I've got a power vent gas water heater that has operated perfectly for several years but lately been unable to start/stop without a racket.
The problem seems to occur when there are multiple short uses for hot water, i.e. weekends.
The vent fan comes on and off rapidly and the solenoid clicks like a machine gun. I can make the unit "fire up" by running hot water until a strong demand is created. I replaced the thermostat and gas control valve and solenoids. I've checked the air line and then replaced the air pressure switch and relay. I've had the gas company out to check the pressure which was 7" W.C. so now I'm lost.
Any experts out there?
I have contacted the manufacturer, who tried to help via email but gave up.
This last weekend it seemed to be having trouble while gas clothes dryer was running- Low gas pressure (in spite of measured 7")?

Is there a computer module on your heater? What brand and year is it?

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Originally Posted by MrPinMN

I've got a power vent gas water heater that has operated perfectly for several years but lately been unable to start/stop without a racket.
The problem seems to occur when there are multiple short uses for hot water, i.e. weekends.
The vent fan comes on and off rapidly and the solenoid clicks like a machine gun. I can make the unit "fire up" by running hot water until a strong demand is created. I replaced the thermostat and gas control valve and solenoids. I've checked the air line and then replaced the air pressure switch and relay. I've had the gas company out to check the pressure which was 7" W.C. so now I'm lost.
Any experts out there?
I have contacted the manufacturer, who tried to help via email but gave up.
This last weekend it seemed to be having trouble while gas clothes dryer was running- Low gas pressure (in spite of measured 7")?

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Has anyone checked to see if the burner is properly aligned and not rotted out?

Doug238- there is no computer module. It is a State Censible Power Vent originally installed about 9 years ago; Model PRV 50 NOV T1, 40,000 BTU.

iamgrowler-
When I replaced the thermocouple and gas valve 'y, everything around the burner looked good. Again, my problem seems to be when there are short recurring calls for heat. This morning with three hot showers- there was no problem.

Thanks for your help.

I have thought about this all day. I don't know much about them. I have only worked on 2. however, it sounds to me like that you have replaced all the parts. I keep going back to the actuator, the air hose. Is it leaking? Is there something concerning the actuator [air hose] that is malfunctioning?

Doug238-
When I replaced the thermostat and gas valve, I took a close look at the hose/airline. It didn't seem to have any cracks and I trimmed off abit on the ends to make sure I got a gooc seal when I reattached it.
I happened to be around yesterday when the "machine gun" started up.
I unplugged the unit from the outlet for about 10 sec. It started up normally right away.
Thanks for your thoughts.