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Posted by Derek on January 23, 2008 at 06:45:09:
In Reply to: Re: Burnham revolution boiler leaks through regulator valve posted by Oskar Bosch on January 22, 2008 at 19:35:27:
: : What does the pressure gauge read?
: : Does the pressure increase when the boiler is running?
: : The first suspect is the expansion tank.
: Derek, thanks for the quick reply.
: I had to install a new pressure gauge, as the one on the boiler is dead. Anyway, the pressure goes from 32lbs downto zero?
: I got a pressure gauge that reads up to 160, so it is kind of inaccurate in the lower range. But what seems to happen is that the pressure raises when the boiler is active (flames going). When the flames go out, the pressure slowly goes down. The zone keeps asking for heat though.
: So it seems an up-down-up-down movement (flames on - flames off - flames on - flames off) of the pressure.
: The pressure gauge was mounted on the return from the zone asking for heat.
: What puzzles me is how the system can keep leaking water, over 2 buckets by now, with the water inlet shutoff. So no new water is entering the system, yet it keeps loosing water.
The fill valve could be leaking by a little.
: Could this be air in the system? Is this the expansion tank?
If the system draws enough vacuum it is possible that the water is repalced by air.
You would definitely hear it.
Do you have a tank hanging near the boiler?
Newer ones generally are roughly the size of a small propane tank and have an air fitting on the bottom. Older ones are sometimes hung between the floor joists.
The expansion tank has an air bladder. The air compresses as the water temperature increases and system pressure builds. This keeps the water presure in the system from fluctuating too much. Mine runs at 12psi all of the time. If the bladder breaks the tank can fill with water thus rendering it useless to regulate the system pressure. This could why your pressure relief valve is dumping.
Replacing it requires shutting down the system and if there are no valves to isolate it, draining and refilling. Without seeing it I would recommend getting a technician to check it out.
Boiler water is hot and the job can turn into a nightmare if you are inexperienced with this kind of work.
Keep in mind this is only a guess but it is definitely the first thing to check.
If you have a tank with the air filler check the pressure when the system is at 0psi.
If water comes out then the tank is bad.