Camper hot water heater won't stay lit

[naylorchic]

Hi! I have a 1998 Prowler Travel Trailer. The hot water heater won't stay lit. I light the pilot, which stays lit fine, then switch it to on. It has a strong, roaring flame but goes out in less than 5 min. We lit & relit for an hour or two the other day, but it just keeps going out. Could there just be a lot of air in the line or something? Would it take that long to get it out though? Any info you could give would be appreciated. Thx!

[retired wrench]

Sounds like you have a bad thermocouple. Its a little bulb like thing that sets in the pilot lite flame with a tube that screws into the gas valve. RW

[naylorchic]

So the thermocouple controls both of the flames? The pilot stays on fine. After lighting it I put it on "pilot", came into the house, left it on for about 15 min & it didn't cut off. The problem is when I turn it from "pilot" to "on" so that the actual burner comes on. Is that part hard to change? Thx again!

[mla2ofus]

You probably have a wasp nest built in the exhaust tube and is starving the flame for oxygen due to exhaust gases staying in the combustion chamber.
Mike

[naylorchic]

Any tips on how can we try to clean that out?

[mla2ofus]

See if you can remove the exhaust grill on the outside and shine a flashlite in there to see if there is an obstruction. Maybe run a coatthanger wire down it to see what you can knock loose.
Mike

[naylorchic]

Ok thanx a million. We'll try that to see if that works. I'll let ya know.

[naylorchic]

We cleaned it out, but it's still cutting off. Have any idea where I can buy the thermocouple? Thx again!

[mla2ofus]

Well since you tried that and the pilot stays lit, try watching the flame when you have it going to see if it slowly gets smaller and smaller like it's running out of propane. If not and it just suddenly shuts off, then I'd say there's a problem in the heater gas valve. If it slowly shuts off, then get it relit and the main burner going again. Then lite a burner on the cookstove to see if it slowly goes out when the heater flame goes out. If this happens then I'd guess there is a problem in the propane regulator at the tanks. If the stove burner doesn't slowly go out then check the copper tube that feeds propane to the water heater from the main black pipe line.
Is this water heater equipped w/ electronic control board or just the old thermocouple controlled gas valve?
I'm sure the propane tanks have the new style valves. Try switching tanks. Sometimes those valves can be a PITA causing the symptoms you describe.
HTH,
Mike

[naylorchic]

We have watched it and it doesn't get smaller & smaller. It just shuts off (the burner & the pilot), but it we leave it on "pilot" the pilot stays lit. It's after we switch it to "on" that it cuts off. We have tried the stove & it works fine & so does the furnace. So I guess it's either the gas valve or the tank. It is the new style tank. If it were the tank would the stove & furnace still work ok? The water heater doesn't have an electronic control board that I know of. It just has the little dial-like knob, you put it to "pilot" hold it against the stop & light it, let go after 30 seconds & if it stays on you switch it to "on" to turn on the burner. That burns fine for a little while. If it is the gas valve do we just have to replace it? Thx!

[mla2ofus]

It sounds like the heater gas valve or thermocouple. Try replacing the thermocouple first since it's the cheapest, tho I doubt it is the problem. If that doesn't fix it then change the valve. Be aware the hot water tank must be empty to change the valve.
Mike

[retired wrench]

I didnt catch the fact that the pilot stays on OK. That would indicate that the thermo is operating as it should. Had a house furnace that acted like this while the other gas appliences worked fine. Turned out to be a stuck regulator. RW

[mla2ofus]

I understood the pilot went out when the main burner went out. Didn't think there could be a problem w/ the thermo, but they don't cost that much compared to a gas valve.
Mike

[naylorchic]

Where can I order the parts? Thx again!

[naylorchic]

Oh & if it is a stuck regulator how do you "unstick" it? Do you have to change it?

[mla2ofus]

Google "RV parts". Have make, model & s/n of water heater ready. Check price W/ shipping charges against your local RV dealer prices. A lot of internet businesses make their money on shipping.
I think RW was referring to regulator inside the gas control valve. Maybe he will answer your question.
Mike

[retired wrench]

The regulator I was referring to was outside the house, on an RV it would be at the tank. I got this one to work by smacking it with a pipe wrench till it could be changed the next day. RW

[naylorchic]

Well thanks for your help. As soon as I find out what it is I'll let ya know.