On Sun, 03 Feb 2008 15:14:35 -0000, Phil again
wrote:


[...]
I am going off on a tangent which may not have anything to do with your
problem, this is from my memory of living with a hot water heating system
a a bit more than a decade ago.

With my system, up in the rafters of the basement was a cylinder; it
looked about like a 10 gallon black metal cylinder. This, I was Told,
was an expansion tank for the hot water. My system was not rated for the
circulated hot water to build up pressure (county building code thing.)
Inside the tank was a rubber membrane, air on one side, and furnace water
on the other side of the membrane. On the air side of the tank, there
was a low point with an air bleed valve, to regulate the air pressure (or
vacuum in summer) caused by expanding / contracting hot water.

The pressure relief valve on the system, I was told, had a high temp /
pressure release point. I was told, IIRC, that if any water leaked from
the pressure relief valve to 1st open the air valve on the expansion tank
and release "some of the Air Pressure". (I put that in quotes, as I
didn't get specific air pressure instructions.) I was, however, given
explicit and specific instructions that when I opened the air valve, to
keep a hand under the valve to see if any water escaped with the air; a
sign the tank needs replacement.

With a "KA-CHING" in his eyes, the Hot Water Furnace guy told me the tank
replacement was not a homeowner type of thing. Later I remember having a
good hard look at the furnace pipe connecting to the tank, and the
bracing of the tank in the rafters, and mostly I agreed a job like that
should be left to someone else with more pipe soldering skills than I
will ever have. I just knew that I would most likely set one of the
rafters on fire.

Again, this is a bit off topic and may not apply to your local building
code.

Phil

Hi Phil,

I swear my ISP's news server is hooked-up to a crank telephone on a
party line, so I didn't see your post until after I had uploaded mine.
I think all of us are fingering this as the most likely cause and,
hopefully, the OP can drain some water and correct the problem without
encountering any out-of-pocket expense.

When I had my new boiler installed five years ago, they didn't bother
to replace the pressure relief tank and, in hindsight, I wonder if
that should have been done.

Mine is very similar to what you described. You can find a picture of
it he
http://www.datafilehost.com/download.php?file=06173172

Cheers,
Paul