In your picture it looks more like the leak is below the brass nut, (in
fact you said this). I suspect the aluminum tubing may be porous due to
corrosion. I would get a suitable length of copper tubing and a tubing
bender - a device that looks like a spring that you slide over the
tubing to prevent kinking when you bend it. I would also buy 2
conventional compression tubing fittings for the tubing of that size
(probabaly 1/4 ").
I found that with a propane burner that I'm working on I could use the
ferrules from the conventional fittings with the nuts from the pilot
tubing and get a tight fit.
Engineman


Don Foreman wrote:
On Mon, 19 Dec 2005 08:59:31 -0800, Abrasha
wrote:

I am repairing a wall mounted gas heater. These are often found in
hallways of many apartments in San Francisco, and probably in many other
parts of the country as well.

The pilot light would not stay lit, so my first thought was to take a
look at the thermocouple. It looked old and worn, so I replaced it.

After reassembling the heater and lighting the pilot light, it stayed
lit without a problem and the heater worked again as it should.

Unfortunately, it was not just the pilot light that stayed lit. Gas was
also burning through a small leak below the brass nut (at red arrow in
bottom picture at http://www.abrasha.com/misc/heater_536.htm) that
attaches the "pilot tube" to the pilot light assembly. The pilot tube
connects the gas valve to the pilot light assembly. (see top picture)

I took the tube off, to see if there was dirt in there that prevented a
good seal. No dirt. However, the small brass fitting, that sits inside
the nut when attached properly,around the top of the aluminum tube is
looses around the tube on that end of the tube. I reattached the tube
and tested with soapy water (see bottom image at
http://www.abrasha.com/misc/heater_536.htm). Leak is still there, as
witnessed by soap bubbles. Obviously I need to replace the tube.

I now have trouble locating a replacement pilot tube. Does anyone know
where I might be able to get one around San Francisco?

Any leads appreciated.

That looks like a compression fitting, not a flare, particularly since
you mention a small brass fitting inside. If it looks like a little
brass ring with tapered front and back, it's a compression fitting.
Not a good choice for gas, particularly with aluminum tubing, but if
that's what you have, then you're stuck with it.

Get a new brass ring at the hardware store. Cut about 1/2" off the
end of the tube with a tubing cutter, install the threaded part and
then the brass ring, reassemble and torque it just until it quits
leaking.

The old one may have necked down the tube by overtorquing. Cutting
off a bit of the tube should take care of that.