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Old 10-10-2008, 07:39 PM   #1
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too High boiler pressure


I drained my gas hot water boiler to move some baseboard and when I restarted the system the pressure has gone to 45# and only 2 out of three zones are working. The pressure should be around 20 or 25
I need suggestions to try to fix this problem

There is a valve stem on the bottom of the expansion tank so I wonder if the air in the expansion tank should be released to lower the boiler pressure.

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Old 10-10-2008, 10:24 PM   #2
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too High boiler pressure


Hey beacu,

You said you moved baseboard, so some of this may be stating the obvious as you clearly have some plumbing knowledge... but I thought I'd throw in everything I thought of..

Quote:
I drained my gas hot water boiler to move some baseboard and when I restarted the system the pressure has gone to 45# and only 2 out of three zones are working.
Is 45# the static pressure (when the boiler is shut off), or does it shoot up to 45 only when firing?

Did you bleed air from your system before firing it up?

There are 2 things that should be regulating your pressure: a feed regulator valve (keeps the system topped off from your water supply), and a pressure relief valve.

If you don't have a regulator valve, did you have to manually open a valve to recharge the system after you added the new baseboard? And more importantly, did you close that when it was filled? It's possible you have roughly water main pressure in the system -- you may just need to trigger the pressure relief valve to ease up the pressure.

Most pressure relief valves would be set (or come pre-set) at 30# for a HW boiler like yours, and so it should be doing its thing and releasing water with your system at 45#. You should check yours b/c keeping your system overpressured can be damaging. (It can be manually operated with the lever at the top -- but do this with a bucket underneath the discharge and when the boiler is cool to avoid burning yourself).

Quote:
The pressure should be around 20 or 25
20 or 25 actually sounds a bit high. Is that the reading you usually saw, or is that the spec of the boiler?

Quote:
if the air in the expansion tank should be released to lower the boiler pressure.
You may need to do quite the opposite and remove water.. check this out, this link goes into detail:

http://homerepair.about.com/od/heati...t_boiler_5.htm

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Old 10-18-2008, 11:52 AM   #3
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too High boiler pressure


Thank you for replying. I really appreciate it..
I bled the air out, replaced a valve and thought that I had taken care of the problem but now I have hit something different... I have three thermostats with three zones and the problem now is that one thermostat works all three zones; no matter which thermostat is turned up all three zones come on and it is difficult to believe that all three would stick open at the same time.
Do you have any ideas why this would happen and what I could do about it?
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