crown boiler pressure problem

Old 01-30-12, 06:12 PM
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crown boiler pressure problem

Hey, i am new to this site so bear with me. i have a 6yr old crown oil fired boiler. Its 2 zone 2 story house 1st floor zone are radiators 2nd floor zone are baseboards. My pressure at 180* is at 30psi, i have blown down the boiler at the bottom at made sure my auto feeder is shutting down at about 11 or 12 psi, that seems to be working. i have the old steel exspansion tank in the floor joist with no iso valve only a valve to drain it. i drained it got about 2 to 3 gallons out of it, i did shut the valves that are on the feed and the return lines but i am not sure if all the water is coming out or i am pulling from the system pipes. i hope that is enough info., after i did all that it still runs atlike 30 psi, please help.
Old 01-30-12, 07:07 PM
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You say it's at 30 PSI... and that means that the relief valve is dumping, right? If not, there's a very good possibility that the pressure gauge is lying to you.

You should think about verifying the pressure gauge accuracy.

Here's a clip from a recent thread:

Please see post #20 in the thread below .
You need to get all the water out of the tank... if you close all the valves and can isolate the system from the boiler, AND shut off the valve that feed water into the system, you should be able to drain the tank without the isolation valve.

This is a piece of a reply to another recent thread... it's sorta relevant to your problem:

Possibly... gravity is the main culprit at work here. If you are able to totally isolate all the piping above the boiler to prevent it from draining back into the boiler, and shut the blue feed valve(s) you may be able to drain the tank without the water from above flowing back in. Study the valves and such...

Something else you should know about draining those tanks... I call it the 'drinking straw analogy'.

Place a finger over the drinking straw and lift it from the drink. The drink will stay in the straw. Same effect happens when you drain the expansion tank.

When you hook up a hose to the drain, some water will drain out of course... and then it will stop, causing you to think the tank is empty, and in most cases, it is NOT. There is a vacuum above in the tank that is preventing the rest of the water from draining.

The use of the largest and shortest length of hose helps. If the hose is looped all over the floor, you will never get the tank drained. Air needs to find it's way back into the tank. Often loosening the hose on the fitting will let air in. Sometimes you need to remove the hose and use a bucket under the drain. You will read about people saying to blow into the end of the hose... I don't recommend that. You can use that air compressor though... but whatever you need to do to get it drained is what you would need to do.

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