What if two thermocouples want to live together, but not be married. Would
that be commonlaw coaxial cohabitation? That's a conundrum. Do you concur?
Christopher A. Young
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That could make for a good TV show. The two thermoucopules of Detroit,
Christopher A. Young
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On Saturday, February 9, 2013 4:52:45 PM UTC-6, Stormin Mormon wrote:
2 couples would be 4 people...that would just be wrong! Start thinking
outside-the-box and not with you head in it.
Now I see that the 1/8" copper line that has a 3/8" nut is the thermocouple.
The other 1/8" copper line has a 5/16" nut holding it to the valve body.
Upon closer inspection, I find that it is a copper tube that is open
on the end. About 2 1/4" from the open end, there is a 3/16" OD brass
The ferrule can't be slid on the tubing easily. There is a clamp on the
outside of the metal pilot box that looks like it could hold the tube in
place, but the clamp is loose, and it was not holding the tube, not
What is the function of this open-end tube, and how should the end be
situated when I reassemble it?
BTW I am in the Midwest, and the input rating is 110,000 Btu/hr. The
aluminum pilot tube was replaced a couple years ago at a cost of about
$100 when it did not need it. I am assuming that the reassembly was
Look for a part number on the gas valve, cross reference that with
your furnace model number, and search the internet.
Some here might do the search for you if you provide the numbers.
Otherwise, it's just shooting in the dark - and maybe dangerous.
There's lots of gas valves and different setups.
Okay, I looked closer at the valve, and the open-ended copper tube is
attached to a port on the valve marked "VENT".
What is the purpose of that vent?
The valve bears the number B57RB67. It seems that perhaps it can be
replaced by Robertshaw 720-402.
The "vent" is to vent any gas that might leak from the valve
assembly to the pilot where it will burn harmlessly -and in normal use
apply atmospheric pressure to the atmospheric side of the regulator
(if so equipped)
On 02/09/2013 05:53 PM, firstname.lastname@example.org wrote:
Yeah, good. Okay thanks, Vic and Clare.
I'm ready to go ahead with the replacement of the thermocouple now.
And now it seems that the last guy to work on this didn't get the vent
properly situated in the pilot flame.
Also I will be shutting off gas to the furnace from June 1 to October 1
Thanks for all of the helpful replies.
First of all, your furnace sounds very old having a pilot with low
efficiency. And pardon me, looks like you haven't got a clue what you
are upto. Often there is a adj. screw under a plug on the valve body for
pilot flame size and if the thermocouple connection is tight, just re-
place it. And adj. pilot flame size proper - Done.
OP said click and pilot goes out after couple mins. TC output drops and
gas supply to pilot quits. Replace the damn TC which is
not really expensive. Some more thought? Pilot flame positioned wrong,
chimney draft? What else is left?
> On 02/08/2013 09:26 PM, themattfella wrote:-
My understanding is that old gas valves had "vents" which vented small
quantities of gas into the pilot light. However, if your pilot light
assembly has been replaced in the past 20 years, you probably won't have
anywhere to connect that vent line to.
I can't see what you have there, or how it's all supposed to fit
together, but you need to put things back together so that the end
result is that anything coming out the end of that vent tube gets burned
in the pilot light. You might even have to hold things together with
some bare copper electrical wire or the steel wire in twist ties to
accomplish that, but looks don't matter. As long as you burn any gas
that comes out of that vent tube, that's all that matters.
Okay, yes, thanks, I understand that.
Now I do have one practical question remaining.
If I situate the open end of the vent tube in the flame of the pilot,
will the tube suffer oxidation that would eventually cause a problem?
I imagine: 1) a crusty green growth blocking the opening, or 2) the end
of the tube being eaten away by the flame.
Again, the vent tube is 1/8" OD copper tubing.
On 02/10/2013 04:08 PM, email@example.com wrote:
I completed the repair some hours ago. Thanks to all who contributed to
I was wrong about the vent tube being copper. It is steel. I
positioned its end about 1/8" below the flame of the pilot. I hope that
that is far enough away. If not, please explain, and I can move it.
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