No pilot sensed AFTER heating for 10-15 minutes

[christo]

changed the unitherm governor (which was quite corroded) and i STILL get hi limit 2 after 15-20 minutes and 93 degree water followed by no pilot sensed.
ugh.
this is NOT intermittent.
after everything cools down - it repeats the cycle - spark - heating - hi limit - cool down - no spark - more cool down - heating.....
you said "bad internal bypass" is next?
how could this bypass be the problem?
same issue as the unitherm? the unitherm was never open enough so the hi limit was reached.
now with the new unitherm is the problem that the internal bypass is not operating correctly allowing the hi limit to be reached?

 

[JamesW]

It's good that you replaced the unitherm governor. Since it was corroded, it was probably trapping water in the exchanger causing it to overheat.

Since you're still getting a high limit error, it might be a bad high limit sensor or the water is still overheating.

Overheating is usually a bad unitherm governor, bad internal bypass or low flow from the pump being set to too low rpm or scale in the exchanger or a dirty filter.

Make sure that the flow is good going to and coming out of the heater.

As long as the flow is good, the next thing to check is the internal bypass and check to see if the exchanger is scaled.

 

[christo]

i guess i'm taking off the header...
in this video

- which is for a different model - the retrofit part has a painted spring.
but the only part i can find is raypak 006715F which does not seem to have a painted spring - there are 2 different colors. is one coated?
my pool is salt water.

 

[JamesW]

That video has nothing to do with your issue.

This video shows how to remove the headers. You only need to remove the inlet/outlet header.

006715F should be the correct part number for the bypass kit.

The high limit (P/N 600893B) should trip at 140° Fahrenheit. So, it would indicate that the water in the heat exchanger is exceeding 140°. You could remove the high limit sensor and test it at various water temperatures to verify if it's working correctly. It might be tripping at a lower temperature than 140°.

With the header removed, you can look inside the heat exchanger tubes to see if they are scaled. You can remove the back header if you want to look through the tubes.

Get new gaskets before removing the headers.

 

[christo]

sorry - wrong video. here is the one with the yellow spring...

 

[JamesW]

That's not relevant to your situation.

In the video that I posted, you can see the bypass by looking in the outlet.

You can check the bypass by looking in the outlet and inlet.

If you're getting a high limit error, it might be a high limit sensor going bad or low flow from a pump set too low or a dirty filter or scale in the heat exchanger or a defective internal bypass.

You're going to have to check everything until you find the problem.