Water Heater Wont Fire On Gas

[dano73]

I have a 2002 5er with a 10 gal atwood water heater. It works fine on ac, but about a year ago stopped working on gas. Everything else in the trailer works fine on gas, fridge and stove. It sparks fine and tries to light, but goes into lockout mode after 3 attempts. I have replaced the thermostat and eco, there is voltage at the solenoid and I hear that distinctive click when the heater is turned on. I also replaced the board today with another known good one, but it did the same thing, 3 attempts and lockout, which I tried multiple times. I cleaned all grounds and used those grounds to check voltage at the solenoid, and they worked. I also cleaned the nozzle in alcohol, still no go. Any ideas?

[Gjac]

I addition to what was already suggested I would clean off all the ground wires. Especially the one to the gas solenoid. On mine it was a green wire and was hard to see in back of the bracket that the solenoid was attached to. Be careful not to twist the wire out of the solenoid when loosening the star nut holding the ground wire.

[mikestock]

I had a problem, at one point, with a tiny dirt dauber nest in the burner but if you checked for spider webs you probably would have discovered if that was your problem.

[dougrainer]

Have you cracked open the supply LP line to verify you DO have LP to the input of the gas valve?? You may have a clogged or smashed/crimped LP supply line. Doug

[BrianinMichigan]

I had one of the two coils go bad. It does sound like the gas valve is working. You will have to do a resistance check on both of the coils. I believe one was around 90 ohms the other one was open. I bought some magnet wire and rewound the bad coil. It has worked fine ever since.

[DaHose]

I had one solenoid go bad in my setup. I could make one click, but not the other. My water heater is so old that replacements cannot be found. I fixed them both by purchasing two new solenoids, using the coil from one on an existing body (I bypassed the second) and putting the second new solenoid about two feet further up the gas feed line.

That's when I discovered it would fire up, then shutdown 10 seconds later. A new board fixed it all.

Jose

[Chris_Bryant]

dano73 wrote:
OK, I haven't had time to check today, but I know I checked 1 an there was 12 volts, besides would the solenoid click open if there was no power there?? and the board is definitely good.

That is a redundant valve- there are 2 solenoids. You can here one click, but the second can be defective, or sticking.

[dano73]

OK, I haven't had time to check today, but I know I checked 1 an there was 12 volts, besides would the solenoid click open if there was no power there?? and the board is definitely good.

[DaHose]

I agree with Chris. Check for 12V at the solenoids. If it's there and they don't open, the whole solenoid assembly is $60-$80 and easy to replace. If you don't have 12V, then jump the solenoids from a battery. If they open, then you likely have a bad board. Dinosaur electronics replacement boards are great and they run about $80.

Jose

[Chris_Bryant]

Either the valve is sticking, or one of the coils is bad on the valve. Check the continuity of both coils.

[dano73]

But if the thermocouple/ignitor was bad, wouldn't the flame ignite and then go out, since the thermocouple was not sensing a flame? Also theres no way the board I used for testing was bad, I fired the other water heater with it, before I took it out.

[azrving]

dano73 wrote:
There are no webs in the burner tube. I don't see a thermocouple, is it part of the igniter electrode?

Yes, it probably is part of the ignitor. When the flame hits it there is a millivolt signal sent to the card.
I went through all that with mine. I checked all the connections, cleaned everything, replaced the ignitor and in the end my board had to be bad. I replaced the whole water heater as I didn't want to chance buying more parts for an old water heater. You say that you replaced your card with a known good card but maybe it isn't good?

[dano73]

There are no webs in the burner tube. I don't see a thermocouple, is it part of the igniter electrode?

[nineoaks2004]

You might check for cob webs in the burner tube, spider webs will not burn, I use a small round brush. Also the thermocouple might be bad, if it is just dirty you can carefully polish it with steel wool.

[dano73]

Idk would the thermocouple be part of the ignitor electrode?