On 11/26/2013 3:23 PM, DerbyDad03 wrote:
Jon Danniken wrote:
On 11/25/2013 05:21 PM, DerbyDad03 wrote:
"bob" wrote:
During feezing weather, I like to leave a faucet dripping to reduce the
chances of freezing pipe. However, people including me sometimes forget
and turn off the faucet completely.

Is there a dedicated valve that can be installed under the sink to let a
trickle of water out and directly into the p trap? This way nobody sees
the dripping and cannot accidentally turn it off.

Real tough to tell if you are serious, but I'll play along...

Define "dripping" in terms of enough to prevent freezing.

Why are you concerned with this particular faucet freezing in the first
place?

There's lot of details that you should be sharing.

This is recommended up here in the PNW whenever we get a lengthy cold
snap (as we are getting now). The idea is that a little flow somewhere
in the house keeps the water moving, and prevents freezing/ruptured pipes.

Just read one such recommendation a few days ago, actually.

Never done it myself, and have never had any trouble (I do cover the
outside hose bib, however).

Jon

I am familiar with the concept that running water does not freeze.

You're sure about that?
Frozen water doesn't run...but that's confusing cause and effect.

Dripping the faucet has nothing to do with flow.
It's all about the thermodynamics of putting heat in faster than
it radiates to keep the temperature above freezing.
If you have a source of unfrozen water running at a rate that
gets it to the dripping faucet before radiation/conduction/convection
causes the water
to freeze at any point in the pipe you're good to go.

Dripping the bathroom faucet typically won't do much for the kitchen pipe.

Dripping is most effective when you have a short run of pipe that's
exposed to the cold, but the rest is much warmer.
If you have a quick response thermometer, you can do the experiment.
Let the system sit for a while. Then turn on the faucet and watch
the temperature. You'll see where the pipe is most exposed to the cold
as a function of time.

When I replaced the water service, I discussed the issue with the inspector.
He insists that water meters don't freeze, even tho they're much more
exposed than the rest of the buried pipe. When I started talking
thermodynamics, his eyes glazed over.
;-)

That
still leaves the question of what the OP means by "dripping". I could take
a faucet apart, deform the washer or nick the seat and cause the faucet to
drip even when fully turned off. However, will that be enough to prevent
freezing? I don't know, because I don't know how much the OP wants the
faucet to drip.

As I said earlier, there are lots of details the OP should be sharing if
(s)he wants a definitive solution to the problem.