Hot Water Boiler preasure drop on really cold days


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Old 03-05-12, 09:14 AM
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Hot Water Boiler preasure drop on really cold days

I have what I believe is an interesting issue.

This winter (since I have owned the house anyway) we've had 4 decent snow falls (day temp ~ -5'C) followed by a good cold day (-25'C or colder). We've had snow on other days and some good cold ones, but I only noticed this issue when we went from mild to good and cold.
On the mild days, the preasure stays about normal (~20PSI), but then when we get nailed with the cold, it drops down to ~10PSI and I have to add some water to the system (suspect my system is not setup to add as needed, or is broken).

Does this sound normal?
I can see maybe a bit of a drop due to the higher demand, but that is a fair drop.
 
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Old 03-05-12, 01:09 PM
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Hello Mike,
Are there large area's of the house that are not fully heated?

In my house, i'm not using the third floor much these days.
It's usually mid to high 60's up there, but if it gets really really cold, it might drop to the high 50's,
Something like this might make the water in your system compress due to the cold.


However, i'm afraid it sounds like when the boiler is stressed and working hard, there might be a leak(s) somewhere in your system.

Peter
 
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Old 03-05-12, 05:00 PM
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Mike, it's important to ALSO note the boiler TEMPERATURE at any particular pressure reading.
 
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Old 03-06-12, 06:19 AM
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Originally Posted by PeterNH
Hello Mike,
Are there large area's of the house that are not fully heated?

In my house, i'm not using the third floor much these days.
It's usually mid to high 60's up there, but if it gets really really cold, it might drop to the high 50's,
Something like this might make the water in your system compress due to the cold.


However, i'm afraid it sounds like when the boiler is stressed and working hard, there might be a leak(s) somewhere in your system.

Peter
My third floor sounds the same as yours.
It is part of my second floor zone, but is only one room, with a single rad. It's cooler then the rest of the house (assuming the insulation isn't great). The room is totally isolated from the rest of the warm areas. It's in the attic with ~10" of blow-in below it's floor and two doors (room door and one at the bottom of the stairs).
I suspect that because it is the coldest room, at the highest point, that it could be the trouble spot. It's also newer construction from the rest of the house so I think it may have been an addition to the heating system after it was originally installed. (The house is mostly old 1930's plaster, but this room is drywall and newer hardwood floor).

I think that rad has (like the rest) it's own t-stat on the pipe which is wide open like the others. We aren't using the room so I might close it off and let it go cold.

Originally Posted by NJ Trooper
Mike, it's important to ALSO note the boiler TEMPERATURE at any particular pressure reading.
Unfortunately I wasn't really keeping tabs on that (mentally remembering the temp ranges).
I'll keep an eye on it.
 
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Old 03-06-12, 02:08 PM
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The pressure drop

Are they regular rads or baseboards? If regular rads, are you shure that there is flow in and out of the rad? Do you have a way to bleed possible air from that rad? Is your expansion tank working? Can you see all of your heating pipeing, to check for leaks? Is there more than one zone? If it is baseboard, do you have a way to bled air at the highest point of your system?
Sid
 
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Old 03-12-12, 04:51 AM
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Originally Posted by sidny
Are they regular rads or baseboards? If regular rads, are you shure that there is flow in and out of the rad? Do you have a way to bleed possible air from that rad? Is your expansion tank working? Can you see all of your heating pipeing, to check for leaks? Is there more than one zone? If it is baseboard, do you have a way to bled air at the highest point of your system?
Sid
I am running two zones, which covers 3 floors (zone1 = main floor, zone2= second and third floor).
The entire system is baseboard style rads and I do check for air regularly (bleed screw on all rads, a couple have their screw heads broken off. I moved into the house during this winter and because of my work schedule, haven't been able to shut down the boiler to replace the broken bleed screws.)
I do have one spot right at the circulating pump that drips a drop every 30-45 seconds, but as previously mentioned, I haven't been able to shut it down to repair. The rest of the system is dry from what I can see. The entire main floor loop is visable and I have checked the second zone in a few spots (runs through the crawl space between the first and second floor, which is ~12' above the floor).
 
 

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