A.O. Smith power shot FPSH 75 271 doesn't stay running


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Old 10-11-13, 04:55 PM
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A.O. Smith power shot FPSH 75 271 doesn't stay running

I have a a.o. Smith water heater that won't stay running to it meets the temp. It will start and run for about 4-5 mins. Then it will shut off and try to restart. Sometimes it won't get to flame on stage after it tries to restart. It will try 3 times then go into lockout. Any idea what would be causing this? The unit was installed in 2005. It's a propane water heater.
 
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Old 10-29-13, 09:13 AM
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Still not having any luck. I did a ohm test on the flame sensor when it was cool and got 17.3 ohm's. I then did one when the water shut down and got 45ohms. Is the flame senor kicking the unit off before it has reached temp?
 
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Old 10-29-13, 09:17 AM
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What style gas valve? Is that a smart valve with a grn light?

If so I believe it has the machine gun barrel type igniter. There are two versions if you get an igniter replacement. Then run $50 bucks or so...

IMO I would maybe not throw money at this heater and replace...

Smart valve PCB's were known to fail with bad thru hole solder joints where the molex connects internally...
 
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Old 10-29-13, 09:40 AM
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not sure what valve I have. it has the vacation setting and two touch pads for change the temp setting. a, b, c settings. The igniter isn't the barrel type. Its a flat rod and the flame sensor is round with a bend.
 
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Old 10-29-13, 10:32 AM
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OK here is the service handbook but the one for your heater will not open... E mail AO smith and have them e mail you a copy... From there you can diagnose yourself....

Most common is the flame sensor which is part of the ignighter.. Comes as one assemble. You can look through other handbooks to read how to test....

Next common issue is the fan gets weak and will not activate the pressure switch.. Or the switch itself can be defective..

Last the wire harness from the fan to the gas valve fails... It runs internally in the tank... O often cut both ends at the tank and install new harness when they fail...

From memory I believe igniter $50 fan $250 and harness $50... But I am only going from memory...

New heaters retail for $900 I believe in that flavor....


Service Handbooks | A. O. Smith Water Heaters
 
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Old 10-29-13, 11:42 AM
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Thanks, I'll give this a shot.
 
 

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