Question about Hayward Pool & Spa

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I have a Hayward H400 pool heater. I don’t heat my pool so I never use it but I do turn it on once or twice a year for about five minutes to make sure it’s working, which right now it fires up just fine. The problem I am having is once the pump turns off, the blower on the heater turns on & stays on. I can’t get it to turn off unless I cut the power. This is obviously a problem because I can’t have the pump on a timer because as soon as the pump turns off, the blower on the heater will run for 16 hours until the pump kicks back on. I’ve done a lot of research & can’t find a solution or anyone who has experienced this problem. Any advice would be appreciated.

Posted by Kory Collins on


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Rudy Lorenz

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Find the wiring diagram in the unit or on line. look to see how the fan motor is controlled. Check those controllers to make sure they are working properly.

Posted on Aug 12, 2019


Michael Prior

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Call a qualified electrician. More information would be needed to accurately trouble shoot your issue. Do you have automation connected to your heater? Is the heater trying to fire when the pump is off or is it ONLY the fan?
Try disconnecting your Water Pressure switch on the heater and see if the issue stops. With WP switch disconnected the heater should not work and the fan should stay off. Replace WP switch and see what happens.
Call a QUALIFIED electrician.

Posted on Aug 07, 2019


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SOURCE: hayward pool heater h series

the issue is a broken baffle in the system. there is a baffel that directs water into the heat exchanger and back out into the system. The welds that hold the baffel in place have broken off. It can be repaired if you take the unit to someone with a mig welder and have them re-weld it (muffler shop, mechanic?). there needs to be a weld on both sides. You can see the baffel if you remove the unit and look down the inlet and outlet tubes.

Posted on May 25, 2009


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SOURCE: 1 year old hayward h1001d pool heater clicking

see this link ....

Posted on May 25, 2009


John Prohaska

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SOURCE: 1 year old hayward h1001d pool heater clicking

Actually, the clicking is likely causing the shaking. Inside the manifold of a H100 is a stainless steel diverter plate that send some of the passing water into the heat exchanger and lets the rest past and back to the pool. When it breaks, you will hear a 'clicking' noise at it rattles in the water path. When it breaks, the flow to the heat exchanger is intermittent and you will begin to boil the water, causing the shaking. This situation is dangerous, especially without a pressure relief in the heater or pipe. As long as your water chemistry is sound, Hayward will usually cover this under warranty even if the unit is over a year old. Contact them to get a factory authorized repair rep out at:

Posted on Jun 12, 2009


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SOURCE: Heaters fires, stays on for 10 seconds, then burner turns off

Just had the same experience.
1. Pull the top cover off and try gently wiggling the printed circuit board on the right side top. Pull the thermostat mounting board too if it helps. Be careful as it is still live as you are doing this. If it fires, unplug it & remove the board from the unit. Get a magnifying glass and a good light and go over the solder connections on the back of the board, ALL of my connections where the harness plugs into the board were cracked. Best as I can figure, the board is mounted right next to the power vented flue discharge and it is extremely hot there and must expand & contract with heat especially if wind is blowing the heat back onto the unit. Re-solder connections & mount the board somewhere else in the unit.
2. The igniter assembly acts as a thermocouple, which is to say it "proves" the flame to the unit telling the gas valve to stay open and the spark to shut off as long as the thermostat wants the unit to run. That component may have failed & requires replacement.
3. The flow switch (Pressure sensor) proves water flow to the unit saying it is ok to fire. I've replaced mine twice due to them busting open, but that can also hold out the unit if it doesn't sense flow,however but I doubt that is the culprit. It is easy to test, just make sure the pump is on, jump the wires & turn on the unit. MAKE SURE to put them back on after testing as the water will boil very rapidly if the unit runs with no flow which is extremely dangerous.

I would check these components in that order.

Posted on Jul 14, 2009



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SOURCE: I have 7 year old Hayward ProSeries, S-244S, H/R Sand filter. I've notice that when I vacuum the pool, dirty water returns to the pool. I've backwashed and the spider gasket is fine. No sa

sand filters only have limited filtration. If the dirt is very fine such as dead algae, it will go right through the filter. Use a clarifier to help give the filter finer filtration. Do not vacuum until you can see what you are doing, then vacuum on 'waste'

Posted on Oct 12, 2012

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