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
They make heat tape to prevent freezing pipes. Buy some, wrap it around
the trap, and plug it in on cold nights. Changing from a metal trap to a
less heat conductive trap made from PVC might also work. I'm not sure that
heat tape is safe with PVC pipe.
On a pedestal sink Joseph?
That's about as helpful as my suggesting to him that he leaves a small
stream of hot water running all night. <G>
Speaking of freezing things:
Assuming that the majority of the cold air isn't coming down the vent and
that you have already isolated the metal vent pipe from the metal P-trap,
I have a very similar problem today; I thought I was doing the right
thing using the slow drip method to not have pipes freeze, but I now
have a leak from the end of the P trap. I'm wondering if I should try
to put hot water in the sink and if breaking up that ice will ease the
pressure on where the trap meets the next pipe.
Is it typical for water to stay standing in the P trap? I would guess
so, lots of rookie questions I have here.
Don't mean to hijack this thread, just joining in on the fun <g>.
Yes, it's normal for water to stay in the P trap. That's what it's
for. If this is an ongoing problem, one half-assed solution is to
keep a gallon of RV antifreeze nearby, and pour about 8 oz down the
drain on cold nights, after you're done with everything else.
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