Simple solution to fix a pool heater ground problem


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TFP Guide
Oct 25, 2015

When I went through recent lightning strike and subsequent self-inflicted short of the entire pool heater electrical I learned a neat little trick to solve the well-described ground issues that can cause the flame sensing circuit to fail. So I'm documenting it here to make it easily searchable. I found this documented on Fenwal's website technical support literature. Fenwal manufactures the ignition control module for many different pool heaters. Pool heaters often have a lot of ground wires that run from every different part of the metal firebox and sort of daisy-chain back to the control system ground. Problem is that severe service combined with a few small leaks can leave the heater a corrosion mess in short order. The ground system is a very critical component for heater control since it works by producing a tiny signal to ground and then the control module detects it to be sure there's a flame. This technology is incredibly reliable so long as the ground system has no interference from corroded wires. If it doesn't detect this tiny signal (about 2 millionth's of an amp) due to corrosion the system will keep the gas valve closed. To positively fix this you just run a wire from the burner base or from the burner flame holder on many of the new high efficiency heaters to the ground connection on the control module.

Pentair actually sells a ground wire kit to accomplish this. Here's a photo from their kit instructions:


Here's an alternate location (I added both on my heater just to be certain I'd have the ground signal):


I've attached a copy of the Fenwal technical article and the Pentair ground wire kit instructions.

I hope this is helpful.



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Bronze Supporter
Mar 5, 2017
Palm Desert, CA
That’s a good tip. I’ve had to do similar as ground locations have rusted. A sheet metal screw with bare threaded wire wrapped around (drilled into sheet metal) may help to get it anchored better.