troubleshooting pool heater

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Troubleshooting pool heater

Postby Me... » Fri 09 Oct, 2009 09:40

Jayss wrote:First you need to check the thermopile at the gas valve and make sure you at least 500 millivolt.

3 points for Jayss! Make sure the TP leads are not connected to the gas valve when testing. If its a good solid 500 or more look for loose/corroded connections. Heck, tighten them all anyways. The diaphragm in the gas valve can stick closed if it remains shut for a long time. A **gentle** tap with a screwdriver handle under the gas valve might free it. If so turn the thermostat up/down several times to help make sure it stays that way. DO NOT try to disassemble the gas vlave.

Firing the boiler with low water will flash the water to steam which is an explosion, especially in the confined area of a heat exchanger.

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Troubleshooting pool heater

Postby Pool Clown » Fri 09 Oct, 2009 11:46

I'll admit i'm wrong, If you can prove it. So far, I have seen no proof. I've asked you where you got the "metal expands rapidly" theory from, But you won't tell me. Why? I have told you where i got my information from.

Raypak will be putting on free, half day seminars this year across the country. Please go to one in your area, and talk to Tom Apt (instructor) privately, if you don't want to ask in class.
Ask him, "What the banging is" ?
Factory warranty service for Pentair, Jandy, Raypak, Polaris, and Paramount pool cleaning systems.

troubleshooting pool heater

Postby PoolPro » Sat 10 Oct, 2009 01:55

It has always been obvious to me what the banging was. The water flowing through the heat exchanger keeps the heat exchanger below the temperature that would cause damage. A similar effect can be seen by holding a flame under a paper cup full of water. The paper does not burn through because the water absorbs the heat very effectively.

If the water stops moving, it heats up very quickly. At some point, the temperature of the exchanger gets too hot and it expands and warps. If the water does boil, it becomes steam. Steam has virtually no capacity to absorb heat from the exchanger, and the exchanger would get much hotter, much faster.

Therefore, if someone were to tell you that boiling water caused the banging, they would not necessarily be wrong, but they would not be exactly right either. The same thing would happen with no water.

If you hear banging sounds in your water heater, it is most likely due to metal parts that are expanding and contracting.

troubleshooting pool heater

Postby toofunny » Mon 06 Jun, 2011 18:28

Too funny does it have to end???
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troubleshooting pool heater

Postby IndoorPoolGuy » Sat 10 Mar, 2012 20:43

Hi toofunny! Have you checked this guide to swimming pool heaters at

troubleshooting pool heater

Postby habby » Wed 05 Jun, 2013 22:43

you could test components for continuity to see if the component or switches are closed. If there is an open circuit that usually indicates what component or switch is faulty.IF everything tests ok, then it could be something with the gas valve

Re: troubleshooting pool heater

Postby Mikhubb » Sun 09 Jul, 2017 22:49

This is a new question about a Jandy Lite2 (LG175NG).
The pilot will stay lit and when I jumper TH to PP-TH the boiler runs fine.
I have gone through all the testing of the millivolt system and here is where I get stuck/confused.
At the end of the black TH wire I have 520 millivolt. When I attach the wire to the TH terminal and the test at the terminal I ONLY see 48 millivolts.
What could be going on here?
What could be wrong here?
Thanks for any help.
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Re: troubleshooting pool heater

Postby Ethan Miller » Thu 08 Feb, 2018 22:05

Swimming pool heaters are the most complicated piece of pool equipment on you pool equipment pad. Making repairs to pool heaters should be performed by qualified personnel. Gas pool heaters using Natural Gas or LP (Liquid Propane) gas can be hazardous by combustion or exhaust of the pool heater. Hayward pool equipment had created the Pool heater FAQ below to help the pool owner with pool heater repairs and pool heater troubleshooting.

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