# AO Smith issues



## plumb nutz (Jan 28, 2011)

Seriously, I really don't want to hear about AO Smother being crap or how great BW are... And honestly, looking for techs who have worked on commercial AO Smith heaters...

So I gots me a BTR 365 118 heater that wouldn't fire up. The dampner is on manual bypassing the open/close switch as there is a blower fan tied further up the flue which we have tied into the dampner wires.

Reset the heater, calls for heat, but does not energize the pilot assembly. Have 24v going to the ignition module from the thermostat control, but only 14v to the pilot and gas valve. Figure the ignition module was bad. Replaced that and the pilot assembly (found out the pilot tube was linked so just changed it out for s&g) and at first got it to spark but not catch. Reset 3 times with the same results. Disconnected the pilot tube from the valve to check for gas, nothing there. Pulled the plug on the test tee, have plenty of gas available. Checked the voltage again with the same 24v and 14v.

Since I had to cross state lines to get new parts switched out the thermostat control (bad transformer?) and ignition module. This time I checked the voltage before firing. Have 24v at the module and at the pilot but 14v at the valve. This new module has the indication led. Get 6 flashes (internal error) for s&g reset the heater and pulled the wire to the gas valve. Unit went into continuous spark. Put the wire back on and the module went into failure...

Leaning towards the gas valve being replaced, but because there is no way to test (that I know of or can find). Worst part is the nearest replacement is in BFE S. Carolina. Boss ordered the part and hopefully it will be here in the morning...

Just wondering if there might be something I missed, or any other ideas...


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## Plumber Jim (Jun 19, 2008)

Take a look at this. It is the service manual.

http://www.hotwater.com/lit/training/317917-000.pdf


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## Plumber Jim (Jun 19, 2008)

It is possible you got a bad module from the supply house.


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## plumb nutz (Jan 28, 2011)

Yea... Looked at that but no... That's the old style. Like everybody else they change the product and forget to update the manuals.


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## Greenguy (Jan 22, 2011)

My self when I replace a tank IDC what brand if the module is good I take it and any other decent parts, the idea being when you run into an issue like this I can do a quick switch of the module and test, also it let's me start to reheat the tank while I fetch a replacement part.


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## Plumber Jim (Jun 19, 2008)

Ok, so you set it up to call for heat and it starts and you get 24v to the pilot and you get it sparking? but no 24v to the main valve?


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## Redwood (Sep 8, 2008)

If you disconnect the wires to the gas valve does the voltage coming out of the ignition module to the gas valve go up to 24 volts?


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## Plumber Jim (Jun 19, 2008)

Redwood said:


> If you disconnect the wires to the gas valve does the voltage coming out of the ignition module to the gas valve go up to 24 volts?



I think he is getting 24v to pilot. It shouldn't send 24v to the main valve till it proves it has a flame.


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## Redwood (Sep 8, 2008)

Plumber Jim said:


> I think he is getting 24v to pilot. It shouldn't send 24v to the main valve till it proves it has a flame.


Right, but he needs 24 volts across the black wire and the blue wire to open the pilot valve.


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## Plumber Jim (Jun 19, 2008)

Redwood said:


> Right, but he needs 24 volts across the black wire and the blue wire to open the pilot valve.


To tell you the truth I don't have the colors in my head. lol but, If I read his post correctly he said he had 24v from the pv port on the module. so the next question i have assuming he checked the other end to make sure that 24v got to the valve and it's not a bad wire or connector. does he get spark. assuming his meter can check that.


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## Plumber Jim (Jun 19, 2008)

Ok, I reread the post. you said you had spark but no flame so you disconnected the pilot tube and had no gas going to the pilot even though it had 24v you you in deed checked the 24v from the valve side of the wire and know the valve got the 24v then i would check the gas valve. page 30 of that manual should explain how to test that.


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## Redwood (Sep 8, 2008)

Coming out of the ignition module going to the gas valve:
PV is black
MV is yellow
PV/MV common is blue

Disconnect them and see if the the voltage on the black and the blue wires at the gas valve is 24 volts...

Reconnect and the voltage drops.

Prolly a shorted coil in the gas valve, and there is a current limiting circuit in the ignition module so the shorted coil causes the voltage to drop...

BTW did I already say AO Smith SUX... :laughing:


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## Redwood (Sep 8, 2008)

If hooked up on both ends and he has 24 at the module and 14 at the gas valve then there is a bad wire...

To check the wire use the voltmeter with one lead on each end and a good wire will read 0 volts with power applied...

A bad wire will read a voltage in this case the "lost" 14 volts...


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## Plumber Jim (Jun 19, 2008)

Redwood said:


> Coming out of the ignition module going to the gas valve:
> PV is black
> MV is yellow
> PV/MV common is blue
> ...


Yup, That is what i meant. he should have 24v from the wire on PV and the common PV/MV 

plumb nutz, Let us know how it goes.


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## Redwood (Sep 8, 2008)

Just a guess on my part but they may use the same coil size for both the pilot and main valves. you may be able to compare the resistance readings on the coils and see if one is a lot lower...

But that is just a guess without having a lot more information on the gas valve...


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## revenge (Jun 30, 2011)

On the gas val-e ther should be a plug with a allen wrench remove screw and check inces of water columon the sticker with serial and model # and check wat manifold pressure is needed for example a 40 gal ao smith needs 4.0 so if my gage reads 3.5-4.0 then gas v alve is good but if all else fails call. 18663629898 that is teck support I had same problem as you changed at all these parts I found that number diagnosed 3. Heaters less than an hour with part numbers let me know how it /oes


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## plumb nutz (Jan 28, 2011)

Update: waiting for the part to come in...

Went onto the honeywell site and reading through their trouble shooting website, it attributes the drop in voltage to the gas valve...

Thanks for the advice...


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## U666A (Dec 11, 2010)

revenge said:


> On the gas val-e ther should be a plug with a allen wrench remove screw and check inces of water columon the sticker with serial and model # and check wat manifold pressure is needed for example a 40 gal ao smith needs 4.0 so if my gage reads 3.5-4.0 then gas v alve is good but if all else fails call. 18663629898 that is teck support I had same problem as you changed at all these parts I found that number diagnosed 3. Heaters less than an hour with part numbers let me know how it /oes


Wow Revenge, so informative and yet so impossible to decipher... :laughing:


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## Redwood (Sep 8, 2008)

U666A said:


> Wow Revenge, so informative and yet so impossible to decipher... :laughing:


You couldn't understand that? :whistling2::laughing:

He said:



> Originally Posted by revenge
> On the gas valve there should be a plug that unscrews with an allen wrench, Unscrew the plug and check how many inches of water column you have. The sticker with serial# and model# is used to find the correct chart. Check the manifold pressure and it should be within what the chart says. For example a 40 gal AO Smith needs 4.0 inches of water column. If my gage reads 3.5-4.0 inches of water column, then gas valve is good. but If you still have problems call 1-866-362-9898. That is Tech Support phone number. I had same problem That you seem to have, I changed all sorts of parts. I found that number and diagnosed 3 different water heaters less than an hour, with with them telling me the part numbers I needed. Let me know how it Goes


Don't you know how to read? :laughing:


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## plumb nutz (Jan 28, 2011)

Got the gas valve, slammed it in, fired it up, and walked out the door...

Thanks again for all the input. Learned a few things on this one...


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