Quote Originally Posted by Pool Clown View Post
You guys are probably right.

But in another circumstance, there is the possibility that one of the by-passes, the flow, or the thermal, that could be the cause of the boiling. This will usually cause the heater to short cycle.

My money is on the calcium.

I post this for others that may have a similar issue without the water chemistry problem.

"Just a clown talking, ignore him. "
It's not short cycling....I ran it Saturday all day and it ran fine, over 8 hours it raised the water temp probably 10 degrees (about 10000 gallons). It started right up and I checked it everyone so often, the fan and burner stayed on and ran with no issues. It just sounded like an old boiler, making these knocking sounds like a rock or something is in a pipe.

The season here in NYC is almost over - that is, 2/3s of the kids are back (away) at school already and my 3rd starts in a couple weeks. So once I close up in the next couple of weekends, I'll take the heater into my workshop and take it apart and report back on my findings.

Thanks again,
Phil