How Swimming Pool Valves Work
With so many people moving to Florida and owning their first pool, it’s not surprising that a majority of pool owners are baffled by their swimming pool plumbing system. When we endeavor to add solar pool heating, the plumbing at the pool equipment pad becomes a bit more complex, but it’s not too hard to understand your plumbing and valves once you understand which way the water flows through each pipe. In this article we attempt to explain the basics of how pool valves work with solar pool heating, and what all of the plumbing does.
When you have a solar pool heater, valves can be broken down into three groups.
- Pool Suction Valves – these valves control pipes that suck water out of your pool.
- Solar Valve Manifold – these valves divert water to solar panels, or stop water from entering solar panels.
- Pool Return Valves – these valves control through which jets and features water is returned to the pool.
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Diagrams of Pool Valves with Solar Pool Heating
- Suction Valves
The suction valves control from where water comes into your pump. You can tell which valves are the suction valves because they enter the pump horizontally. The vertical pipe out of the pump is for water coming out of the pump — the discharge side of the pump. Typical suction valves include main drain(s), skimmer(s), suction cleaner(s) (vacuums), and spa suction for pool/spa combinations. These are all of the places that water can be drawn out of your pool.
- Pool Pump
Your pool pump circulates water through the filter, solar panels, auxiliary heater, and chlorination system (not pictured). The pump can be a single speed, two-speed, or variable speed pump model, and it is sized to provide adequate water circulation and filtration for your pool and pool features.
- Pool Filter
The pool filter takes physical contaminants out of your pool. This may be a cartridge filter (most common), sand filter, or diatomaceous earth filter.
- Solar Valve Manifold
4a. Filter Check Valve
4b. Solar Diverter Valve (aka 3-way valve, bypass valve, solar valve)
4c. Solar Isolation Valve
4d. Solar Return Check Valve
Every well designed solar pool heating system should include four valves for proper directional control, diversion, and isolation.
The first check valve, which allows water to flow only one direction) prevents water from back washing the filter into your pool. When the pump turns off, water drops from the roof mounted solar collectors, and if this check valve was not present, debris in your filter would go back to your pool through the suction plumbing.
The solar diverter valve controls whether water goes up to the solar panels or goes back to the pool without entering the solar panels. There is (should be) a tiny hole in this valve that allows water to drain back to the pool when the pump shuts off. The water drains through the hole and back to the pool through the return plumbing This hold is small enough that only a small amount of water can pass through it when the valve is in the closed position.
The solar isolation valve prevents any water from entering the solar panels. This is important for service purposes and to positively isolate your emptied solar panels when not in use for extended periods of time. Remember that the solar diverter valve has a small hole in it, so without this valve there would be no way to prevent all water from entering the solar panels.
The return check valve allows water to only come down from the roof in this plumbing line. This stops water from going up the return line when the solar diverter valve is in the off position and your solar pool heater is not operating.
Note that this valve manifold may be flipped left to right with the solar diverter valve on the right side depending on the location of the solar panels relative to the pool equipment.
- Auxiliary Heater (optional)
Your pool may already have a gas heater or electric heat pump pool heater before you install your solar energy system, or an auxiliary heater may be installed to supplement solar heating depending on your particular circumstance. The auxiliary heater is completely optional with solar pool heaters, but most people with a spa want a traditional heater to quickly heat a spa on demand.
- Pool Return Valves
These valves control where water is returned the the pool. The valves can turn on and off the side jets, fountains, waterfalls, bubblers, therapy jets, spa spillovers, and other pool water features.
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Your pool may have a different plumbing and valve configuration, and pools with lots of features can be quite complicated. Pools with attached spas will also have additional 3-way valves to control the spa operation (see below). Some pools only have a single suction and/or single return line, and some suction and return lines may not have valves on them at all. Also, some suction and return valve manifolds may use 3-way valves to reduce the number of valves required and provide extra functionality in selecting a water source or feature return. Valves can also be used to control the flow through features, like the height of a fountain.
In the above diagram, there is a 3-way valve on the suction side and the return side that controls spa operation. When the spa is being used, the typical desired configuration is to isolate the spa so the pump only draws water from the spa and returns all of that water to the spa only without a spillover. That way you can heat the spa independently from the pool and maximize the flow rate through the spa jets. In the valve configuration above the pool is in normal operating mode, drawing water from the pool only and returning water to both the spa and another pool jet or feature. This way the pool owner can circulate the spa and pool simultaneously and have a nice spa spillover effect.
Pool plumbing systems are as diverse as the pool builders who build them. You will see all kinds of different valve and plumbing configuration based on the budget, installer skill, philosophy, components, and overall system design. Even solar pool heating manifolds differ. For example, some installers prefer the diverter valve on the return line.
We have explained pool valves with solar pool heating systems. If you have questions specific to your pool equipment, post your comments below and we will do our best to help you!
Jason,
A couple of questions. I had a solar system installed that utilizes a Hayward Gold Line GVA-24 Valve Actuator. When the system was installed, the installer indicated the Actuator was to be set at the ON1 position. On this position, the handle is on the left side of the unit. The “to the pool PVC” pipe has a small section with clear plastic and a white flapper inside. When the Actuator is set at the ON1 position, you can’t tell if there is water flowing thru the clear section. No bubbles nor any movement from the flapper. If you move the Actuator to ON2, water rushes thru like gang busters. Flapper is totally raised and you can see the water in the pipe. Also the handle is on the right side of the unit. When the pump is shut down you can see the flapper close. Why on one setting and not the other? Is this normal? I opened my pool on Tuesday. Yesterday, due to so much debris, I had to backwash my DE filter several times. I noticed the handle to the Actuator was now on the right side, where it is located in the ON2 position. Why?What would cause this since the setting was still in the ON1 position. I’m a new pool owner and all this is Greek to me. The temperature here in NJ is still in the 60s so I don’t expect the pool to jump up to 90 degrees but because of what happened I want to know if everything will start working once the weather warms up. Thank you for the info.
Brian,
If your installer told you to leave it in the ON1 position, leave it there. The controller will command the actuator to turn to the proper position when solar is available (roof temp is higher than pool temp) and heating is needed (your desired set point is above the pool temperature).
If you move it to ON2, it will work in reverse. It will cool your pool down. It will run water through the panels when there isn’t enough sun. It will not run water through the panels when it should.
The ON1 or ON2 position for a given pool situation depends on the orientation of the valve when it was installed. Each individual pool has a right and a wrong setting.
Jason
Hello , I am having my pool solar removed without reinstallation. one company suggested I remove all of the solar pool parts and valves from the pump area and the piping to and from the wall of the house to prevent future leaks. One company suggested that I remove the piping from the roof but keep the solar pool parts and valves by the pump since I am planning on selling the house-this would be useful to potential buyers who wish to install a new solar system. What are your thoughts? I would greatly appreciate your input.
Hi Marva,
I would remove everything. An installer is likely going to insist that they replace it anyway to meet their standards – at least a good one will.
Jason
I have an inground pool with 2″ plumbing running on a Pentair VS pool pump. I just purchased some solar panels, but they only have 1 1/2″ headers. Is it reasonable to use a 2″ diverter valve to the 1 1/2″ panel plumbing, but not open the valve 100% so that some of the water is able to bypass the panels as a means of reducing the pressure created by the 1 1/2″ panels? Or, do you have another suggestion?
Hi Bob,
You have that backward. You will need to increase the pressure to improve the flow rate. That is the problem with 1-1/2″ plumbing and panels. It takes more energy to push the same amount of water through them. If you have a single-speed pump, you will have higher pressure and less flow, which is not ideal. Lowering the pressure just reduces the flow even more, causing less heat transfer.
Jason
Thanks Jason. I decided to return the panels while I still could and will look for panels with 2″ headers to hopefully “do it right”.
Roof solar pool question. Everyday, when my solar diverter valve turns and shuts off water to roof (pump is NOT running at that moment), I hear a fairly large noise that appears to be coming from the solar diverter assembly. The diverter swivels entirely to the closed position…the noise then lasts about 20 minutes or so then stops entirely. I took the upper housing off pentair diverter and gears, limit switches all functioning ok. Will pull out entire diverter assembly tomorrow. But is the noise I hear possibly water coming down from roof leaking through a worn check valve causing vibration or perhaps the pentair diverter seal itself allowing water to drain backwards? Vibration sound is definitely coming from diverter housing.
Hi Keith,
You probably have a Pentair brand diverter valve with integrated check valve. The gate of the valve allows water to drain down when the pump is off, but doesn’t allow water to go up to the roof when the valve is in the solar bypass position. These little internal check valves are know to cause loud buzzing when they malfunction like you suggest.
You can drill a tiny hole in the check valve or adjacent to it to alleviate this issue, up to 3/16 inch. The small hole will not allow enough water up to the roof in the bypass position to matter. This should stop the buzzing.
Alternatively, you will need to replace the valve internals if you can find a kit or buy a new valve and swap out the internals.
Jason
Just had 2 pvc solar pipe sections replaced due to damage. Solar system worked for 2 days but this morning when I turned pool pump on no water flowed thru pump. Gauge needle did not move and when I opened air seal at top of pump, no air or water escaped like it normally would therefore confirming no water in pump. Filter basket next to pump has water, impeller is clean and movable, but no water flow whatsoever. No water moving in skimmer area. Is this just a valve thing? HELP!
Hi Julie,
Your question is a bit ambiguous and hard to diagnose unless on site. It sounds like your pump could be “dead-headed,” meaning there is nowhere for water to go because a valve is closed somewhere. That is a very bad situation and you should not run your pump until you resolve the issue. If the pump basket has water in it, it does not sounds like a suction/priming issue, so that points me to the pressure side of the pump. Get a pro to look at it to avoid damaging your pump.
Jason
Hello Jason,
Is your solar manifold designed only for Florida climate? I ask because I’m installing in MD where we have to winterize and drain down our pool systems. Check valve 4a would appear to trap water between itself and the solar diverter valve. How would this section of pipe drain?
Thankjs
Charles,
The solar bypass valve contains a drain down hole in the gate or an integrated check valve that allows for drain down through the pool return plumbing. The drain down water does not return to the pool via the suction plumbing.
Jason
I am not sure whether the switch on the bottom of the control valve is in the closed position or not. If the switch is set all the way to the back is it off ?
Hi Nick,
It sounds like you need to watch our video covering the actuator toggle switch position.
/solar-pool-heating-valve-actuator-toggle-switch-position/
That should answer your question.
Jason
Hi Jason.
I have a pool in CA. Palm Springs.
The Solar heating is programmed for 9-5 and 85 degrees. The filter pump is also programmed to run from 7a to 7p. However, in the hot months the pool temp is well above the set temp. so the solar heating shuts down. The side effect is that the filter pump shuts down too… As a result the pool does not get enough circulation…
Is this normal? From what I read here, one of valves should be diverting the water to the pool and bypass the panels.
this is a ‘new’ system. I just want to know if this is normal, so I can ask the installers to make the corrections.
thanks
Hi Oz,
No, that is no normal. There is no such thing as a schedule for solar on any major controller I am aware of. You just set the desired temperature and the desired heat source. If there is a schedule, it should not be there. I don’t know what type of controller or pump you have, but that is not normal function at all.
What you could be describing is one pump type that shuts down when an external control signal is lost. This is a poor choice of a pump/controller combination, but there are ways to bypass this deficiency. It usually involves using a mechanical timer for the filtration timing function rather than the onboard timer. In this case you have to jumper the controls to force the pump to run at the filtration speed whenever it has power. This is less than optional, but the only way really to ensure proper function.
It sounds like you ned to have your installer back out. Honestly, I don’t know many people that can figure this out when you hav ea suboptimal controller pump/controller pairing. Frankly, when we run into it we strongly encourage clients to upgrade to something better for the best experience.
Let me know what you have and if I can assist further.
Jason
P.S. I’m trying to remember when this occurs exactly, but it sounds like you might have a JEP-R pump controller and a Jandy Pump. This combination doesn’t work well with third-party automation controls because the remote signal logic is flawed. It allows the pump speed to be changed by external controls, but ignores schedules when external control is reliquished.
Turns out the “problem” was an interaction of features in in the iAqualink system. That system has a complex menu of options. Some options can be selected in the schedule menu. BUT, there are several other options for scheduling. For example, it is possible to select the pool or spa light to turn on at dusk. That choice is NOT visible on teh schedule options.
In my case, there was another option to “keep temp” constant from 1am to 11PM (all day). The way this function works is to turn the filer pump on for 5m every 2 hours, test the pool temp and then make a decision if the heating needs to turn ON. That function overrides the filer pump function. But unless one knows to look for it, you would not know it is there.
Once that option was turned OFF, the filer pump functions as expected in conjunction with the solar heating.
Thank you for accepting questions. I’ve a rooftop solar heating system for my in-ground pool; it appears to be working correctly (no leaks, heats the water, etc.). I’m unsure of its age but I suspect it maybe 10 or more years old. While cleaning gutters, I discovered a brass spring-loaded valve that was removed/replaced with a plastic plug by local “handymen” (Dumb and Dumber) that serviced the property before I moved in. The valve was located at the end of a collector pipe that provides heated water to the pool. Do you have any idea what this valve is for and how critical is it to the system’s function? I’m concerned that pressure and vacuum could result in problems, long term. Any information is appreciated. Many thanks.
Hi Dave,
The short answer is that it sounds like you are missing a vacuum relief valve. For a detailed description of why it is important, go here: /vacuum-relief-valve-for-solar-pool-heaters/
Hello! I’m not a customer but I have a solar heated pool. I moved into a house with it so I’m unfamiliar with the pipe system being used. When the solar system is in “AUTO”, the automatic valve actuator switches from regular outlet pathway to “to solar” pathway. The solar panels are on my back fence wall so the pipe goes underground. At the pool system, the “to solar” pipe goes underground and right next to it is a pipe with a feed line check valve or Return Check Valve(window to see water passing through) and the arrow on it points up to the sky. It connects to the regular pathway I mentioned earlier. Now this pipe has a 3-way valve that comes after the window check valve (the 3rd way is labeled “Therapies”??). Then continues with 3 thin pipes connected to it (labeled “Quik Skim”, “Aerator”, “Dek-Clor”) before it ends at the Pentair Intellichlor and goes underground. There’s also a pump motor connected to a pipe that goes underground labeled “Water Feature” which I’m assuming is the water slide. There’s also a random pipe that sticks out if the ground with a cap on it that’s labeled “Therapy Air”. I think the problem is that I’m not seeing any water in, what I’m guessing is, the Solar Return Check Valve. I’m supposed to see water here, right? That means the water is coming back from the solar panels into the pool? Thanks for your time and help!
It’s hard to tell without looking at your system because many pools are plumbed differently. Are you sure the return check valve does not have water in it? You can’t “see” water – it’s clear. If it’s a spring check valve with a flap, you can see the flap opened when it has water in it. Many people make the mistake of thinking there is no water in the valve when in fact it is full of water.
It just keeps getting worse. The heat pump inline with the solar return and no way to bypass it just introduces even more back pressure. Depending on the heat pump, it may have significant flow resistance.
A lot of pool buyers and pool builders are now regretting pop up cleaners.
It’s just a bad situation that the solar dealer should have recognized and addressed up front. You could use the Florida solar rights statute to convince your HOA that their restriction impedes the ability for you to have solar and increases the cost substantially. Replace everything with white PVC, increase all plumbing aboveground to 2 inches, and use panels with low back pressure (like the iSwim we offer). Bypass the heat pump. But you still might have issues with ballooning rubber couplings. If properly installed they should not leak.
It’s a tough situation. Frankly, I would recommend a different approach – an efficient heat pump and enough solar electric panels to offset the utility electricity cost. Your system is not well suited to solar pool heating panels.
I doubt you will be able to economically and permanently fix your frustrations.
Yes, I do have a check valve on my return line. I also have one after the filter and now there’s a check valve built in on the three way solar valve. I also forgot to mention that I have two Vacuum Relief (VR) Valves. One in between both set of panels and another one at the end of the return line (closest to the return check valve). I also have a shut off valve (ball valve) above the three way where I can isolate water from going up to the solars/roof.
The return from the solar actually goes into my heat pump (which I use for my spa during the off season).
The problem that I see is that my pop up heads are my only returns in the pool (I don’t have dedicated standalone returns in my pool). I also have pop ups in my spa as one of the zones and the only other returns I have are two in my spa (which creates the spillover). So if I turn my pop up heads off (essentially turning the valve off), my only return would be in the spa via its two returns. So spreading the water flow would be poor (both in chemicals and heat spread). I guess it’s an option, but one that defeats the purpose I suppose.
The previous owners built the pool around 2008. Not sure if 12 years is considered “old” in terms of technology, but I agree that the pop ups don’t really do its job. I didn’t build it, so I’m stuck with them.
Any other recommendations based on the additional information I provided? Thanks.
Joey, I have bad news for you. Pop up cleaners are a nightmare for solar pool heaters. The extremely high back pressure means that flow through the panels is very low, increasing temperature. This is a bad combination for plumbing, especially black plumbing. High temperature and high pressure is bad.
Second potential issue: if you don’t have a check valve on the return line from the solar, you are going to seriously stress the plumbing and panels. Many (most) dealers don’t install a check valve, which I consider a requirement.
Your best option is to bypass your pool cleaner popups (if possible). Abandon them.
Pop up cleaners are pretty old school. They don’t work well and they are energy hogs (more pressure means more horsepower or more pump run time to achieve turnover). It sounds like your pool is older. You probably also have 1.5 inch plumbjng. Everything is working against you. High back pressure is a challenging problem.
It’s unfortunate that you are not in my service territory, but there might not be much I could do to help. It’s truly a tough issue to resolve. You need to increase the flow and reduce the pressure in your solar panels and avoid high pressure stagnation.
Bibs as in the black rubber fittings that connect the solar panels to each other.
Yes, I have black pvc, per HOA and because the panels are black. The new modifications were recommended by the manufacture of the panels. The frustrating part is my neighbor across the street has the same system done by the same company and they have no issues. Every three weeks or less I have a new leak. Only difference is my pool is bigger, I have more panels, and I have the cleaning pop-up heads that also act as my returns for the pool.
Maybe boiling is exaggerating a bit on my part, but the water is very hot when I go to the leak on the roof. I can’t keep my finger over the hole for more than a second or two.
The manufacture recommended the three way valve with built in check valve, instead of the hole, because I have very long run of pipes and panels and they are all on the first floor (and we need assistance to drain back down to avoid the water stagnation). It’s working fine when it shuts off, but not when the water reaches the temp and the solar turns off, but the pump still running.
I’ll bring up going back to the old method of the three way valve, but maybe with a bigger hole. We’ll see what else we need to do.
Thanks again
Hi – very helpful site. You did not install my system (I’m in Florida, but north of your region). I have an issue with water staying up in the panels when the solar valve automatically shuts off (temp is reached), but the pump is still running. This is causing the water to over heat and making my rubber bibs / fittings to burst causing leaks. When I go on the roof this water is really hot. We recently had a solar company change the three way valve by installing one with a check valve (instead of just a hole).
Now when the pump turns off I get complete drain from the solar panels. This new valve also prevents water from still going up when the solar turns off, but the pump still running (compared to my old one that had a small hole and still allowed water to go up when the solar is off). However, I still have the same issue as before when the the solar turns on early in the day and then turns off when the temp is reached within an hour (88 degrees). In most cases my pump is still running for another 5 to 6 hours preventing water from draining back and causing this boiling effect.
How do we get water to drain back down even when the pump is still running? We’ve had numerous pvc fittings and bibs give out since installation. We have a Hayward singe speed pump and filter that runs at about 32 PSI. My automation systems is a Jandy, but have an automated Hayward actuator for the three way solar valve. We have two sets of panel (5 each and are 12 feet long each, for a total of 10 panels). My pool is about 19,000 gallons and both sets of panels are on the first floor.
This is getting very frustrating and would appreciate any help, advice, and recommendations on what to do next. The solar company is still investigating as well.
Thanks!
Hi Joey,
First, I’m not sure exactly what you mean by “bibs.” But I’ll answer your question anyway. A solar pool heating system is typically designed to handle the temperature of stagnated water that is in the system under the conditions you mentioned. I’m guessing you have black PVC plumbing on the roof. Black PVC fittings and pipe are not a great idea because they are not as resistant to heat as white schedule 40 PVC. Black fittings can split where they are molded together as the PVC pipe swells.
It sounds like you are trying to drain the panels when the pump is running. That isn’t going to happen. It’s impossible without having a completely separate plumbing drain line going back to your pool, which pools are not built with. The solution is actually the opposite of what you are attempting to do. What you want is a larger hole. You should allow a small amount of water to flow through the system when the temperature is reached and solar is off. This small amount of water will not heat your pool much but will keep the water in the panels circulating.
But ultimately, the system should be designed to handle the stagnation temperature of water trapped in the panels. It will not “boil” as the stagnation temperature is well below 212ºF.
And if I’m right and you have black PVC, consider replacing it. We only install it when HOAs require it and customers absolutely demand it. It’s a terrible idea. I keep telling people, but nobody wants to listen.
How do I stop water from flowing to the solar heater? One of the pipes on the roof has developed a leak.
Hi Debbie,
Based on your name and email address I don’t believe you are one of our clients. Our competitors routinely do not install proper isolation valves, so it may not be possible to stop water from reaching the roof, especially up the return line from the solar panels. We install a solar bypass valve and an isolation valve on the feed line. The return line has a check valve that prevents water from reaching the panels in reverse. Unfortunately, I have to advise you to turn your pump off and contact a solar professional or pool service in your area. If you are in Southwest Florida, call us at (239) 491-8010 and we can help.
I just had a Hayward salt chlorinator installed and now there is water going to my solar panels when the valve is off. Prior to install it never happened and the pump was running at a higher speed. I know this because I have a small leak in panels so I’ve had it off waiting for repair. Wake up the first morning of install and find water running off my roof. Why would installing a new chlorinator force water past closed valve? Very perplexing! Thanks for your help.
Hi Mr. B,
That’s hard to say without looking at it, but it sounds like either your installer removed a check valve on the return line from the solar or left a valve in the wrong position. I will email you and you can send me a picture of your equipment.
Hi, in my solar pool heater setup, there’s a thin tube (about half inch diameter) about half way up the wall that connects the return pipe (the ones bringing the hot water from the roof) with the supply pipe (the one taking the water up to the solar panels). Any idea what function this connector serves? the tube is connected at each end (of the PVC pipes through a small plastic connector (a tube with a cylindrical tab in the middle). One of these connectors is broken. Any idea where I can get a replacement one?
You have an old school drain down bypass. This allows the system to drain when the pump turns off. We now install valve manifolds with either check valves or holes in the bypass valve to fulfill the same function. I have no idea what connector you have, but any plumbing replacement that fulfills the same function will work, or abandon it and drill a 3/16″ hole in the gate or ball of your solar bypass valve.
which way should water flow in a pool when there is a solar heating system?
East to West?
West to East?
From floor to Up?
From Up to floor?
(Its a question on my exam that i did not understand)
Hi Matt – I honestly have no idea what that means. Was that the actual question on a test?
if I want to truly isolate water flow to/from my solar panels should I have 1 valve for water to panels and 1 valve leaving panels?
You can use an isolation valve on the feed line and a check valve on the return.
Installing an isolation valve on the turn can cause your system to be “dead headed” if the wrong valve is closed, causing excessive pressure and pump or panel failure.