rv furnace pilot light and thermocuople.

[MtnDon]

In our cabin wall heater and propane range oven the thermocouple end is in the flame.

[tony.latham]

In our cabin wall heater and propane range oven the thermocouple end is in the flame.

Yep: IN the flame. ACE should have a variety of thermocouplers.

TL

[pchast]

The only ones I've seen were in the tip of the pilot flame.

[Redneck Teepee]

Slow, simply explained, a therm-a-couple is a sealed tube of liquid with a known expansion rate. It has a larger, or bulb end that goes directly into and above the pilot flame for heat, with the other end into your gas valve pilot light port. Let's just say for simplicity, on the valve end of the tube that screws into the valve, it has a little piston that pushes out and opens the pilot gas port, and keeps it open as long as it has a flame to keep the liquid expanded, there fore keeping the pilot lit. If the flame dies, the liquid cools and retracts/shrinks closing the pilot port for safety reasons. Hope this shows you where to look.

[48Rob]

where is the thermocuple in a furnace supposed to be to get the pilot light to stay lit? how close to the flame should the thermocuple be. should it be in the flame or beside it?

The last 1/3 (the tip of the thermocouple) should be engulfed in the flame.

[warnmar10]

Slow, simply explained, a therm-a-couple is a sealed tube of liquid with a known expansion rate. It has a larger, or bulb end that goes directly into and above the pilot flame for heat, with the other end into your gas valve pilot light port. Let's just say for simplicity, on the valve end of the tube that screws into the valve, it has a little piston that pushes out and opens the pilot gas port, and keeps it open as long as it has a flame to keep the liquid expanded, there fore keeping the pilot lit. If the flame dies, the liquid cools and retracts/shrinks closing the pilot port for safety reasons. Hope this shows you where to look.

Are you certain of this? I think you're describing a thermometer not a thermocouple. A thermocouple generates a tiny electric current that is used to hold a gas valve coil open. The net result is the same; pilot goes out, gas turns off.

[pchast]

Its the correct term in talking about this capillary that controls the gas
valve on a gas furnace. Yes, your application, Electronics, uses the same
term.

Confusing isn't it...

[warnmar10]

Its the correct term in talking about this capillary that controls the gas
valve on a gas furnace. Yes, your application, Electronics, uses the same
term.

Confusing isn't it...

Maybe it's a regional thing. Around here, thermocouple only means: [A] device consisting of two dissimilar conductors that contact each other at one or more spots. It produces a voltage when the temperature of one of the spots differs from the reference temperature at other parts of the circuit.
We use them on gas fired water heaters, old fashioned gas furnaces, space heaters... pretty much anywhere a standing pilot is called for and no external power supply is available.

[rowerwet]

Not sure where you are, but I can go to my local home depot and buy a thermocouple ( says so on the package) that uses the fluid inside to keep the valve open. I doubt that is very regional as it is sold for gas water heaters everywhere.

[warnmar10]

Not sure where you are, but I can go to my local home depot and buy a thermocouple ( says so on the package) that uses the fluid inside to keep the valve open. I doubt that is very regional as it is sold for gas water heaters everywhere.

I'm in North Texas/Dallas area. Here's what we call a thermocouple in these parts: http://www.homedepot.com/s/thermocouple?NCNI-5

[Redneck Teepee]

Well sorry for any confusion on the therm o couple guy's, after reading the reply's I started goggling these things.

I would say that the common therm o couple for the home water heater is controlled by electrical created current, how ever my bad for assuming that a home water heater safety shutoff would have the same basic principle of operation of which I have no experience other than.... I own one. ....My background is in Industrial boilers, food processing/drying equipment, ammonia refrigeration, etc in which we used capillary filled safety valves and temperature controllers and sometimes even bellows controlled sensors for safety.

Did not mean to mislead, I just assumed that the actual operating principles were the same.

[PaulS]

I have ran acrossed both types of thermocouples electrical and mechanical that is a capillary tube with Mercury. The electrical ones generate a small amount of electricity when heated. I have found theses on industrial tempature controllers and I once had a gravity fed furnace ( a big octopus looking thing ) that used this ( kind of nice it worked even when the power went out). The mechanical kind I have found on water heaters, and forced air furnaces. As to how much flame should touch the thermocouple. I Agee with the 1/3 theary. This is just my opinion

[pchast]

Its the correct term in talking about this capillary that controls the gas valve on a gas furnace. Yes, your application, Electronics, uses the same term.

Confusing isn't it...

Maybe it's a regional thing. Around here, thermocouple only means: [A] device consisting of two dissimilar conductors that contact each other at one or more spots. It produces a voltage when the temperature of one of the spots differs from the reference temperature at other parts of the circuit.
We use them on gas fired water heaters, old fashioned gas furnaces, space heaters... pretty much anywhere a standing pilot is called for and no external power supply is available.

Nope not regional. We have them too. Extensively used in the HVAC work I used to do here. Its just a different system/function. Those used in gas valve service were commonly filled with a freon. They were easy to destroy by kinking or poor leads, friction causing a worn in hole.

[MtnDon]

Yep, the thermocouple has to be in the pilot flame to be heated. I've been told that too much soot on the thermocouple can cause the pilot to go out. IF the thermocouple gets heated properly and the flame goes out it could be a bad thermocouple or a bad gas valve. Possibly even a bad regulator. If other appliances work off the regulator then it should be good.

[wagondude]

If the vent is getting too much wind, the pilot light can blow out, also. Probably not your problem, though. Just something to watch out for.