have you tried letting the water drip through the coldest nights?

"MPost" wrote in message
...
I have a bathroom sink that's against an outside wall. The vent for the
sink drain goes straight through the wall and then up outside the house to
the eaves. When it gets cold (single digits), the water in the P-trap
freezes into a solid plug and stops the sink from draining. I've put as
much insulation in as I can, but it still freezes when it gets bitterly
cold. Any ideas how I might be able to resolve this without re-routing the
vent line or boxing it in? I've thought about placing a small hot pad
around it or hanging a light bulb near by, but this is a guest bathroom and
it's a pedestal sink, so anything that I put around the P-trap itself would
be visible.