Hayward H100ID sometimes ignites, doesn't stay lit - gas?

[joshuam]

Hayward H100ID Propane. Ignites occasionally, but doesn’t stay lit.

Has worked for ~1 year no big problems, just the usual annoyances.
All switches/safeties are functional, and not jumpered.

Heater correctly spins up fan and calls for heat.
Propane begins supplying. However, ignition does not occur.

Ignitor is sparking. I have pulled the ignitor, and verified spark, as well as cleaned off white deposits.
I have pulled the burner tray; cleaned a tiny cobweb from one orifice. There is some cruft in the heater box, but not an enormous amount. The burners are clean; I didn’t pressure them out with a hose, but did seal the entry and blow through them and they seemed fine.

Input gas pressure is ~9”Wc.
Output gas pressure is low; 1” WC.

I removed the dust cover on the adjuster cap. Turning the needle valve adjustment, however, seemed to make no difference. One oddity: backing the screw OUT (left) seemed to shut the valve: gas dropped to .25” and was intermittent and gas smell was faint. Turning the scren IN (right) seemed to increase gas flow, but I couldn’t get it past 1” no matter how far dialed in it was.

Initial setting was 3 ½ full turns out from bottom, and I have returned it to that.

Heater ignites occasionally, but doesn’t stay lit.
Love a sanity check/ideas on this one. Thanks!

 

[ps0303]

Re: Hayward H100ID sometimes ignites, doesn't stay lit - gas

Unless you now for sure what you are doing, don't mess with the gas. Obviously you haven't worked on these before or you would know that screwing it IN increases the pressure.

What about the regulator(s)? Get your propane company involved if you lease the tank. Have them check the pressure.

 

[Bama Rambler]

Re: Hayward H100ID sometimes ignites, doesn't stay lit - gas

Gas pressure should be 11" WC. I just want to reinforce what Paul said, unless you're very familiar with gas systems, call a repair person. Don't try to repair it yourself.

 

[joshuam]

Re: Hayward H100ID sometimes ignites, doesn't stay lit - gas

Spec for this unit is, IIRC, 3-13" WC with propane, 13" being the hard maximum.

The 11" is a nominal, and used for distance/diameter estimates of the supply tube in the manual, but the device is designed to work at a theoretical 3" WC pressure (same page). Not that I'd expect that to actually work, but 9.5" is sufficient. And has worked for a year, so is probably not the problem!

Similarly, pressure on the tank has checked out fine, otherwise this would be a much simpler situation.

Other needle valves I've worked on have screwed in to close the gap between plunger and shoulder. I was only curious.

I will be trying another regulator, but since this one worked one day while I was testing a replacement heat exchanger (an apparently unrelated problem AFAICT), and this problem developed the next, I am doubting it - though I will get back with hard data.

Thanks for the advice, guys. Any other thoughts?

Given the sudden onset, I'm wondering specifically whether something has gotten into the gas valve. I've never seen inside one of these, and don't plan on seeing inside this one, but if someone here has that experience and can speak to whether these symptoms would follow, I'd greatly appreciate it.

Alternatively, perhaps something has - somehow? - gotten into the regulator. That would be much easier to deal with, and if the new regulator solves the problem, I'll know that was it. I would expect a plugged regulator to be completely unreliable, though, and this one seems to be delivering sufficient pressure to the supply side of the gas valve. Given the gas valve is (usually) a much larger opening when that solenoid clicks over, I expected that any debris would fall into the needle valve - unless there's something in the gas valve designed to prevent it. Does anyone know whether there is? Is this a possibility I should cross off the list? I wouldn't go there, but as you see, most everything else seems fine.

 

[joshuam]

Re: Hayward H100ID sometimes ignites, doesn't stay lit - gas

New regulator makes no difference on the output side - so I'm concluding that the problem is with the gas valve, somehow.

I'll update this post with more later on, as it may be useful to people who are exploring issues like this. If anyone has actual knowledge about any particulate filters/etc in the gas valve, I'd love to hear them.

As a side note, this is the second time I've posted a technical question here and gotten answers that weren't correct, or had misread the manual or the data I had observed, but were delivered with total certainty. I think this may be counterproductive for some people. (The last time, someone wanted to explain why a small propane can *would not* work and violated a few rules of physics to tell me why. He was, of course, incorrect, as a year of running a hot tub in a difficult location off hand-carried propane cans or a few minutes with a calculator and the ideal gas laws can attest, but he was quite strident along the way.) Probably, since we're all working on the same empirical question, this kind of thing wasn't necessary.

It's a tremendous service you guys with significant experience do when you take time to answer people's questions, but it may be better to not answer than to just repeat misreadings, like the idea that pressure must be exactly 11" WC - bogus even from a reading of the manual, as well as my own experience. It's no crime to say "I don't know.", or to ask questions rather than make pronouncements.

Again, I'm happy for the input and knowledge that is shared here, but I must say I do find the delivery a bit much at times. Hope I haven't further ruffled feathers by saying so.

Thanks again;
j