetic
diameter greater than 3 angstroms (practically all contaminants) while
having a strong affinity for and adsorbing water vapor (2.8 angstroms).
Pollutant Concentration*
Measured CrossContamination
20 ppm
None
Methyl-Isobutyl-Ketone
1840 ppb
None
Xylenes
7100 ppb
None
Carbon Dioxide
500 ppm
None
Propane
82 ppm
None
Sulfur Hexafloride
212 ppm
None
Water Vapor
4000 ppm
80%
Pollutant Tested
Isopropanol
*Concentrations selected by GTRI to reflect worst case for typical application
18 • Energy Recovery Wheel Technical Guide
Table 5. A summary of independent
testing conducted by the Georgia
Tech Research Institute confirming
the ability of the EXCLU-SIEVE
wheel to avoid contaminant
cross-contamination. For more
information, request a copy of the
GTRI cross-contamination report.
Wheel Speed Control
An important design advantage provided by rotary energy recovery
technology is the ability to control performance by varying the rotational
speed of the rotor media. EXCLU-SIEVE utilizes an A/C frequency
inverter and temperature sensors to control the leaving air temperature
during the various modes of operation.
80
20
70
Temperature Control
Mode
Economizer
Mode
75
60
Effectiveness (%)
Wheel Rotational Speed (rpm)
Figure 11. Example of wheel speed
modulation.
50
40
70
30
20
60
10
50
0
25
-10 0 10 20 30 40 50 60 70 80 90
Outdoor Temperature (°F)
Avoiding Frost Formation and Condensation
For applications in extremely cold outdoor air conditions, the risk of
frost formation should always be analyzed. EXCLU-SIEVE provides
a significant advantage over sensible only recovery (temperature only)
devices. It dehumidifies the exhaust air stream as it is cooled. This
prohibits the exhaust air stream from reaching saturation under all but
extreme conditions. If the saturation condition is avoided, frost will not
form on the exchange surface.
Frosting can also be avoided during the extreme conditions by
monitoring the exhaust air temperature and reducing the recovery
effectiveness by the amount required to avoid saturation. Additionally,
frosting can be avoided by preheating the outdoor air, heating the return
air or bypassing the exchanger. Preheating or speed control are the most
common methods.
Energy Recovery Wheel Technical Guide • 19
Preheating to Avoid Frost Formation
Applications that involve humidity control during the heating season
(above 30 percent relative humidity) and when the outdoor air
temperature is frequently below 0°F, preheating the outdoor air to avoid
frost formation is usually the most energy efficient approach. This is
because the total energy wheel is allowed to operate at full recovery on
very cold days, thereby providing for maximum humidification recovery.
Reducing the wheel speed to cut temperature recovery also reduces the
latent recovery.
The preheat temperature required is determined by:
1. Locating the return air condition on a psychrometric chart
2. Drawing a line tangent to the saturation curve
3. Connecting to the heating design outdoor air humidity content
4. Reading the dry bulb intercept value, as shown in Figure 12,
line RA-OA1
5. Preheating the outdoor air to the dry bulb intercept value, as
shown by Figure 12, line OA2-OA1
Controlling Wheel Speed To Avoid Frost Formation
Applications where humidification is not provided during the heating
season (below 30 percent RH during cold days) and where the number
of hours below 0°F each year are few, varying wheel speed to avoid frost
formation is probably the best choice.
The dew point control set-point is determined by:
1. Locating the return air condition (RA) that exists when the
winter outdoor air design condition is reached.
Condition OA1: No frosting at full recovery
As the outdoor air temperature drops (OA1 to OA2),
speed modulation slows the wheel down reducing
the heat transfer effectiveness thus ensuring that
exhaust air does not reach saturation
(condition EA2). This eliminates both
condensation and frosting.
50
30
Exhaust Air EA1
10
Outside Air OA1
0
10
5
20
22
40
30
50
35
Dry Bulb Temperature (°F)
20 • Energy Recovery Wheel Technical Guide
Humidity Ratio
40
20
-10
52
(grains of moisture per pound of dry air)
Return Air RA
Exhaust Air EA2
Outside
Air OA2
Figure 12. Example of preheat or
wheel speed modulation to avoid
frost formation.
60
2.5
60
70
72
80
2. Plot the RA point on the psychrometric chart and draw a line between
it and the winter design point.
3. Determine the higher dry bulb temperature at which this line
intercepts the saturation curve (EA2 on Figure 12).
4. Add 2°F to this temperature and this becomes the control (winter)
set-point.
Avoiding Overheating (Economizer Cycle)
During the Spring and Fall seasons, when the outdoor air temperature
is close to that being supplied to the space, the EXCLU-SIEVE control
system will slow the media rotational speed in response to a supply air setpoint. This decreases the recovery effectiveness by the amount required
to provide the desired supply air temperature (See Figure 11).
Automatic Summer-Winter Change Over
By monitoring the difference between the outdoor air condition and
the return air condition, the cooling mode is selected whenever the
outdoor air is warmer than the return air. This calls for full recovery
effectiveness once again. Full recovery is maintained automatically until
the outdoor air condition drops to the point where the economizer cycle
is most efficient.
Condensation on Sensible Only Wheels
Variable wheel speed and reheat approaches can be used for sensible
energy wheels. Consult SEMCO Incorporated for assistance.
Energy Recovery Wheel Technical Guide • 21
Sensible Wheel Performance
The performance chart shown below presents the performance for
the SEMCO TS series of sensible (temperature transfer only) energy
recovery wheels. This performance chart would be utilized along with
the selection procedure, outlined on pages 8 through 10 of this brochure
for selection of a TE3 series total energy (temperature and moisture
transfer) wheel, to calculate supply and exhaust air efficiencies, dry
bulb temperature conditions and pressure loss data. Since sensible only
wheels are not designed to transfer moisture, the supply and exhaust air
humidity content is equal to that of the outdoor and return airstreams
respectively. Some moisture will be transferred if condensation occurs
on the surface of the TS wheel and this situation should be avoided in
most cases (See “Condensation and Frosting”).
AIRFLOW (SCFM X THOUSAND)
SENSIBLE ONLY ENERGY RECOVERY WHEEL SIZE
70
60
50
40
30
TS-70
TS-56
TS-46
TS-43
20
TS-35
15
TS-28
TS-24
10
8
6
4
2
0
TS-13
TS-9
TS-5
TS-3
1100
500
700 800 900
600
1000
FACE VELOCITY (FPM)
400
.80
1.0 1.23
.60
.70
.90 1.10
.50
PRESSURE LOSS (IN. WG.)
.40
.35
EFFECTIVENESS (%)
(Rated at Minimum Airflow Volume)
TS-18
FLOW
RATIO
Vmin/Vmax
95
90
.5
.6
.7
.8
.9
1.0
85
80
75
0
400
1100
500
600
700 800 9001000
FACE VELOCITY (FPM)
22 • Energy Recovery Wheel Technical Guide
Figure 13. Performance charts for
TS series sensible only recovery
wheels.
Sensible Wheel Applications
Sensible wheels should only be applied to applications where the
transfer of moisture is undesirable. This is due to the fact that the
EXCLU-SIEVE total energy wheel is approximately the same cost, but
offers the advantage of latent recovery and the associated frost control
advantage, which makes it the product of choice for even heating mode
only applications.
Examples of sensible only applications include indirect evaporative
cooling, direct/indirect evaporative cooling, desiccant based cooling
(second wheel) and in the reheat position in the SEMCO EPD system
concept.
The common element for all of these applications is the importance
of avoiding any moisture transfer. To avoid moisture transfer, it is critical
that the aluminum wheel media be carefully coated to avoid the inherent
oxidation that would otherwise take place over time, turning a sensible
wheel into a moderately effective latent wheel. As a result, all SEMCO
TS sensible only wheels are made from a polymer coated aluminum
substrate, which is carefully coated prior to being formed into the
honeycomb transfer media.
Condensation & Frosting
Unlike the EXCLU-SIEVE total energy wheel where the supply air
leaving the wheel follows a straight path between the return air and the
outdoor air, a plot of the supply air condition leaving a sensible only
wheel on a psychrometric chart resembles that of a chilled water coil.
Since no moisture is transferred by a sensible wheel, the temperature
of the air streams are changed as the sensible energy is exchanged, but
the moisture level remains constant unless the supply air or exhaust
airstreams are cooled to below their dew points.
If this occurs, one of three things will happen:
1. If the exhaust air stream is cooled to less than approximately 20°F
below its dew point, and if the leaving temperature of the air stream
is above 32°F, a thin film of condensate will form on the vast surfaces
of the wheel media, and this condensate will re-evaporate into the
warmed supply air stream. If this moisture transfer is a problem, it can
best be avoided by limiting the exhaust side recovery with controls
to vary wheel speed based on a dew point temperature sensor.
2. If the exhaust air stream is cooled more than 20°F below its dew
point, and if the leaving temperature of the air stream is above
32°F, some condensate will re-evaporate into the warmed supply air
stream and the remainder will blow off of the wheel surface. This
is not advised and, as a result, the variable wheel speed controller
should once again be applied.
3. If the exhaust air stream is cooled below 32°F and reaches its dew
point, frost may form on the face of the wheel, reducing airflow.
Preheat should be applied in this case to avoid cooling the exhaust
air stream below its dew point.
Energy Recovery Wheel Technical Guide • 23
Cleaning The Wheel Media
The SEMCO EXCLU-SIEVE energy recovery wheel has been designed
so that a laminar flow is maintained within the transfer media at all
operating conditions. This means that the air and all other particles in
the air stream pass straight through the wheel.
Due to the laminar flow profile through the EXCLU-SIEVE energy
wheel, any collection of dust or particulate matter will occur at the
entering and leaving edges of the transfer media. Such buildup can
usually be vacuumed, purged with compressed air or wiped from the
rotor surface. In rare cases where a more thorough cleaning is required,
low temperature steam or hot water and detergent may be used. Consult
SEMCO for instructions when using cleaning methods other than
compressed air or vacuuming.
Installation Guidelines
Provisions should be made to allow access to all four sides of the module
to facilitate seal adjustment and routine inspection.
Locate the A/C inverter control panel in a dry, conditioned space,
which is clearly visible to the operations personnel. A rotation detector
should be included as a part of the control package for all critical
applications.
The purge section must always face the conditioned airside of the
system. Rotation is such that a spot on the media in the return air section
would rotate towards the purge section without first passing into the
supply section.
Carefully review the purge, fan location and filter recommendations
covered by this brochure prior to completing any design. Select the
appropriate control option for the application. Please consult SEMCO
for any additional design assistance required.
Consult SEMCO for design recommendations with applications
involving hazardous contaminants, exhaust air temperatures in excess
of 180°F and/or high humidity conditions (drying ovens, swimming
pools, etc.).
24 • Energy Recovery Wheel Technical Guide
Typical Wiring Schematic
RED
BLACK
GREEN
L1
GND
ƒIN4
GND
ƒIN1
INDEECO
ROTATION
DETECTOR
COM
120V
ROTATION DETECTOR SENSOR
N
ƒIN3
GND
24VAC POWER BY OTHERS OR USE OF OPTIONAL
TRANSFORMER SHOWN ABOVE
ƒIN2
GND
H
N
RESET
CR1
H
H
ERW
AL ARM
N
N
24/24 ISO XFMR
20VA
H
N
UNUSED A L ARM
CONTACT FOR
FIELD USE. MAY
BE FIELD WIRED
TO IN6 ON I/O
ZONE 583
N
X
+12V
Rnet -
Rnet +
Gnd
JUMPER
SETTINGS
RED
GREEN
WHITE
BLACK
YASKAWA V1000 VFD ƒ
Err
CR
IN-1
2032
IN-2
Sense
+12V
Rnet-
23
Rnet
Rnet -
RED
Gnd
IN-2
Gnd
IN-3
Gnd
IN-4
Gnd
IN-5
IN-6
A1
AC
S1
Thermistor/dry
contact
0-5Vdc
Thermistor/dry
contact
0-5Vdc
On
Selection
Communications
Comm
EIA-485
BACnet
Over
ARC156
Inputs 1 & 2
0-5V, therm,
or dry
BAUD
RATES
9600
SW1
SW2
Off
Off
19.2 K
Off
38.4 K
On
76.8 K
On
On
Off
On
Selector
DIP Switch
PROTOCOLS
BACnet
MS/TP
N2
SW3
SW4
Off
Off
On
Off
Off
On
I/0 ZONE 583
Gnd
AO-2
Gnd
AO-1
CR1
DO-5
Outputs
24V
Max,
1A Max
Inputs 5 & 6
Therm, dry, or
LStat
Gnd
AO-3
Modbus
Inputs 3 & 4
Therm or dry
24 Vac,
50-60 Hz
20VA, 0.83A
Gnd
IN-5 IS FACTORY
JUMPERED AND M AY BE
FIELD WIRED AS REMOTE
START/STOP BY OTHERS
IN-8
1
Access
+12V
IN-1
Gnd
4
23
GREEN
+3V
4
3
2
1
Gnd
Local
X
IN-7
Pot.
Only
3
23
Gnd
Rnet +
1
Run
+
Rnet+
BLACK
WHITE
2
Hot
24 Vac
Pwr
O
N
Tens
Ones
456
78
901
901
456
78
23
78
Batt
-
901
456
78
901
456
Shield
Ground
Lstat
IN-5
2
Net -
Rnet
Format
Short
pins
R
S
T
U
V
W
E
Tx
Comm
Rx
Net +
SC
Lstat
BT485
0-10 VDC ANA LOG SPEED
SIGNAL AND S TART/STOP
CONTACT TO BE FIELD WIRED
FROM TERMINAL B LOCK TO VF D
N
DO-4
DO-2
CR
1
DO-1
Power for D.O.'s
'S' LEG USED
ON 3ph ONLY
DO-3
BUS
MOTOR
H
LED
200-230/1/60
200-230/1/60
420-480/3/60
420-480/3/60
* THROUGH WHEEL SIZE 35
** WHEEL SIZE 43 AND L ARGER
ƒ Shipped loose for field mounting
MAX. INPUT
MCCB RATING
15 AMP
15 AMP
15 AMP
15 AMP
VFD S/S
200-230V, 50/60Hz, 1ph in /3ph out
420-480V, 50/60Hz, 3ph
H
H
H
N
N
N
FR
FC
S1
SC
POWER
CIMR-V7AM20P4*
CIMR-V7AM20P7**
CIMR-V7AM40P2*
CIMR-V7AM40P7**
COM
H
H
H
N
N
N
FR
FC
S1
SC
INVERTER MODEL
24V
GND
IN-6 MAY BE FIELD WIRED
TO ROTATION DETECTOR
AL ARM CONTACT
0-10VDC
REQUIRED BRANCH
CIRCUIT PROTECTION
BY OTHERS
TERMINAL STRIP TS-1,
FIELD WIRING
CONNECTIONS
Field Wiring
Factory Wiring
Energy Recovery Wheel Technical Guide • 25
Mounting Arrangements
The EXCLU-SIEVE units can be mounted in six different positions
(see Figure 14). The number of support points required for horizontal
mounting may vary depending on the size of the unit. Consult SEMCO
for support details.
When installing an EXCLU-SIEVE unit, the purge section must
always face the conditioned airside of the system. Rotation is such that
a spot on the media in the return air section would rotate towards the
purge section without first passing into the supply section.
Arrangement A
Arrangement C
Arrangement E
SA
SA
RA
RA
RA
SA
Arrangement B
SA
RA
Arrangement D
Arrangement F
RA
OA
EA
SA
RA: Return Air
SA: Supply Air
OA: Outside Air
EA: Exhaust Air
Wheel Drive Options
There are three different control options that can be ordered with the
Total Energy Recovery unit:
1) No Controls:
Power is connected directly to the motor. The wheel rotates at a constant
speed (20 rpm).
2) Variable Frequency Drive (VFD) ONLY:
SEMCO ships a pre-qualified variable frequency drive with the unit
for field mounting. The VFD has the same voltage as the motor and
can modulate the motor from 20 rpm to 1/5 rpm. Four temperature
sensors (one in each air stream), and a temperature controller must be
field provided, mounted, wired and programmed.
26 • Energy Recovery Wheel Technical Guide
Figure 14. Wheel mounting
arrangements.
3) Variable Frequency Drive (VFD) & Controls:
SEMCO ships the same variable frequency drive mentioned above,
along with four temperature sensors and a solid-state controller with
the module. All of these accessories are to be field mounted and wired.
The advantage of this option is that it is a pre-packaged stand-alone
system.
A rotation detector can be ordered with any of the control options
mentioned above. This rotation detector will ship with the unit for
field mounting.
Ordering Key
T __-__-_-_-_-_-_-_
TYPE OF UNIT
TE3: Total Energy Wheel
TS: Sensible Only Energy Wheel
UNIT MODEL NUMBER
3, 5, 9, 13, 18, 24, 28, 35, 43, 46, 56, 70
PURGE INDEX SETTING
0, 1, 2, 3, 4, 5, 6, 7
UNIT MOUNTING ARRANGEMENT
A, B, C, D, E, F
MOTOR TYPE
0: 208/230V/1Ph/60Hz, Variable Speed, With Inverter
1: 208/230V/3Ph/60Hz, Variable Speed, With Inverter
2: 460V/3Ph/60Hz, Variable Speed, With Inverter
3: 208-230V/3Ph/60Hz, Variable Speed, Without Inverter
4: 460V/3Ph/60Hz, Variable Speed, Without Inverter
7: 208-230V/3Ph/60Hz, Constant Speed
8: 460V/3Ph/60Hz, Constant Speed
Note: Not all motors are available in all sizes
TEMPERATURE CONTROLLER
0: No controller
1: 24V/1Ph with 4 Point Sensors
2: 120V/1Ph with 4 Point Sensors
3: 24V/1Ph with Averaging SA & EA Sensors
4: 120V/1Ph with Averaging SA & EA Sensors
ROTATION DETECTOR
0: No rotation detector
1: 24V/1Ph
2: 120V/1Ph
ANTI REVERSE BEARING
0: No
1: Yes (not available in sizes 3, 5 or 9)
Energy Recovery Wheel Technical Guide • 27
Performance Data For TE3 & TS Wheels
Wheel Size
Effi- Press.
Velocity
ciency Drop
fpm
in. wg
%
3
5
9
13
18
24
28
35
43
46
56
70
88.0
0.29
840
1,590
2,580
3,930
5,430
7,140
8,490
10,560
12,870
13,920
16,800
21,120
400
86.0
0.37
1,120
2,120
3,440
5,240
7,240
9,520
11,320
14,080
17,160
18,560
22,400
28,160
500
82.5
0.45
1,400
2,650
4,300
6,550
9,050
11,900
14,150
17,600
21,450
23,200
28,000
35,200
600
80.5
0.56
1,680
3,180
5,160
7,860
10,860
14,280
16,980
21,120
25,740
27,840
33,600
42,240
700
78.5
0.67
1,960
3,710
6,020
9,170
12,670
16,660
19,810
24,640
30,030
32,480
39,200
49,280
800
77.0
0.79
2,240
4,420
6,880
10,480
14,480
19,040
22,640
28,160
34,320
37,120
44,800
56,320
900
76.0
0.94
2,520
4,770
7,740
11,790
16,290
21,420
25,470
31,680
38,610
41,760
50,400
63,360
1000
74.5
1.05
2,800
5,300
8,600
13,100
18,100
23,800
28,300
35,200
42,900
46,400
56,000
70,400
1100
73.5
1.18
3,080
5,830
9,460
14,410
19,910
26,180
31,130
38,720
47,190
51,040
60,600
77,440
Airflow Rate (in cfm)
300
Unit Dimensions
Wheel Sizes 13 - 70
Wheel Sizes 3, 5, 9
Mounting
Arrangements
A, B, C, D, E, and F
(see Figure 14)
Weather Air Side
B
W
C
C
A
A
B
D
D
W
A
Flow
Net Wt.
Nomiarea/
(lbs)
nal
cfm
side ft2
Wheel
Size
A
B
C
W
3
39.8
48.8
16.9
20.0
380
2.8
2,000
5
51.8
58.2
22.9
20.0
520
5.3
4,000
9
63.8
70.2
28.9
20.0
700
8.6
7,000
Wheel Size
A
B
C
D
W
Net Wt.
(lbs)
Flow area
/side, ft2
Nominal
cfm
13
75.8
33.8
40.0
36.9
21.0
1,070
13.1
10,500
18
87.8
39.8
46.0
42.9
21.0
1,300
18.1
15,500
24
99.8
45.8
52.0
48.9
21.0
1,640
23.8
19,000
28
111.8
49.8
59.0
54.4
23.0
2,640
28.3
22,500
35
123.8
55.8
65.0
60.4
23.0
3,000
35.2
28,000
43
135.8
61.8
71.0
66.4
23.0
3,390
42.9
34,000
46
141.0
64.4
73.6
69.0
23.0
3,570
46.2
37,000
56
154.0
70.9
80.1
75.5
23.0
4,030
56.0
45,000
70
171.5
79.6
88.9
84.3
23.0
4,680
70.4
56,000
All dimensions in inches
28 • Energy Recovery Wheel Technical Guide
Sample Specification
A. Total Energy Recovery Wheel Unit - The rotor media shall be made of aluminum,
which is coated to prohibit corrosion. All media surfaces shall be coated with a nonmigrating solid adsorbent layer prior to being formed into the honeycomb media
structure to ensure that all surfaces are coated and that adequate latent capacity is
provided. The media shall have a flame spread of less than 25 and a smoke developed
of less than 50 when rated in accordance with ASTM E84.
The faces of the total energy recovery wheel shall be sealed with a two-part polymer
acid resistant coating to limit surface oxidation. The media face coating shall also
include a proprietary Teflon-based anti-stick additive shown, by independent testing,
to effectively limit the collection of dust or smoke particulate and to aid in the surface
cleaning process should cleaning be required.
The entire recovery wheel media face shall be treated with Avron46, and shall exhibit
effective antimicrobial action, supported by independent test data. Any antimicrobial
agent used must, by law, carry an EPA registration for use in duct systems. All desiccant
surfaces within the transfer media shall also exhibit bacteria-static properties as
supported by independent testing.
The desiccant shall be inorganic and specifically developed for the selective adsorption
of water vapor. The desiccant shall utilize a 3A molecular sieve certified by the
manufacturer to have an internal pore diameter distribution which limits adsorption to
materials not larger than the critical diameter of a water molecule (2.8 angstroms).
Submit certification by a qualified independent organization documenting equal
sensible and latent recovery efficiencies conducted in accordance with ASHRAE 8478P and the results presented in accordance with ARI 1060 standards.
An independent wheel test from a credible test laboratory shall document that the
desiccant material utilized does not transfer pollutants typically encountered in the
indoor air environment. The cross-contamination and performance certification
reports shall be provided upon written request for engineering review.
Media Cleaning - The media shall be cleanable with low-pressure steam (less than 5
PSI), hot water or light detergent, without degrading the latent recovery. Dry particles
up to 800 microns shall pass freely through the media.
Purge Sector - The unit shall be provided with a factory set, field adjustable purge
sector designed to limit cross contamination to less than .04 percent of that of the
exhaust air stream concentration when operated under appropriate conditions.
Rotor Seals - The rotor shall be supplied with labyrinth seals only, which at no time
shall make contact with any rotating surface of the exchanger rotor face. These multipass seals shall utilize four labyrinth stages for optimum performance.
Rotor Support System - The rotor media shall be provided in segmented fashion to
allow for field erection or replacement of one section at a time without requiring side
access. The media shall be rigidly held in place by a structural spoke system made
of extruded aluminum.
Energy Recovery Wheel Technical Guide • 29
Rotor Housing - The rotor housing shall be a structural framework, which limits the
deflection of the rotor due to air pressure loss to less than 1/32”. The housing is
made of galvanized steel to prevent corrosion. The rotor is supported by two pillow
block bearings which can be maintained or replaced without the removal of the rotor
from its casing or the media from its spoke system.
Optional Temperature Control Panel - Variable speed control shall be accomplished
by the use of an A/C inverter. The inverter shall include all digital programming
with a manual speed adjustment on the front of the inverter. The drive system shall
allow for a turndown ratio of 100:1 (20 rpm to 1/5 rpm). The control system shall
include four linearized thermistor sensors as follows:
• Supply air temperature sensor;
• Differential summer/winter changeover sensors mounted in the outdoor and return
air streams;
• Frost prevention sensor located in the exhaust air stream.
Optional Rotation Detector - A 24VAC rotation detector sensor will be mounted at
the wheel and wired to the detector in the main electrical panel.
Optional Digital Performance Display Module - Digital read out confirming the
effectiveness of the energy wheel via temperature readings recorded by these sensors
and control set-points shall be displayed by the control panel.
B. Warranty - The unit manufacturer shall warrant to the Buyer that for a period of
eighteen months from the date of shipment the goods to be delivered to the Buyer
shall in all material respects be free from defects in material and workmanship when
used in a proper and normal manner. Should any failure to conform to the above
appear within eighteen months after the date of shipment, the unit manufacturer
shall upon prompt notification thereof during the Warranty Period and confirmation
to the unit manufacturer’s satisfaction that the goods have been stored, installed,
operated and maintained properly and in accordance with standard industry practice,
correct the non-conformity at the unit manufacturer’s option either by repairing
any defective part or parts or by making available at the unit manufacturer’s plant
a repaired or replacement part.
How to Reach SEMCO
You can reach SEMCO Incorporated by phone, fax, mail, or e-mail.
SEMCO Incorporated
1800 East Pointe Drive
Columbia, MO 65201-3508
888-4SEMCOINC (888-473-6264)
573-443-1481
Fax: 573-886-5408
e-mail: sales.semco@flaktwoods.com
For information about SEMCO Incorporated, our desiccant wheel products and
services, please point your web browser to www.semcoinc.com. There, you will also
find the latest news from SEMCO and examples of how SEMCO’s energy recovery
systems are being applied on a daily basis in a multitude of applications.
30 • Energy Recovery Wheel Technical Guide
Wheel
Configuration
Checklist
Desiccant Wheel Products
JOB NAME
UNIT TAG
WHEEL
ARRANGEMENTS
DATE
Arrangement A
T __-__-_-_-_-_-_-_
RA
SA
Arrangement B
TYPE OF UNIT
TE3: Total Energy Wheel
TS: Sensible Only Energy Wheel
RA
SA
UNIT MODEL NUMBER
3, 5, 9, 13, 18, 24, 28, 35, 43, 46, 56, 70
PURGE INDEX SETTING
0, 1, 2, 3, 4, 5, 6, 7
UNIT MOUNTING ARRANGEMENT
A, B, C, D, E, F
Arrangement C
MOTOR TYPE
0: 208/230V/1Ph/60Hz, Variable Speed, With Inverter
1: 208/230V/3Ph/60Hz, Variable Speed, With Inverter
2: 460V/3Ph/60Hz, Variable Speed, With Inverter
3: 208-230V/3Ph/60Hz, Variable Speed, Without Inverter
4: 460V/3Ph/60Hz, Variable Speed, Without Inverter
7: 208-230V/3Ph/60Hz, Constant Speed
8: 460V/3Ph/60Hz, Constant Speed
Note: Not all motors are available in all sizes
SA
RA
Arrangement D
TEMPERATURE CONTROLLER
0: No controller
1: 24V/1Ph with 4 Point Sensors
2: 120V/1Ph with 4 Point Sensors
3: 24V/1Ph with Averaging SA & EA Sensors
4: 120V/1Ph with Averaging SA & EA Sensors
RA
SA
ROTATION DETECTOR
0: No rotation detector
1: 24V/1Ph
2: 120V/1Ph
Arrangement E
ANTI REVERSE BEARING
0: No
1: Yes (not available in sizes 3, 5 or 9)
SA
RA
Arrangement F
Please check one:
Hold for Approval
Signature
OA
Release for Production
EA
RA: Return Air
SA: Supply Air
OA: Outside Air
EA: Exhaust Air
Energy Recovery Wheel Technical Guide • 31
Notes
32 • Energy Recovery Wheel Technical Guide
Notes
Energy Recovery Wheel Technical Guide • 33
Certified, Specified, Proven™
A Fläkt Woods Company
1800 East Pointe Drive
Columbia, Missouri 65201-3508
1-888-4SEMCOINC (1-888-473-6264)
573-443-1481
Fax: 573-886-5408
E-mail: sales.semco@flaktwoods.com
www.semcoinc.com
W AB 005.9 0909 (supersedes W AB 005.8 1107)
0410 1K G
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