What PoolBoss Says
Pool valves do three jobs on an equipment pad. They pick where the pump pulls water from, pick where it sends water, and stop flow so you can work. Trace the suction side first, then the pressure side. Turn the pump off before you move a handle, and never run it against a closed valve.
Six handles, no labels, and pipe running every direction. You've never worked this pad, and the last company left nothing behind. One wrong turn and the pump has no water, or the heater quits, or the spa drains into the pool.
Swimming pool valves only come in a few kinds. Once you know them, any pad reads the same way. Below is what each valve does, how to read a three way valve without guessing, the six multiport valve positions, and the two moves that break equipment. Then how to tell a valve you can fix from one that needs a quote.
At a glance
Key takeaways
- Turn the pump off before you move any valve handle.
- On a Jandy-style diverter valve, the port under the word OFF is the closed one.
- Check every valve between the pump and the heater before you quote a heater.
- Photograph the pad on your first visit and save the normal valve settings on the pool's record.
What do the valves on a pool equipment pad do?
Every valve on the pad does one of three jobs. It picks where the pump pulls water from. It picks where the pump sends water. Or it stops flow so you can open something up.
The pump splits the pad in two. Everything between the pool and the pump is the suction side. Everything after the pump is the pressure side. A valve on the suction side picks between the skimmer, the main drain, and the spa. A valve on the pressure side picks between the pool returns, the spa, or a water feature.
A two way valve has two ports. It opens or shuts one line. A three way valve has three ports. It sends water one way, the other way, or some to both. A three way valve is also called a diverter valve. The Jandy valve is one common style, with a handle on top and a lock knob on the handle.
The table lists the pool valves you'll meet on a home pad and what goes wrong at each one.
| Valve | Where it sits | What it does | What goes wrong |
|---|---|---|---|
| Two way valve | On any single line | Opens or shuts that one line | Shut on the suction side with the pump on, the pump gets no water |
| Three way valve on suction | Before the pump | Picks skimmer, main drain, or spa | Set wrong, the pump pulls from the wrong place or gets no water |
| Three way valve on the return | After the filter and heater | Picks pool, spa, or a water feature | Left part way, water goes where you don't want it |
| Multiport valve | On a sand or DE filter | Filter, backwash, rinse, waste, recirculate, closed | Turned with the pump on, the valve can be damaged |
| Check valve | After the heater, before a chemical feeder | Lets water move one way only | Stuck open, strong chlorine can siphon back into the heater |
| Heater bypass valve | Across the heater | Sends extra flow around the heater | Moved, the heater gets too much flow or too little |
| Air bleeder | On top of the filter or multiport | Lets trapped air out | Left shut at startup, air stays in the tank |
Read the word OFF, not the handle
It's easy to read a diverter valve by which way the handle points. We think that gets pools set wrong. Read the word OFF.
On the common Jandy valve, the handle has an OFF mark. The maker's install sheet says that mark shows where the seal inside the valve sits. So the port under OFF is the blocked one. The other ports are open.
Point OFF at a port and that line is shut. Turn OFF away from a port and that port opens. Set it part way over a port and that line gets part of the flow. Stops on the cover catch the handle when a port is shut all the way, so you can feel it.
Two more things are on that cover. The word INLET goes over the port the water comes in from. And the knob on the handle is a lock. Loosen it to turn the handle, then snug it finger tight. A handle that won't move may only be locked.
Other brands mark their handles their own way. If you can't find a mark you trust, don't guess. Turn the pump off, move the handle, turn the pump on, and watch where the water goes.
Trace the suction side first, then the pressure side
Start at the pump and walk the pipe both ways before you touch a handle.
Go backward from the pump first. Those pipes run to the pool. Find the valve that picks between the skimmer, the main drain, and the spa. That's your suction side.
Then go forward. On a standard pad, the pump pushes water to the filter, the filter sends it to the heater, and the heater sends it back to the pool or spa. A chemical feeder goes after the heater, with a check valve between the two. The check valve keeps strong chlorine from siphoning back into the heater when the pump is off.
Now you know what every handle does. Take one photo of the whole pad with the valves where you found them. Write down which handle is which and where each one sits for normal running.
Put that where the next tech will see it. In PoolBoss, each pool keeps a list of its equipment, and each record holds notes and a photo. Add the pad's valves as a record under Other, with the photo and the normal settings in the notes. With keeping equipment notes and history on each pool, the tech covering your route reads the pad on his phone before he touches it.
Mark the pipes too if the customer is fine with it. A paint pen on the pipe helps whoever stands there next.
The six multiport valve positions
A multiport valve sits on a sand or DE filter. One maker's guide for a six-way valve lists six working positions, and the table shows where the water goes in each.
Two rules come from that guide. Turn the pump off before you change positions. And never run the pump with the valve on closed. The guide warns that the equipment can be badly damaged and that parts can come apart.
That valve tops out at 50 psi. The filter tank has its own top pressure on its nameplate. Stay under the lower of the two.
The same valve has an air bleeder. Open it and stand clear before you start the pump. Leave it open until a steady stream of water comes out.
This post doesn't walk through a backwash. For the steps, see backwashing through the multiport.
| Position | Where the water goes | Use it for |
|---|---|---|
| Filter | From the pump, through the filter, out the return | Normal running and vacuuming through the filter |
| Backwash | From the pump, backward through the filter, out the waste line | Cleaning the filter |
| Rinse | From the pump, through the filter, out the waste line | Settling the filter bed after a backwash |
| Waste | From the pump to the waste line, around the filter | Vacuuming to waste or lowering the water level |
| Recirculate | From the pump to the return, around the filter | Moving water without filtering it |
| Closed | Nowhere | Never with the pump on |
A half-open valve can shut a heater down
A gas heater won't fire without enough water moving through it. A valve left part way closed can drop the flow under what the heater needs.
One maker's guide gives the least flow for each heater size, in gallons a minute (GPM). Its 175 and 200 models need 20 GPM. The 250 needs 25 GPM, the 300 needs 30 GPM, and the 400 needs 40 GPM. Every size tops out at 120 GPM.
That heater has a water pressure switch. When flow is restricted, the guide says the switch may keep the burner from firing and turn on the Service System light. The display can show ERR PS, which means the switch is open.
Hypothetical example: you take over a pool with a 400 size heater that won't stay lit. The customer has been told it needs replacing. You trace the pad and find a three way valve parked half way, sending part of the water around the heater. Set it back, and the heater may get the 40 GPM it needs.
So check every valve between the pump and the heater before you quote a heater. Check the filter and the pump basket too. The same guide says a suction line plugged with leaves can starve the heater.
Two more things from that guide. The pipe leaving the heater shouldn't have a shut-off valve on it. And when a pump can push more than 120 GPM, the heater gets a manual bypass valve. Once that valve is set, the handle comes off or gets locked. If you find a bypass with no handle, somebody set it on purpose. Leave it alone.
Stop at the valves. Gas and electrical work inside the heater goes to a licensed tech.
Two moves that break equipment
Both of these happen with the pump running.
The first is cutting off the pump's water. Close a suction side valve while the pump runs and the pump has nothing to move. Close everything on the pressure side and the water has nowhere to go. One valve maker's guide says running the system with no flow will seriously damage the equipment.
The second is turning a multiport handle with the pump on. The same guide says to always turn the pump off first, to prevent damage and injury.
So make it a habit. Pump off, move the handle, pump on, watch. If the pump runs on a timer, make sure it can't start while your hand is on the valve.
If the pump won't catch water after you've moved a valve, put the valves back where your photo shows them. If it still won't, work through a pump that won't hold prime.
When a valve turns into a quote
A valve that's hard to turn may still be a good valve. Check the lock knob first. Then look for the four signs below.
Put the valve on the quote by name, with a photo. In PoolBoss, a quote or job can name the piece of equipment it's for, so the customer sees what you're replacing and why.
Cutting in a new valve is plumbing work. The Jandy install sheet says the valve has to be installed and serviced by a contractor who is licensed where the state or city requires it. Check your own state's rules before you glue pipe.
Add the valves to the equipment check at every visit. Look at each handle for drips while you're there.
- Water at the handle. On the multiport in that guide, a leak at the handle is a worn o-ring, and the fix is a new valve top.
- Water out the waste line while the filter runs. The guide lists dirt or sand under the seal, a damaged seal, or a damaged valve body.
- A cracked port. The guide's fix is a new valve body, and it warns you not to overtighten the fittings.
- A cracked diverter valve housing. On that Jandy valve, the housing isn't sold as a separate part, so a cracked one means a whole new valve.
FAQ
Frequently asked questions
Do I need a check valve on my pool pump?
Maybe, and the pump may not be where it goes. A check valve lets water move one way only. Where you need one depends on what's on the pad. One heater maker's guide calls for a check valve between the heater and any chemical feeder. It keeps strong chlorine from siphoning back into the heater when the pump is off. The same guide recommends check valves anywhere water could siphon backward, and says that's most likely right when the pump stops. It also says not to put chlorine tablets in the skimmer. With the pump off, strong chlorine sits in the line and can corrode the heater. So look at what comes after the heater on your pad. If there's a tablet feeder or a chlorinator, find the check valve between the two. If there isn't one, tell the customer and quote it. For a check valve at the pump, follow the pump maker's guide for that model.
Does a pool heater need a bypass valve?
Only when the pump can push more water than the heater is built for. One maker's guide sets the top flow at 120 GPM for every heater size it covers. Above that, it calls for a manual bypass valve across the heater. The guide says pumps of 2 horsepower or larger can go past 120 GPM, and it recommends a bypass for those. The bypass sends the extra water around the heater. Whoever installs it adjusts it until the flow is in range. Then the handle comes off or gets locked, so nobody moves it. You'll sometimes find a valve by the heater with no handle for this reason. Don't move it. With too much water going around, the heater drops under its least flow and won't fire. With too little, it gets more water than it should. If the bypass looks like it's been moved, call a licensed heater tech to reset it. Other brands set their own numbers, so read the guide for the heater on the pad.
How do I know if my multiport valve is bad?
Look for water where it shouldn't be. One maker's guide lists the signs. Water running out the waste line while the valve is on filter means dirt or sand under the seal, a damaged seal, or a damaged valve body. Clean the seal area first. If it still leaks, the valve top or the body gets replaced. Water at the handle means a worn o-ring, and the guide's fix is a new valve top. Water where the pipes thread in means a cracked port or too little thread sealant. Water between the valve and the tank means the o-ring there needs a look. For sand in the pool, the guide sends you to the filter first. Before you open any of it, shut the pump off and open the air bleeder to let the pressure out. A valve that leaks at one o-ring is a repair. A cracked body is a new valve.
