Pressure Dropping In Boiler

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Old 01-07-13, 06:41 PM
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Pressure Dropping In Boiler

I just purchased a foreclosed home that has a Weil McLain hot water boiler system in it. I had someone come out and fire up the system on Saturday. I noticed yesterday that the pressure was around 10 and today it appears to be about 9.

I know absolutely nothing about these systems. Is it safe to add a little bit of water to bring the pressure up, or do I need to turn off the boiler and allow it to cool before adding water?

Is there a possibility that bleeding air would bring the PSI back up? I haven't opened any bleed valves since Sat and was told that I might have to bleed here and there over the next few days.

Anything else I should try to bring the pressure back to 12?
 
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Old 01-07-13, 07:26 PM
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I noticed yesterday that the pressure was around 10 and today it appears to be about 9.
At what TEMPERATURE are you seeing this low of a pressure?

Is it safe to add a little bit of water to bring the pressure up, or do I need to turn off the boiler and allow it to cool before adding water?
It depends on just how hot the boiler is and how much water you are adding.

In general, the small amount of water you will need to add won't hurt anything.

Is there a possibility that bleeding air would bring the PSI back up?
No chance at all. Remove air, remove volume in the system, and the pressure will go DOWN.

Anything else I should try to bring the pressure back to 12?
The only way to bring up the pressure is to add water.

====================================

Did you happen to notice if the guy checked the air charge in the expansion tank?

Is your expansion tank the type that looks like a gas grill propane tank, or is it a large steel tank strapped into the joists above the boiler?

Read these:

http://www.doityourself.com/forum/bo...ure-gauge.html

http://www.doityourself.com/forum/bo...sion-tank.html
 
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Old 01-07-13, 07:48 PM
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Thanks a lot for the reply. I'm actually not living at the house yet, so I don't know the exact temp on the boiler but I do know it was low (maybe 130ish). Will the pressure drop with the boiler temp? I thought I noticed the pressure tick up VERY slightly yesterday when the boiler fired.

The house is perfectly warm, right where the thermostat is set and the upstairs radiators seem to be operating fine. That's why I was wondering if maybe the pressure falls until the boiler fires? Thanks
 
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Old 01-07-13, 07:57 PM
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Will the pressure drop with the boiler temp?... wondering if maybe the pressure falls until the boiler fires?
Yes it will, but should only to a minimum.

In a typical 2 story home, you need at least 12 PSI when the boiler is cold.

When heated to high limit (which is probably 180F) the pressure might rise as much as 10 PSI, the exact amount depends on the size of expansion tank that is installed.
 
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