AO Smith GPS 75 200 Main Burners won't light


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Old 03-31-13, 06:48 PM
J
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AO Smith GPS 75 200 Main Burners won't light

This water heater is just over 1 year old (manufactured and installed feb 2012). No problems until now.

Here is what happens:
1) The unit comes on correctly during power on. (no error codes)

2) Blower starts up correctly

3) Hot surface ignitor lights up, but no flame is lit up.

4) repeats 3 times and goes to lockout (Error code #6: vacation and A & B lit up)

I tried the following:
- Can blow air through the pipe that supplies gas from main valve to burner - seems free enough
- I tried lighting the gas at the burner with a match - no success, it appears that there is no gas coming through. I can't smell any gas either.
- I do get gas prerssure coming to the valve from the flexible connector (though I have not tried to measure the pressure there)
- Observed the manifold pressure with a homemade manometer. No gas pressure during the 3 attempts to light.

My guess is the gas controller/valve may be faulty?
A service call is scheduled for later in the week and the unit is still under parts warranty (and pehaps labor too, if its not an installation issue).
Is there anything else I can check in the meantime?

I don't know if its related - but I noticed the problem the day after I replaced the expansion tank due to a dripping TP relief valve.

Thanks in advance,
John
 
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Old 04-01-13, 09:35 AM
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Most likley sound like the gas valve.... And I assume from your post you have the gas valve on the unit is on not off?

Additionally the gas valve on the line going to the heater is on?

Labor is only covered 1 yr. ( Make sure you call an AO smith rep and not a regular plumber)


I tried lighting the gas at the burner with a match - no success, it appears that there is no gas coming through. I can't smell any gas either.

No offense but that is just not smart.... Serious consequences, death, risk or explosion....etc
 
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Old 04-01-13, 09:50 AM
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Hi lawrosa, and thanks for the reply.

Not sure I fully understand your first question.

Answer to second question: Yes, the gas valve on the line going to the water heater is on.


John
 
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Old 04-01-13, 09:55 AM
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Yes Im sorry...Its an intellivent gas valve right? No on off on that valve...

Do you hear the gas valve click after the igniter glows and the HWH trys to light?
 
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Old 04-01-13, 10:00 AM
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White-Rodgers Intellivent, 9005964005 I believe.

Yes, I can hear the gas valve click as it tries to light.
 
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Old 04-01-13, 10:10 AM
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Does it light briefly then go out immediately? If so it may be the flame sensor.... This is part of the igniter.

I remember some of the 75 gallons had dual burners. Might have been the 100 series. Is this that type?

I was an AO smith rep but have not serviced heaters since 2009.
 
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Old 04-01-13, 10:30 AM
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No, it never lights. For that reason I have not tried to clean the flame sensor.
Mine is a series 200 and has dual burners.
 
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Old 04-01-13, 10:54 AM
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Odd that you here the click and no gas comes out. There is a thermal switch on the front door by the window. It has a small reset button in the middle. Did it trip? Try resetting it.

Otherwise if the igniter is glowing that means the fan and pressure switch are functioning.

Does this also have a vapor sensor? The vapor sensors when tripped though cause all the lights on the valve to light and permanent lock out. Special code to unlock the valve.

Not your issue but just saying.
 
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Old 04-01-13, 10:56 AM
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I don't think there is a thermal switch nor a window either on my model.
No vapor sensor either, I believe.
 
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Old 04-01-13, 10:58 AM
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Typically is was about $249 labor charge to change the gas valve. If your handy you can do it yourself. AO smith should sent the part at no charge.

To reduce the cost if you do use the Rep/plumber is to drain the heater yourself.

Additionally there should be no service charge added on to the labor cost. AO smith pays these reps/ plumbers 2 hours/$200 to go on these warranty calls.

Just saying....
 
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Old 04-01-13, 11:21 AM
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My understanding from calling AO smith is even though its technically 1 month beyond the first year labor warranty period they would waive any labor charge for me if it turns out to be a defective part and not an installation issue. I am basically trying to make sure it is a defective part and not an installation/ventialtion problem (or operator error). If its the former they assured me its no cost to me; if the latter the part is covered but not the labor.
Given that I'm not 100% sure what the issue is I can't just ask AO smith to send me the part and install it myself as it might not fix the issue. So when the repair man comes he may prefer to have the tank full to do the diagnostics?
 
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Old 04-05-13, 07:44 AM
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I had exact same problem, same error codes on same model, 2 yr old heater. After removing elect. connectors on bottom of control valve and making sure solid connection, burners finally lit on next try. Maybe just got lucky, but it is now working.
 
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Old 04-06-13, 02:16 PM
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The gas valve was replaced and now it works.

Thanks for all the help.
 
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Old 04-06-13, 02:25 PM
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Cool.... No charge?

Good job on the telephone with AO smith......
 
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Old 04-09-13, 04:14 PM
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Correct - no charge for parts, no charge for labor.
 
 

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