How friendly is your local gas provider? Atlanta gas light actually came out and found my feed hose was bad and replaced it for free. It did help a church friend knew the tech that came out 
Intermittent ignition failures on Hayward 400FDN heater
- Thread starter cptkirk
- Start date
MITBeta
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- May 28, 2020
- 1,239
- Pool Size
- 13000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
Most gas companies are required to respond to gas issues of any kind. Generally, if they can easily make a repair, especially a leak, even on customer piping, they will. Otherwise, they will "make safe" and red tag the equipment for the customer to have repaired.
It looks to me that from the spec sheet for the regulator, it is undersized for this heater. Its capacity is 386 CFPH, but further down it says that its recommended to only run at 80% of capacity (which is 309 CFPH).
Edit: never mind I see that for an inlet pressure of 2 PSI the capacity is 1500.
Edit: never mind I see that for an inlet pressure of 2 PSI the capacity is 1500.
I have some plumbers coming out on Thursday to change out the regulator and clean up the supply. I'm hoping that will solve my problem. We've had great weather for the last several days, heater has fired successfully every time. I'll update the thread after the work has been done.
Plumbers changed out the regulator (same model as before) and reworked the connection from the regulator to the heater (eliminated the flex and added a union in the pipe section that connects to the gas valve). Did a test fire and the heater fired up smoothly. Now the input pressure to the gas valve drops to around 6" wc when the heater gas valve opens, whereas before it dropped to 1" to 2.5" initially. The real test will be when we have some damp weather again, but I'm hopeful the problem is solved.
MITBeta
Gold Supporter
- May 28, 2020
- 1,239
- Pool Size
- 13000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
What's the pressure before the valve opens? Are you seeing the spikes you were seeing with the old regulator?
When I had the manometer connected to the valve before opening the supply, it did spike up to around 50 wc" when I opened the supply and slowly bled down as before. Before I fired the heater, the plumber suggested to disconnect the manometer tube from the gas valve nipple briefly, re-zero the manometer, then reconnect it. After doing that, the pressure read just above 10" wc. I think the root problem is that the old regulator was just too slow to react to the pressure change when the gas valve opened. For whatever reason, the problem was worse when conditions were damp.
MITBeta
Gold Supporter
- May 28, 2020
- 1,239
- Pool Size
- 13000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
Sounds like you're on the right track. Can't wait to hear what happens when it rains!
Conditions have been abnormally dry here for almost three weeks. The heater has fired up successfully every time since the work on my supply was completed on May 20, but it hasn't passed the weather test yet. Pool temp has reached a level where my wife doesn't run the heater every day as she was previously, so the heater will probably not get much use again until fall. I still run it weekly for about 15 minutes on a schedule to keep it exercised. When we get some rain (not sure when that will be, forecast is not above 30% until next week), I'll update the thread with how it performs.
Since last night we are finally in a period of damp, rainy weather that has lasted for more than an hour or so. Test fired the heater twice today, both times without any problems. I feel safe now to say that the issue is resolved. It was not a problem with the heater itself, but with the high pressure supply regulator, possibly exacerbated by the sub-standard supply installation between that regulator and the heater.