installation manual - Hot Sun Industries Inc
Hot Sun Industries Inc
103-13200 Kirkham Way,
Poway CA 92064
858-683-0800 e-mail: [email protected]
see manual addendums for specific roof types
 2015 copyright Hot Sun Industries Inc (USA) and Hot Sun Industries Ltd (Canada)
Ensure all piping slopes downhill to drain and all plumbing drains are left open through freezing
conditions. Note: Solar heaters are solar coolers at night. Air temperature only has to drop to 42F for water
to freeze inside a solar cooler Our flexible fin-tubing can freeze full of water without concern. This is a
major advantage of this technology. Plumbing and header manifolds are not flexible and are vulnerable.
Drains on flat rooftops should be closed once plumbing is emptied to prevent water getting back in and
freezing. See repair manual if damage occurs.
Don't attempt this installation if you are not fully capable of working safely on the roof or hillside or
wherever you will be working. Falls from roofs are a common and serious workplace accident. The use of
safety equipment including body harnesses, lanyards and lifelines, ladders, and hazardous chemicals
require training and certification. Hot Sun will not be held accountable for injuries. We require that you
take all responsibility for learning how to use and for using correctly all safety equipment and chemicals
and tools. If you aren’t qualified and experienced working at height, and doing this kind of work, we
strongly urge you to hire a contractor that is. Read all warning labels on all adhesives and cements used in
this installation. Wear gloves and safety glasses and don’t work alone. The adhesive that joins the fin tubes
to the headers is cyanoacrylate aka superglue. The fumes will burn your eyes and the adhesive can stick
your skin to itself or the materials being adhered.
When we “designed” your system we did so based on pressure. If the pressure after your filter was
expected to be low relative to the height of the collectors we specified the plumbing diagram at the left
below and if the pressure is high and we had an available place to return pressure regulated (low pressure)
water from solar without having to re-pressurize it, then we specified something like the diagram below to
the right. The common theme is we want solar to operate under minimal pressure.
is the full lesson on this. Fig 1b pressure designs are a last resort. Many other plumbing designs and
variations are possible. Don’t “design” this yourself unless you fully understand .
The plumbing specification custom to your unique application is Hot Sun’s responsibility and you paid for
it in the purchase price of the materials.
Fig 1a: General Schematic of Solar Pool Heater- low pressure design on left and a common high pressure
design (Fig 1b) on right.
The diagrams above show typical plumbing schemes for automatically controlled solar pool heaters. When
the roof sensor gets warmer than the pool temperature sensor (plumbed right after the check valve, CV1)
and the pool is colder than the set point you’ve dialed in (the maximum pool temperature), the motorized
valve will turn and divert flow to the bottom of the bank of solar collectors. The water rises up (or
sideways) though the collectors flushing all the air out to the return pipe and back to the pool. When solar
turns off after the pool is warm or the solar day is over, the water level drops. The water level will not drop
if the collectors are under pressure. Always verify this on a new installation by carefully following the "Start
Up Instructions”. The check valve CV1 prevents the water from going backwards through the filter and
pump when the pump is turned off. Normally we’ll put a clear check valve CV2 on the return from solar
pipe just so you can see the flow. CV2 also isolates solar when solar is off. CV2 must be mounted with the
flow sideways or up. If it mounted so the flow goes down, gravity will hold the flap open and it will not
Note the bypass valve BV1 in Figure 1. It should always be assumed that we wouldn’t be able to send all
the flow from the pool pump through all the extra plumbing we add when we install a solar heater. Adding
the extra solar plumbing can mean we can over work a pool pump unless we’re careful not to try to force
too much flow though too much pipe restriction. The bypass controls how much goes to solar when solar is
on. It's adjustment is explained below under “Start Up”. Controlling solar panel pressure is NOT simply a
matter of adjusting the bypass valve. In fact it has little to do with it. Bypassing some flow only eliminates
the extra pressure caused by sending too much flow thru solar.
If the solar heater is to be manually controlled (saving the cost of the automatic controls) the plumbing
scheme will usually be identical except that the motorized valve will not be motorized. Common 3 way
valves in the pool industry can accept motors as a bolt-on addition later so there’s no harm in starting with a
manually controlled solar heater and automating it later if desired. Manual control is commonly chosen
when the pump can be put on a timer to only operate during the hours of the day when direct sun is on the
solar panels. If the filtering and other pool functions can coincide with that same pump run time then a timer
and manual control allow the system to be operated with minimal inconvenience. You will cool the pool
when running water through the solar panels in the wrong conditions.
The vacuum breaker (VB) is on the pipe going into the collector(s) even if the collector orientation is
sideways. We're trying to have some restriction (head) downstream of the VB so it doesn't open allowing
air in during operation. Air makes noise and the VB will not last 30 years if it is oscillating constantly. The
vacuum breaker prevents negative pressure. If it is sucking air it means the pressure is below zero. If you
are getting air bubbles into the pool when solar is on it probably means you need to increase flow to cause
some restriction to flow thru the solar piping. It also often means its time to backwash or clean the filter.
All the plumbing must slope downhill toward the drains. Simply shut off the pump and wait for most of the
water to drain down to the pool. Note the 3 way valve seals and also the check valves don't let water drain
past them backwards. Open the drains and isolation ball valves and turn the three way valve to let water
past it and wait. Then close the isolation ball valves. Don’t trap water inside the ball valves. Spring start
up is the reverse. Don’t turn the pump on with either of the two isolation ball valves (BV2,BV3) closed
unless BV1 is fully open. The collector tubing is flexible. It can expand as water freezes inside it without a
problem. The manifolds (headers) are rigid. The jargon is sloppy. A manifold is called a header whether
its at the top or bottom (conventional orientation) or left side or right side (sideways orientation). You have
to prevent manifolds from freezing with water in them by draining them manually or by sloping the headers
and attached plumbing downhill back to the pool or a drain point. Leave the drains in the pump area open
in case an isolation ball valve leaks. Close the drains on the roof to make sure water doesn’t get back in. Its
important to understand that water inside a black solar collector will freeze when air temperature on a clear
night is 42F not 32F. This is why it is crucial that solar collectors be flexible. Regular polypropylene solar
panels must be fully drained 100% before night air reaches down to 42F. Good luck with that. You don’t
have to worry about freezing until your piping and solar header manifolds are in danger of freezing solid.
You can blow the solar panels out using a shop vac in reverse. Water can still accumulate at low points.
There is a video at An air compressor won’t do it.
It is very important to check system pressures on a new solar heater especially if we figured the
system pressure was low relative to the roof height and we're using Figure 1a (left). Close the drains,
open the 2 isolation valves (BV2 and BV3 fully and turn the 3-way valve (3w) to direct flow to the solar
panels. Leave the bypass valve (BV1) fully open for now. If it is an automatic solar system and it's not
sunny enough to activate solar then switch the valve manually using the controller. The 3 way valve turns
to send flow to solar but nothing happens at this stage because the bypass valve is fully open so all the flow
goes to the pool and none to solar. The system will fill to some level corresponding to whatever the
pressure is. Not exactly because you’ve created a compressed bubble of air but let’s not get too technical.
Slowly close the bypass valve until the air starts to flush out of the solar panels and into the pool
dramatically. The filter pressure will rise as the air flushes through and then settle back to a new level.
Close BV1 further until you just start to see the pressure gage on the filter start to react. We want as much
flow as possible without adding pressure. You can feel the solar panels when operating in Hot Sun. They
should feel pool temp, not hot, and there shouldn’t be any hot spots. If this is the first time the system is
started up you should install a pressure gauge on the roof at the level of the solar panels roughly (tee in a
pressure gauge on the feed pipe into the solar panels) and check that there isn’t any pressure in the solar
panels when solar is off (but pump on). An easy way is use the threaded hole for the vacuum breaker. Then
turn solar on and verify the pressure is no more than about 2 or 3 psi when solar is operating. Do the checks
and then replace the vacuum breaker right away. Do not purposely add pressure. All you need is less than
1/2 psi to drive more than enough flow through solar. Contact us if there is a pressure situation. We want
to help you correct it now because if we don’t, it spells potential problems later. Watch the pressure spike
as solar turns on and record how much. If it spikes more than 5 psi it's too much. Contact Hot Sun. The
bottom line is DO NOT PRESSURIZE SOLAR PANELS! The lower the pressure on the solar panels
the better. Note: It is important that the solar off pressure is zero. If it isn’t you will have a larger
pressure spike as the system starts up and your solar on pressure will be too high and it will be
difficult to control. See for more on getting that solar off pressure down to
zero. Note that if the vacuum breaker is sucking air, you can increase the flow. Close BV1 further but not
so far that you add pressure.
If the design is a pressure design as in Fig 1b then restrict BV1 to limit the flow to solar. It's possible
but unlikely that with BV1 fully open you will have pressure in the solar panels. The more you close BV1
the more you send flow to the pool through the other leg, the one with the gas heater on it if there is one.
High flow is best for solar because high flow means a colder average collector temp and cold and black is
what we want for best efficiency. However, we can get away with quite a low flow in a pressure regulated
solar design (Fig 1b). If the water trickles out hot after the initial slug of hot water then you need more flow.
If high flow is adding pressure then flow is too high. There is a big range in between.
Note: You probably have a variable speed pump if you live in this century. Luckily there is a big range of
flows that will be compatible with solar but you have to be cognizant of solar pressure. If you crank the
speed up for vacuuming you should check solar pressure in that condition with solar flow on and off. Make
sure all your pump speeds and operating modes don’t overpressure solar and if they do reconsider the speed
settings (because they are probably excessive anyway) and consult with us. You may have to time solar off
with vacuuming or pool cleaning functions. Operating the spa in a pool spa combo using motorized valves
maintaining spa temperature high relative to pool temperature at all times can make for very challenging
solar compatibility. In floor cleaning pop up style automatic cleaners require high pressure and can render
solar designs more challenging. The more you try to do with computer controlled pool automation the more
challenging adding solar can be. Its best to understand the pool operation strategy programmed by the
builder and go over it with Hot Sun in advance of installation.
The fin tubing comes in rolls that are 88 feet long. Each strip is 6 tubes wide and measures 3.75 inches.
Three of these strips go on each 13.5” long header manifold. The headers take up 13.5” when alternating.
The Powerstrip fin tubes take up 11.25” when closely packed in a staggered configuration. We want to
make lengths that don’t leave us with scrap so work with lengths of 1/3 roll (29’4”) or ½ roll (44 feet) or
¼ roll (22 feet) or 1/5 roll (18 feet). These and shorter are your target lengths. Custom lengths like 50’ can
be supplied at a 10% premium. Get us a roof plan. We can help.
Note: We call the manifolds at the top, the top headers and the manifolds at the bottom the bottom headers
rather than calling them headers and footers.
Refer to the specific installation manual addendum for your roof type.
Use the supplied special CA adhesive (CA means cyanoacrylate – Superglue and Krazy Glue are CA
adhesives but they don’t work. They are too thin) to connect the flexible solar tubing to the nipples on the
header pipes. Start by stripping the 4" wide strip of tubing into three tube wide strips so you can glue 3
tubes at a time. Not over the whole length - just strip about a foot.
Simply apply the special adhesive to the nipples all 18 at a time unless its really windy. Fully wet the entire
surface of each nipple all the way around and then slide the tubing on three tubes at a time.. Wear gloves
and be careful you don't glue yourself to the header. Read the warnings on the 4 oz bottle of special
To aid in the assembly it is helpful to build a simple vice to hold the header. This makes it easier and keeps
the special adhesive off your hand so you don’t stick yourself to the header. Hot Sun supplies a kit at no
charge with your system purchase.
Pushing fin-tubing onto header 3 tubes at a time.
Special adhesive
Make sure the entire nipple surface area is fully wetted before sliding the tubing on. A Q-tip (optional) aids
in spreading the special adhesive evenly when using the vice. Alternatively use the supplied smaller bottle
and applicator brush. One dip of this brush fully into the bottle (note the depth it dips is adjustable) is the
right amount of adhesive for all 18 nipples on one header manifold. You can usually wet all 18 nipples and
then push the nipples on 3 at a time. If the special adhesive skins over or dries, reapply. Always wear eye
protection and gloves. Work outdoors and keep your face upwind of the wet adhesive. The fumes are
deadly. Eye protection is very helpful at keeping the fumes off your eyeballs. Push the tubing on 3 tubes at
a time without hesitating because as soon as static contact is made, the bond occurs. Using the vice and
with some experience you can glue and push 6 tubes on at a time. Only apply the special adhesive to the
nipple, not the inside of the fin tubing. The bond is instant when the CA bottle is fresh. Once its been
exposed to air for a minute or two the adhesive is a lot easier to use. An aged bottle off gasses a lot less too
however there is a short shelf life so keep it refrigerated and read the label.
If you do make a mistake and have a leak a great trick is to replace the vacuum breaker with a plug, run
solar, then shut off pump. Air will be drawn into the leak and you can use this to suck pvc cement or the
same special adhesive into the joint. With a minor amount of care its unlikely any of your connections will
leak. See the repair manual.
Normally you’ll attach the header manifolds together and in position along the top or one side first, run the
fin tubing, straighten it out and then use a chalk line to mark the opposite end. Then cut to length and attach
the opposite end’s header manifolds. Don’t assemble all the headers together first and then try to glue the
fin tubes on. That’s a common mistake. Once you glue a pvc coupling to the male end of a manifold its
tough to glue the fin tubing onto that last nipple. Watch the videos.
Alternating means we alternate the direction each header pipe faces using a rubber removable coupling on
the male to male connections and a 2” long stub of 1.5” PVC pipe glued between the female ends.
The headers have a male and a female end. Always use heavy bodied grey pvc cement on all
connections to the headers when attaching them to 1.5” PVC fittings or pipe. Make sure everything is
clean first but don’t use primer. We don’t generally use primer even with 2 part PVC cements (ones that
require the use of primers) because our header material isn’t PVC. Its ASA and ASA reacts with MEK (the
active ingredient in PVC cement and primer) very aggressively. In fact this can be an issue. You don’t want
to seal the header plumbing assembly up with wet pvc cement inside. You want to let it air out for a day
before sealing up the final connections otherwise the MEK can continue to attack the ASA to the point
failures can occur. Follow instructions and heed safety warnings on the cans. Primer if recommended for
the PVC cement being used should be used on all pvc to pvc connections but...its nasty. Its very thin and
can splash in your eyes. It really burns any open cuts and it’s a known carcinogen so yeah it melts the pipe
and makes a better connection but there’s little pressure in this application. We avoid using it for worker
safety reasons. Use a one part cement if you can’t stand to go against a manufacturer’s recommendation.
Don’t use clear cement because you can’t tell if your joint is complete. You’re going to paint it all so there
is no advantage to clear. Join female ends together using lengths of 1.5” pvc pipe. Bevel the cut ends so
they don’t squeegie the pvc cement off. Do not stress this joint for 24 hours. If you make the doubles up at
ground level you have to wait a day before hauling them to the roof unless you’re very careful. Join male
ends together via removable rubber couplings (no cement). The pipe length between female ends can be
varied to space the tubing around obstructions or to line the headers up with rows of tiles or to match the fin
tube position depending on the roof type and configuration you are trying to achieve. Refer to the
appropriate manual addendum for the roof in question. It’s OK to glue pvc fittings to the male ends.
Notice the strap can’t shift off the removable coupling and damage the fin tubing because the gear clamps
contain it.
You can see that when alternating the headers the rubber coupling will sit right against the roof surface. In
the case of a wearable roof surface like regular shingles we have to add a metal plate so the movement of
the headers with temperature doesn’t wear thru the shingle at that point. Use wear plates to protect the roof.
Wear plates are not necessary on tile roofs but on tile roofs think about the movement of the headers as they
change length with temperature. You want to be sure the fin tubes are not contacting the roof near the
header manifolds because the movement back and forth will wear thru the fin tubes and cause a leak.
Staggered headers with pvc pipe
Fin tubing cut before staggered headers attached
Staggered (shown above) means all the headers face the same direction and end up all glued. Staggering
involves two rows of headers eliminating all the spaces between the one foot wide sections. Staggering
allows the 9-5/8” long pieces of pvc pipe spanning between headers to be used to positively secure the
system to the roof while allowing full movement of the header manifolds as they expand and contract with
temperature change. That pipe between adjacent headers is not clamped to the roof. Its inside a short 2”
sleeve of pvc pipe that is clamped to the roof. The “slip collar” elevates the pipe and the manifolds and
allows free movement as the plumbing and headers expand and contract with temperature. Note the manual
addendum specific to your roof type will detail specific mounting methodologies often involving the use of
structural steel members made of P4100 slotted unistrut.
Conventional means the flow of water goes up the roof. Water enters at one bottom corner and exits
diagonally opposite at the top.
Slope exaggerated
Fig. 2: Sloping panel banks and roof piping
In conventional orientation you have to provide a tilt to the top headers so the air doesn’t get trapped. See
the animation under PLUMBING at A corresponding slope on the bottom
headers ensures the bottom headers drain.
Often with conventional orientation the headers will be alternating. The removable rubber coupling
provides a convenient place to hang the solar panel and gravity co-operates.
Note that with Powerstrips it is perfectly acceptable to secure the bottom headers and the top headers. With
other collector types you have to allow the bottom header to float as the entire collector length must be free
to change length with temperature. Not so with flexible Powerstrips. The stress that they pull with when
contracting is far less than with other collector types. This is a huge advantage because this provides a
great deal of wind resistance.
You might choose to stagger the headers if the fin tubes will be relatively long to make better use of
available space.
Sideways orientation means the flow is right to left or left to right. This orientation does not have to be
tilted (like it does with conventional mounting (Fig 2)) because there is no air entrapment potential. The
header manifolds run up the slope and the fin tubes are horizontal. We can do this with Powerstrips
because they are flexible. You don’t have to get the water out of them for freeze tolerance. They can
expand. Generally speaking you want the headers to be on the shorter dimension and the fin tubing to run
the longer roof dimension. This makes for the easiest and most cost effective installation with the fewest
roof penetrations and best aesthetics.
Sideways with alternating headers
Sideways with staggered headers
Notice that with alternating headers you have spaces between the one foot wide sections and with staggered
headers you eliminate all the spaces. Both look good from ground level. They look like they belong there.
Staggering is easier because you don’t have to worry about the stripes between one foot wide sections
remaining even throughout. Staggering allows for some interesting and advantageous roof connections.
Refer to the appropriate manual addendums for your roof type at
In sideways configuration you almost always want to install the fin tubing to the roof first. This is done
with a construction mastic adhesive. Then you run chalk lines and cut fin tubes to length and attach headers.
It is also very important to understand that with a sideways mount you are working against gravity. If the
roof is steeper than 4 in 12 this is going to be a challenging method because the fin tubes will want to slide
down the roof . The connections of the fin tubes to the roof usually via glue strips (described below) have
to be more frequent to avoid sagging. The construction mastic adhesive takes a day to dry. It can be done
on a steep roof. There are ways but its challenging enough that we usually will steer you toward a
conventional mounting approach if the roof is steep.
There are two ways to secure the fin tubing to the roof. We can strap the collectors down using our ppa
(polypropylene A) coated SS (stainless steel) strap and SS hardware (strap clamps and strap brackets) or
we can glue the system down. We can get away with gluing it down because its flexible. The fin tubes don’t
have to shuffle back and forth with temperature as the headers they are attached to change length with
temperature. Strap down is the method used for regular polypropylene collectors out of necessity and it has
major drawbacks such as the large number of roof connections.
Gluing the system to the roof has major advantages and the Powerstrip design affords these advantages.
Construction mastic such as Loctite Powergrab and Lepages Premium bond extremely well to the
Powerstrip material, far better than they do to EPDM synthetic rubber collectors. Because the Powerstrips
can be quite long we want to eliminate the ability of the material to stretch or contract and we do so by
gluing it down. If allowed to float, a 44 foot long Powerstrip could change length by 4 inches. Usually
when gluing a system to the roof we will do so via glue strips. Glue strips are 2 tube wide pieces of
Powerstrip material. The 6 tube wide Powerstrips have perforations along the webs so they can become 2
tube wide strips easily. Start the cut and strip the material apart . We’ll often supply the glue strip
separately but it can be made with raw 6 tube wide material. The logistics behind glue strip vs strap down
would consider that strap down is better if you want to take the system down for hurricanes. Technically we
can meet hurricane codes with either method mostly because we’re properly securing the headers at each
end but meeting hurricane codes doesn’t mean the system survives 100% every hurricane. It means there is
no risk to the public. It won’t come off the roof. It’s a really good idea to take the solar panels down at the
same time as the windows and doors are being boarded up before the town is evacuated.
The strap bracket screws into the roof with a stainless steel screw and polyurethane roof and flashing
sealant. At the ends of the rows of strap use ss strap clamps as shown.
Strap clamps at ends
strap bracket riveted to plate glued
between tiles
Strap brackets every 2-4 feet
Tubing flexes around plumbing vents
Aside from that, most of the advantages are with glue down. On most roof types it means no roof
penetrations except to secure headers. The glue strip also manages the Powerstrips. They don’t get
scattered under a strap over time as they get tossed around by high winds. Glue strips tie each section to its
neighbor meaning the fin tubes remain organized and look neat. Sideways installations are particularly
well suited for glue down because the glue strips are vertical and are needed to prevent the fin tubes from
sagging anyway. If you were to strap down a sideways installation you’d have to use glue strips just to keep
the fin tubing organized.
Glue strips go tube side down so the space between the tubes captures construction mastic. The back side of
the fin tubes glues to the back side of the glue strips with the same construction mastic.
The glue strip can also be screwed with #10 ss screws to the roof via fender washers above and below the
glue strip. This takes the stress off the shingles. Screws can be located to co-incide with rafters for a
structural connection. Seal with black polyurethane roof and flashing sealant.
Loctite Powergrab is most commonly recommended because it is tackier. Its not as runny in warm
conditions. Lepages Premium is recommended on flat installations where the runniness isn’t an issue and in
situations where we are meeting structural engineering approvals for permits or hurricane ratings. Lepages
Premium has a better technical data sheet. Engineers like that
Headers can be angled to match the roof space.
Normally angled headers are used on left side headers, right side headers, bottom headers, but seldom on
top headers. The fin tubes are separated into individual tubes and glued on one at a time. If using a glue
strip , place one parallel to the angled header about one foot from the header. Angled headers are seldom
staggered because you can eliminate the spaces between adjacent Powerstrips without having to stagger
headers. In fact you will usually use glue on couplings male to male ends and space the female ends apart to
match fin tube positions. More on that in the manual addendum. These photos show male end glued to pvc
coupling glued to pvc pipe glued to female end and so on. Many variations are possible.
You can "strip" the tubing so the web of 6 tubes is 6 individual tubes. This can help allow it to twist around
a corner. You don’t want to make roof connections in roof valleys where there is a lot of runoff so being
able to continue the flow through the flexible Powerstrips without stopping can be very advantageous.
For a better esthetic separate the 6 tubes wide strips into 3 tube wide strips before installing the system.
Now you’re only dealing with a 3 tube wide strip. When you separate that out into individual tubes where
you go around corners you can make a cleaner looking bend.
Here are some of the basic “ no roof penetration” schemes we use to support the headers, piping strap on
various roof surfaces.
strap bracket on plate allows header to
be held with ss strap and ss strap clamp
strap bracket riveted onto a plate glued in with
construction mastic
Slip collar allows movement of pipe and no stress transferred to roof connection. Use #40 hose clamp,
strap bracket and sleeve of pipe one size large
via a plate between tiles
Gear clamp holding a strap bracket
to a pipe so it can be strapped positively
In order to flush all the air out it must be allowed to rise to the highest point in the system as shown in the
diagram below.
Figure 13: Typical Multiple Panel Bank Assembly
You can connect male ends together with removable couplings we supply. Do not glue a female header end
to a male end unless you have to. Do not use removable couplings on pvc pipe. PVC can’t take the stress
and the heat combined.
We recommend a slope of at least 1 to 120 (1”in 10’ or 8mm in 1m) for conventionally mounted solar
collectors and piping and that all piping be painted where exposed to sun. Paint the exposed side of the pipe
after installation with gloss black paint, not from a spray can but with a brush and small roller. Slide a
piece of cardboard between the pipe and the roof as you go. Painting is best done before the piping is
attached to the roof but after its plumbed in. Gloss black resists fading better. Black paint allows the
piping to collect solar energy as well. Piping on the side of the house can be painted to match the house.
Keep the pipes next to each other for a neat appearance. We like to use 1.5” because it can deliver enough
flow in most cases without causing pressure and it's so much neater and easier to work with.
You need to be able to drain water from the piping and header pipes at any low points to prevent damage
from freezing (assuming you are in a climate where it does freeze). Slope all the plumbing down to these
Install the vacuum breaker on the free low corner of the bank of solar panels or preferably on the pipe
entering the solar panels. If there is more than one bank of panels the vacuum breaker should be on the
bank of panels that is highest on the roof. Install 1-1/2” PVC end caps on the remaining corner(s)
This is the vacuum breaker. Its just a ½ pound spring check valve. Mount it horizontally so it doesn’t trap
water. It lets air in when the pressure goes below zero ( well… ½ psi) to prevent plumbing from collapsing.
It doesn’t vent air or release pressure. The solar system is open to the pool. Air flushes to the pool upon
start up.
All piping is schedule 40. That’s the thickness. On residential installations the plumbing runs are either 1.5”
or 2” PVC pipe. Horizontal runs of piping along a wall should be supported every 4’ (1.2m) according to
code but this can get hot so we recommend a spacing of 27” for pipe supports especially on the roof.
Underground piping can be buried deep enough that it can stay full of water all winter. Check with a
plumber or city hall for the depth required in your area. Alternatively underground piping can be shallow
and sloped one way or the other to a drain. A drain pit can be constructed where a large hole is dug (about a
foot deeper than the piping), partially filled with gravel and shored up with a box of lumber or even a plastic
pail. If you bury the pipe below the frost level you can get away with drains at ground level where the pipes
come up. There will be a small column of water that will freeze but it can expand up the pipe.
Remember pvc pipe needs to be able to change length with temperature. If you need to secure the piping
very securely for hurricane conditions use a collar. A piece of 2” pvc pipe fits over 1.5” perfectly allowing
the 1.5” to slide freely while the 2” collar down is secured positively. Imagine the piping being long in hot
conditions and shorter by an inch for every 30 feet. Don’t secure a pipe to a wall and then elbow onto the
roof and run 30 feet straight to an elbow into a solar panel. Something has to give when that pipe expands.
Every situation is different.
Its important to understand that unglazed solar panels such as Powerstrips are made of thermo-plastics,
plastics that can withstand high temperature, but plastics cannot withstand high pressures like metals can
when combined with the high temperatures. Stagnating in Hot Sun and no wind, Powerstrips will get very
hot. In making sure your solar system is compatible with your pool mechanical system we are making sure
the system will operate stress free. This means minimizing the pressure on the collectors. Any non-metal
solar collector will fail prematurely if installed under pressure regardless of the pressure capability the
manufacturer claims. The fact is there is a lot of plumbing on the roof and a lot of water flowing and
installing a solar system under pressure is asking for trouble in the long term. Most pool/roof combinations
are suitable for a problem free solar heater and your Powerstrip dealer will always check first to make sure
(in an ideal world) . Start up instructions at the start of this manual tell you to check the pressure in the
collectors with a pressure gauge.
Air Bubbles:
You should see a big flush of air when the solar heater starts up in the morning. It should stop after a few
minutes. If air is entering the pool inlets constantly after the system has started up then the vacuum breaker
is probably opening and allowing air to enter. Go on the roof and listen to it. You will hear air entering the
vacuum breaker if it is the source of the air. If it isn't, then you have a leak on the pool plumbing before the
pump or near the top of the solar panels. Check the pump lid seal. The vacuum breaker is mounted to the
bottom header of the bank of solar panels to try and keep some pressure on it so it stays closed. One
remedy is to just live with some air bubbles. Another remedy is to have the pump serviced to increase the
flow though the solar heater. Perhaps the filter just needs to be cleaned or backwashed. Yes, that's right.
Your filter needs to be cleaned. That's why the vacuum breaker started sucking air. You can increase the
flow thru the collectors if BV1 isn’t closed all the way already. Close it until you see the pressure gage on
the filter react. Closing BV1 to send more flow to solar is the same effect as increasing the pump speed but
we try to avoid having to do anything different for solar. Your pump speed is set for filtering and unless it
is set pointlessly too low you shouldn’t have to change it to accommodate solar.
Poor performance:
If you suspect the system is not heating as well as it should be, check the solar panels on a sunny day.
When operating (water flowing through them) solar panels will be cool to the touch across their entire
width. Near the bottom of the collector (or feed side) the collector will be close to the swimming pool
temperature. Near the top of the collector the temperature will be a little higher (depends on flow rate) but
for efficient operation will only be about 5-10 degrees F higher than pool temperature at solar noon. If
there is a hot spot, then water is not flowing through this area. Make sure the panels are draining down
some when solar shuts down to ensure you aren’t losing heat at night.. Without turning the pump off, turn
solar off, wait, then on again and make sure you see air bubbles flushing into the pool. This confirms the
panels drained down when off. If they don’t drain down you could be losing heat if the pump is on at night
due to an induced backwards cooling circulation.
The sizing charts for cities around the US found under sizing on are a good reference
point when evaluating solar performance. If your system isn’t doing what our performance charts indicate
then we want to know about it and we’ll figure out what’s wrong with your system or our predictions.
Remember, you don’t need a bigger pump. Don’t let your trusted pool technician tell you that solar takes
extra pumping power. Keep the pump spec. under control and solar will not have to operate under pressure.
Pressure is stress and why have stress if you don’t need it? Know how to tell your solar system is not under
pressure and remember forever that it does matter if your filter or pump are ever changed or “upgraded”.
Hot Sun is married to your pool mechanical system forever now so consult with us on changes in the future
please. [email protected]
SERVICE: You can splice the tubing with ¼” pvc drip irrigation – see repair manual. Beware of
polypropylene drip irrigation tubing. Make sure its pvc aka vinyl. You can always test it by seeing if it glues
to itself with the CA adhesive. PVC cement bonds to the collector material as well as the headers. So does
Krazy Glue or superglue. Use the gel versions of these products not the extra runny regular versions. Best
is Gorilla brand superglue- see repair manual (under manuals at If you have a leak, seal
the vacuum breaker location with a plug, run solar, then shut off the pump. Air will be drawn in at the leak
location. You can use this to get pvc cement to flow into the joint.
Auto Controls: If its not coming on or off automatically as it should check the sensors. The two sensors
(one on the roof and one in the pool plumbing) are 10,000 ohm thermistors. They measure 10,000 ohms at
room temperature. Lower when hotter, Higher when colder. If solar isn’t coming on when it should, short
out the roof sensor at the control panel . If that makes solar turn on then it’s a broken wire to the roof
sensor or a bad roof sensor. If that doesn’t work disconnect the pool temp sensor. If solar comes on then it’s
the pool temp sensor. There is a small toggle switch on the motorized valve. Make sure the pool service
guy didn’t switch that to the center position so the valve won’t turn or to the opposite position so the valve
turns the opposite way it should. . Parts for these control systems are universal and available worldwide.
The motorized valves are pool industry standard parts.
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