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ErikKratz 07-10-2008 10:13 AM

How to keep attic pipes from freezing in winter with gable vents
I just bough my first home. It is a 1950's ranch on a slab foundation. Because it's on a slab, all the piping is in the attic. The problem I'm having is that the pipes are freezing in the winter because the attic has gable vents that are letting all the cold air in. I've had to keep the door to the attic open when it gets really cold to keep them from freezing which I'm sure is costing me a lot of money in lost heat. Any suggestions on how I can keep the attic at a somewhat reasonable temperature while retaining the required ventilation? I've tried insulating the pipes, but that didn't seem to provide enough protection. Thanks in advance for any advice anyone can offer.

BillyD 07-10-2008 10:53 AM

Get some heat tapes and wrap your pipes. Also can you put covers over vents in the winter?

ErikKratz 07-10-2008 11:05 AM

I've had heat tape mentioned to me before, but have been hesitant to put anything involving electric heat in the attic for risk of fire. As for covering them up, I could easily do that, but was under the impression that blocking the ventilation in winter would lead to moisture issues.

geo fan 07-10-2008 03:11 PM

are the pipes for the heating system or your drinking water, are the pipes insulated they now sell pipe insulation with a 1 inch wall. If they are domestic water tear out the copper and put in pex it is plastic and can expand 50% of its size . and insulate you may have to sacrifice some closet space for a header to distribute the line because tee's and couplings in the attic will give a weak spot. If its heating pipes add antifreeze to you heating system in a 50 /50 mixture they also have anti-freeze switches that will turn your heat on for a few seconds to heat the pipes when the get close to freezing. Do not block the vent's this will make it colder . I know it seems counter intueative but its true just as your attic is hotter then the outside in the summer its colder in the winter , can explain or in a few months test with a thermometer

8 Ball 07-11-2008 05:29 AM

If your pipng is underneath 12 in. of insulation, in your attic, I cant imagine why they would still freeze.

Try posting your question in the plumbing section. Theres some pretty crafty dudes over there, and I would like to know the answer.

I would appreciate an explanation of how the attic gets colder than the outside during the winter. Summer I can understand, but Im having trouble with the winter thing.

geo fan 07-11-2008 03:32 PM

Beleive it or not
The decreased sun exposure to the roof ( snow and shorter days) the reason attics are so much hotter in the summer then outside is because the sun hitting the roof for periods of time to the point where the roof is much hotter then then the outside then the outside air this heat is then conducted into the attic. the temp differences are such that this a large amount of heat. In the winter the sun will also heat the roof but it is much less signigicant , there will only be a few degree difference between the roof and the outside air. this means much less of the heat is conducted through the roof and is simply lost to the outside. So on sunny days the attic has more of the shade effect then the attic effect at night the temps even out if ventelated if there is snow on the roof you be lucky to over come this , the snow obvously reflecting all the sun. this is not true if your cieling is not well insulating where you will be gaining heat from the living space or if you leave your attic access open. Next time you go up in the winter take temp readings it actualy pretty cool (fact not temp)

Yoyizit 07-11-2008 04:09 PM

to keep attic pipes
Where the pipes are now need to be part of your living space, thermally speaking.

You could
Make an enclosure over the pipes, and
remove the insulation under the pipes and this enclosure, and
put that removed insulation over the enclosure.

The principle is the same as when you open kitchen cabinet doors on cold winter nights to prevent the kitchen pipes [which are next to an outside wall] from freezing.
Doors open = cabinet insides now part of your heated living space.

If you don't like NEC-compliant electricity in your attic, use a heated tape [mentioned already] but powered by a low-voltage xformer, with the xformer being fused.
Additional safety can be had with thermal overtemperature sensors but they may already have this to get UL approval.
The likelihood of a fire caused by this type of properly installed low voltage setup = ~0.00.

tribe_fan 07-11-2008 09:32 PM

I'm not a pro plumber - but I do have a slab house with pipes in the attic.

Wrap the pipes in it the black wrap-around stuff with the split in the middle.

Put the house insulation OVER the pipes.

Plan B:

Buy a remote thermometer on monitor the temperature.

Realize that at a certain temperature - just trickle the water in a remote faucet.

If you do decide to use heat tape - (and it does work) consider something that is thermostatically controlled. They really cost a lot to run.

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