A.O. Smith 50 Gal water heater not working regularly


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Old 10-12-11, 09:42 AM
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A.O. Smith 50 Gal water heater not working regularly

I have a 8 year old 50 gal A O Smith water heater (Model # FPSH 50 260) (Serial # MB03-2262171-260). The blower keeps going on for a few seconds or less. It turns on for a second and goes off, it does not give the igniter time to turn on to heat up the water. Every few hours it will run for a longer period of time (10-20 min) and lets the water heat. I replaced the pressure switch and temperature switch and that's not the issue (neighbor had same heater and I borrowed theirs). Its either the blower assembly or something else. I get three green led flashes and the manual says it could be the pressure switch, temperature switch, blower assembly, venting or flue temp). The venting seems to be ok, since I removed the venting off the blower and it kept on working the same. So there is nothing blocking the venting. Please help.
 
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Old 10-12-11, 10:27 AM
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Hi,

I would be leaning toward the pressure switch. Not that its not working but the fan lost enough cfm that it cant pull it in.

What I do is remove the hose at the flue that goes to the pressure switch. If you suck on this hose slightly you will here it click.

Either constantly suck on the hose to keep the switch close and try to light. If it lights successfully a few times you know its the fan.

That little barb filling where the hose goes to gets clogged also from condensate. So stick a small wire in there to clear it out.

The hose can be dry rotted or split. Check that.

Another way to check is to remove the exhaust off the top of the blower. This allows the fan to have no restriction and possible pull the switch in better.

The above should only be done to test breifly. Under no circumstances run the unit for normal use without the vent. You can be overcome by CO fumes and basically become dead......

My other advice on any smart valve units is to not throw money at it. They were AO smiths first attempt with this technology and is severly outdated. I highly recommend replacement of the water heater. Cut your loses. You got 8 yrs trouble free then you are one of the lucky ones.

Mike NJ
 
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Old 10-12-11, 11:31 AM
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Thanks Mike. I will try it later and let you know of my results.
 
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Old 10-14-11, 08:04 AM
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Hey Mike,

Thanks again for the tips. I tried all of your suggestions and it seems to be the fan/blower ($300 for a new one) that is bad. I went ahead and purchased a new one and had no problems since.

Thanks!
 
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Old 10-14-11, 08:17 AM
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I know they are expensive. I forgot to mention when I posted this
Another way to check is to remove the exhaust off the top of the blower. This allows the fan to have no restriction and possible pull the switch in better.
That the CFM of the fans get reduced and weak over time.

I am glad you figured it out.

Next is the gas valve. Those smart valves had issues and that you got 8 yrs out of it is pretty good. That is the more common failure I have also seen.

Good job!!!!!

Mike NJ
 
 

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