Pilot Light won't stay lit

[Mike Callaha]

Hi everyone.
I am a first time poster. I have an 84 Sovereign that I have been living in while I build my house. Recently the water heater has quit working. I replaced the thermocoupler and still it does not stay lit.
Is there a special thermocouple for this application? The control is an Atwood. Would it help to replace the control? Where is a good place in Northern California to buy Airstream Parts? Where is a good place to buy parts online?

MIke Callahan
Lake Tahoe

[TomW]

Hi Mike, and welcome to the Forums!

When you say "does not stay lit", do you mean it goes out after you release the red button, or does it stay lit only to go out a short time later?

Tom

[Tinsel Loaf]

Welcome to the forum.
The thermocouple provides a small current to an electromagnet that keeps the safety valve open. If the pilot flame is adjusted correctly (it should be next to the flame just touching it and not right in the middle of it) the thermocouple may be the wrong one for your heater. Most appliance parts stores should have your thermocouple, just take in the original one in and they will know what kind you need.

[Inland RV Center, In]

Thermocouples have a very small voltage output, called millivolts.

Different type thermocouples have different millivolt outputs.

Generally speaking, universal thermocouples don't have enough output for RV type appliances. Therefore they usually won't work satisfactorily.

Also, thermocouples must be installed and tightened down, "very" firmly. If not, it won't work at all.

Andy

[Gordon Watt]

Originally Posted by Mike Callaha

Hi everyone.
I am a first time poster. I have an 84 Sovereign that I have been living in while I build my house. Recently the water heater has quit working. I replaced the thermocoupler and still it does not stay lit.
Is there a special thermocouple for this application? The control is an Atwood. Would it help to replace the control? Where is a good place in Northern California to buy Airstream Parts? Where is a good place to buy parts online?

MIke Callahan
Lake Tahoe

I had to replace the gas controller on my water heater.

[eubank]

On our fridge, the tube above the flame had all sorts of rusty gook in it, and some of it landed right on top of the gas orfice, causing it just barely to run, or to be impossible to start in many cases. I removed the works and cleaned it. Presto.

Lynn

[Mike Callaha]

Thank you for the replies. I have been away for a few days.
I have tried the off the shelf thermocoupler from the local hardware store without success. Perhaps I do need a special RV thermocouple. I will try that before changing the control. Does anyone know the millivolt rating for an RV thermocoupler? I have (Duh) discarded the old thermocoupler.

Mike Callahan

[bryanl]

I had a problem with my water heater pilot light - weak flame and wouldn't stay lit.

I pulled the tube from the gas valve and noted that the gas valve would hiss when on thermocouple bypass. - I ended up cutting off the orifice on the tube and crimping it down to get a workaround for the weekend. It appears the pilot orifice had crudded up. I guess twenty years or so of service was enough for it.

I do not recommend the crimped tube orifice solution but at least it allowed me to get hot water over the weekend. The exercise also showed me that the thermocouple depends upon the pilot and not on the burner. I also found out the gas valve feeds enough to the pilot to make quite a burner in itself! I crimped the tube end enough to keep a pilot flame somewhat reasonable and the thermocouple hot while the burner was going. I ran it this way only when I needed hot water and then turned it off to avoid imagined or real problems from a rather hot pilot flame.

It appears that the pilot tube assembly can be had for about $20-$30 and includes the pilot orifice and the thermocouple. I have that on my 'priority to do' list!

[Inland RV Center, In]

Mike.

It's easy.

Get a thermocouple for the model furnace that you have.

Different models use different thermocouples.

Andy

[TomW]

Originally Posted by Inland RV Center, In

...Also, thermocouples must be installed and tightened down, "very" firmly. If not, it won't work at all...

Mike,

If the pilot light only remains lit when the red button is pushed, the problem is probably with your thermocouple. Its either bad, or improperly installed in either the controller or the flame. If the the pilot remains lit for any time after releasing the button, there are other factors working against you.

I personally do not subscribe to the "RV thermocouples have a higher output" theory. Its possible, but to me unlikely.

I do subscribe to Inland's comment above.

More details on your EXACT situation may enable Forum members to help you solve your problem.

Tom

[WayWard Wind]

Thermocouples do come in higher outputs & are called Pilot generators. They come in 250-500 & 750 millivots (generally speaking), as there are always exceptions. These kinds are used to generate enough current to open gas valves where electric is either not available or needed. This kind would be found quite often in the older small trailers heaters & not water heaters. For the most part a simple off the shelf thermocouple should work, however to make sure of the right installation needed, it is always best to take the old thermocouple along for a comparsion. Some of the older water heater thermostats had an internal high temp shut-off installed with-in the internal temp control probe & if the water heater over heated, it would interrupt the current flow & cause the heater to shut down. One can determine if your control has this function by looking at the red ring where the thermocouple attaches to the control & if there are two wires coming into the control, these would be coming from the internal high temp shut down. If the heater shuts down from hi-temp then the control would need to be replaced. It appears that either your thermocouple or control is bad. If in doubt have the heater checked by a qualified tech.
Best,

[TomW]

Originally Posted by A.E. Milliman

Thermocouples do come in higher outputs...

You are quite right. It is a question of dissimilar material choice in the design of the thermocouple.

However, are the kicked-up ones commonly installed in RV applications? They may well be, but I would like to know why.

Tom

[WayWard Wind]

TC ---generally no ---they might be found in the earlier models ( 50's-60's)when TT & moblie homes used what the market called free standing heaters.They usually will differ from standard thermocouples in that they had 2-spade ends instead of the nut that are found on a standard thermocouple. They also are quite a bit larger around on the the pilot end. This of course was so they could generate a larger amount of millivolts.
Best,

[diesel]

Many thermocouples are made of aluminum and over time build up a high resistance where they are connected into the system via a different metal socket. A long time ago I learned to first suspect this condition, remove and clean the threads, and use a liberal amount of dielectric grease when reinstalling.

This was the same condition that caused all those fires when aluminum wiring was used via dissimilar metal connectors in open air. Although there isn't enough current induced by the piezoelectronics to cause a fire, enough resistance can build up to reduce the current thus closing the gas safety valve.

[Mike76251]

I had the same problem and found the ECO had shot.
Mine is a Atwood gas/electric 10 gal model and the first time I used both 120v and gas at the same time the ECO blew.
I called Atwood and asked if there was a higher temp rated ECO avalible and they,of course, said send the water heater back in or take it to a dealer.
Their stance is "make as much as you can off the consumer".
If I had done what they said I would have been out $150+ and the darn ECO would just blow again as soon as I used the 120/gas combo 'cause they only make them to blow at 180 degrees plus or minus 20 DEGREES.

Flame me or not........I bypassed the thing and it has been working great for 5 years..........after all it does have a pressure valve on it.

[Mike Callaha]

Hi
I am back again and I am pleased to say that my pilot light will now stay lit. Thank you all for your help and suggestions. I have not been living in the trailor because I moved into my new house. I winterized the trailor and forgot about it for a few months except for when I had to remove snow off it. Thank God for the Snow Hoe.
I replaced the whole assembly including the thermocouple and pilot supply tubing from Atwood. That did the trick. I am glad that I didn't have to replace the control. That would have been a pain. It seems that the pilot supply has a microscopic pinhole that gets clogged after a while. It cost me about 23 dollars and two trips to Reno.

Mike