An issue with our Hayward H400

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sbagdon

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Jul 21, 2009
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We're having an issue with our Hayward H400. Pool was closed for 3 seasons, just finally opened it again. Heater is dual thermostat (pool/spa), yellow "System Ready" and green "Heating" light, twin-position switch (pool/off/spa), 8 combustion chambers, with DSI. No water leaks, a little dusty, many webs. Gas pressure is good, valve functions normally. Would not light at first, verified DSI spark generator is working. Now it'll light about every 5th time, with a big poof. When it doesn't light the gas valve will close after about 2-3 seconds, if it does light the gas valve will close after about 5 seconds after lighting.

Guessing either the gas jets, or the combustion chambers, creating a bad burn environment. Do either of these go "bad" (corrode, chip, open/close holes, etc), or are they manufactured enough that a good cleaning will fix these issues? The gas nozzles appear removable without much work, it appears to repair/replace the chambers will require removing the gas valve/piping (ugh!).

Any ideas on why the unit is turning off after 5 secs? Reviewing the wiring diagram (inside of upper control panel), it doesn't appear to show any flame sensors. There appears to be two thermo sensors, in-line with two water pressure sensors, in-line with a water temp sensor, leading to the "System Ready" yellow light. Yet the diagram shows "closed" being normal for the thermo sensors, and "open" for the water pressure sensors, so I'm presuming they are over-heat sensors, not flame-sensors. Where's the flame sensor?

Thanks!
 
Re: Hayward H400 Ignition Failure

Well, that explains the missing flame sensor. Duh. :)

Any input on the poof? I'll do a good cleaning this weekend of the jets and combustion chambers... has anyone seen them go bad enough to require replacement, even after cleaning?

Any good/cheap sources for Hayward parts(for the pilot tip)?

Thanks!
 
I would go ahead and buy a ignition assembly I done it on my h250 and now works like a charm. I beleive the POOF is form the pilot hosing being bad or cracked.It should come with a new sensor/pilot tube and igniter.
 
Turned out to be just plain dirty. Got pressed for time, heating company came out and gave it a pro cleaning. They said the combustion chambers were clogged with cobwebs. After a pro cleaning, it passed 10 cycle tests, and they left. Tested myself later that day, now outputting wonderfully warm water out the jets, no issues firing. This heater is built like a freakin' tank... almost 10 years old, 3 of them with the pool closed and the heater never touched. This is the first time the access panels have been off, since installation. Can definitely recommend old-school Haywards (can't speak on units with all-digital controls).

Thanks to all who replied!
 
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