I have a closed hydronic loop with no obvious leaks in a boiler
heating system. The expansion tank is quite old. Lately I noticed the
pressure dropping even when the circulator is not circulating. What
starts out at 15 psi will be down to 7 by the end of the day. There
are no known leaks anywhere in the piping.
While the expansion tank seems to be the culprit by a process of
elimination, some signs point otherwise. For example, when I let water
into the system the gauge rises slowly as if the bladder is expanding.
Also the top of the tank is warm (when the therm calls for heat) and
the bottom seems cold which suggests the bladder isn't leaking..
Before I replace the tank, could someone give me their thoughts
on this? I sincerely appreciate your help.
Thanks.
Frank

The pressure will change a bit, as the system warms and
cools. The expansion tank is supposed to compensate for
expansion and contraction of the water. Makes me wonder if
the fill valve is set to 7 PSIG, and the 15 PSIG is when the
water is expanded.

On the system at my Dad's house, he has to drain the water
out of the expansion tank, every year. Takes a long time
(hour or so) for the air to bubble up in, and the water to
drain out. I'd try draining the expansion tank, if possible,
first.

Some expansion tanks have an air fill "valve stem".

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"frank1492" wrote in message
...
I have a closed hydronic loop with no obvious leaks in a
boiler
heating system. The expansion tank is quite old. Lately I
noticed the
pressure dropping even when the circulator is not
circulating. What
starts out at 15 psi will be down to 7 by the end of the
day. There
are no known leaks anywhere in the piping.
While the expansion tank seems to be the culprit by a
process of
elimination, some signs point otherwise. For example, when I
let water
into the system the gauge rises slowly as if the bladder is
expanding.
Also the top of the tank is warm (when the therm calls for
heat) and
the bottom seems cold which suggests the bladder isn't
leaking..
Before I replace the tank, could someone give me their
thoughts
on this? I sincerely appreciate your help.
Thanks.
Frank

Would you expect an increase of 8 psig due to expansion? I haven't
observed this for awhile, so you could be right.
I'll try draining the tank anyway. Thank you.




On Tue, 25 Oct 2011 19:45:37 -0400, "Stormin Mormon"
wrote:

The pressure will change a bit, as the system warms and
cools. The expansion tank is supposed to compensate for
expansion and contraction of the water. Makes me wonder if
the fill valve is set to 7 PSIG, and the 15 PSIG is when the
water is expanded.

On the system at my Dad's house, he has to drain the water
out of the expansion tank, every year. Takes a long time
(hour or so) for the air to bubble up in, and the water to
drain out. I'd try draining the expansion tank, if possible,
first.

Some expansion tanks have an air fill "valve stem".

On Tue, 25 Oct 2011 19:45:37 -0400, "Stormin Mormon"
wrote:

On the system at my Dad's house, he has to drain the water
out of the expansion tank, every year. Takes a long time
(hour or so) for the air to bubble up in, and the water to
drain out. I'd try draining the expansion tank, if possible,
first.

Some expansion tanks have an air fill "valve stem".

That sounds like the tank on a RO system under the kitchen sink.

They get "waterlogged" and need to be drained. Has the stem and the
baffle is not working once saturated with water.

On Oct 26, 12:11*am, frank1492 wrote:
I have a closed hydronic loop with no obvious leaks in a boiler
heating system. The expansion tank is quite old. Lately I noticed the
pressure dropping even when the circulator is not circulating. What
starts out at 15 psi will be down to 7 by the end of the day. There
are no known leaks anywhere in the piping.
* * *While the expansion tank seems to be the culprit by a process of
elimination, some signs point otherwise. For example, when I let water
into the system the gauge rises slowly as if the bladder is expanding.
Also the top of the tank is warm (when the therm calls for heat) and
the bottom seems cold which suggests the bladder isn't leaking..
* * *Before I replace the tank, could someone give me their thoughts
on this? I sincerely appreciate your help.
* * *Thanks.
* * * * * Frank

Well the water is going somewhere. There will be a pressure relief/
safety valve somewhere. Put a container under the outlet and see if
any water appears. It could be going to the air side of your
expension tank through leak in diaphragm but this will fill up
eventually & then the safety valve will dribble on heat up.

Remove the expansion tank and pour away the water on the wet side and
give it a shake. If there is water on the "dry" side, you will feel it
sloshing about & then you obviously need a new one. (Diaphragm has
hole in it.)

If you have pipes buried in concrete flooring you may have a hidden
leak there.

On Oct 26, 12:11*am, frank1492 wrote:
I have a closed hydronic loop with no obvious leaks in a boiler
heating system. The expansion tank is quite old. Lately I noticed the
pressure dropping even when the circulator is not circulating. What
starts out at 15 psi will be down to 7 by the end of the day. There
are no known leaks anywhere in the piping.
* * *While the expansion tank seems to be the culprit by a process of
elimination, some signs point otherwise. For example, when I let water
into the system the gauge rises slowly as if the bladder is expanding.
Also the top of the tank is warm (when the therm calls for heat) and
the bottom seems cold which suggests the bladder isn't leaking..
* * *Before I replace the tank, could someone give me their thoughts
on this? I sincerely appreciate your help.
* * *Thanks.
* * * * * Frank

The other possibilities are that the leak is inside the boiler. Hard
to check except by pressure test.
Or on the heat exchanger on your domestic hot water system tank (if
your hot water is derived from the heating system boiler)

frank1492 wrote in
:

I have a closed hydronic loop with no obvious leaks in a boiler
heating system. The expansion tank is quite old. Lately I noticed the
pressure dropping even when the circulator is not circulating. What
starts out at 15 psi will be down to 7 by the end of the day. There
are no known leaks anywhere in the piping.
While the expansion tank seems to be the culprit by a process of
elimination, some signs point otherwise. For example, when I let water
into the system the gauge rises slowly as if the bladder is expanding.
Also the top of the tank is warm (when the therm calls for heat) and
the bottom seems cold which suggests the bladder isn't leaking..
Before I replace the tank, could someone give me their thoughts
on this? I sincerely appreciate your help.
Thanks.
Frank


We searced for such a leak for 2-3 weeks.
Turned out to be inside the unit, leaking into
the condensate dump pipe.

You guys will have a laugh over my stupidity. One of the baseboard
bleed valves was leaking. It was running down the pipe into the dirt
cellar, but I didn't notice because somehow it wasn't draining onto
the floor.
Some good ideas from all of you. I'll make a list of them for
next time.
Thanks again.
Frank

On Wed, 26 Oct 2011 18:52:47 -0400, frank1492
wrote:

You guys will have a laugh over my stupidity. One of the baseboard
bleed valves was leaking. It was running down the pipe into the dirt
cellar, but I didn't notice because somehow it wasn't draining onto
the floor.
Some good ideas from all of you. I'll make a list of them for
next time.
Thanks again.
Frank

Good for you. Sometimes the answer is in front of the tip of your
nose.

Thanks for the follow up. No laughing, here. Just sharing
wisdom with another worker.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"frank1492" wrote in message
...
You guys will have a laugh over my stupidity. One of the
baseboard
bleed valves was leaking. It was running down the pipe into
the dirt
cellar, but I didn't notice because somehow it wasn't
draining onto
the floor.
Some good ideas from all of you. I'll make a list of
them for
next time.
Thanks again.
Frank

On Oct 26, 11:52*pm, frank1492 wrote:
You guys will have a laugh over my stupidity. One of the baseboard
bleed valves was leaking. It was running down the pipe into the dirt
cellar, but I didn't notice because somehow it wasn't draining onto
the floor.
* * *Some good ideas from all of you. I'll make a list of them for
next time.
* * *Thanks again.
* * * * * Frank

Ah well. Easy enough to fix anyway :-)

frank1492 posted for all of us...


You guys will have a laugh over my stupidity. One of the baseboard
bleed valves was leaking. It was running down the pipe into the dirt
cellar, but I didn't notice because somehow it wasn't draining onto
the floor.
Some good ideas from all of you. I'll make a list of them for
next time.
Thanks again.
Frank

You are NOT stupid! Extra points for posting what the problem was!

Thank you.

--
Tekkie