Freezing radiator pipe

Old 05-01-05, 03:23 PM
Rick Michel
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Question Freezing radiator pipe

In extremely cold weather one of our second floor radiators goes cold. The pipes to the radiator traverse an uninsulated external first floor wall and I'm pretty sure either the feed pipe or the drain is freezing. This is a 1920 era home with newer forced hot water boiler system. I am guessing originally hot water was always circulating and so the pipes never had a chance to freeze, but perhaps added attic insulation, and lower set temperatures allow the boiler to shut off long enough for the pipes to cool and freeze. It has happened twice since 1995. Can I add antifreeze to the boiler system? What is the best and/or least invasive way to insulate the pipes in the wall to keep them from freezing. Is there something else I should be doing?
Old 05-02-05, 11:10 AM
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Freezing Pipe

Boiler anti-freeze could be added to the system. DO NOT USE AUTOMOTIVE ANTI-FREEZE. Insulating a pipe in a wall can be a tough job. If you have room, you could slide foam pipe insulation up from the basement.
Old 05-04-05, 12:54 AM
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Freezing Supply Pipe

Rick Michel:

Grady makes sense; pipe freeze-ups are more common on the side of the house with the prevailing winds; usually, the freezing wind is blowing right on the exposed pipe itself due to loose-fitting siding/sheathing & little or no insulation.

The non-toxic antifreeze used in heating systems is known as propylene glycol & it works, but the problems with it are its cost at ~$8-$10/gallon, you would need a minimum of a 50/50 solution of antifreeze/water to get 0 degrees protection & 60/40 to get -16 degrees protection; if your system has ~15 gallons of water, that's ~$80; if the system has to be drained anytime in the future for service (not uncommon) you would have to add more antifreeze; it also tends to leak more if the joints are not absolutely tight.

Anther option would be to look at leaving the current pipe where it is & running a new supply pipe thru an interior wall, or even box it in along the present interior wall with plywood or pine boards; this would be a permanent solution at low cost.

There are other options such as having insulation blown into the exterior wall in question by a contractor (it is done from the outside after removing a piece of siding here & there); this would pay for itself in a short time in saved fuel bills in winter & summer.

The circulator on the boiler could be wired to run constantly during cold weather & thus prevent a freeze-up; this would add a slight amount to your electric bill.

If it was my house, I'd opt for re-routing the pipe, if you have access; if rigid 3/4" copper pipe presents a routing problem, flexible copper tubing, or plastic PEX tubing is used as an alternative.

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