Antifreeze - not just for cars

I don't understand. How can freezing of water in a p-trap present a significant problem?

Water will still be in the supply lines, probably even if it is drained, and can freeze. If the water was not shut off the house could be flooded when the supply pipe splits.

During the phase change from liquid water to solid ice, the water (ice) expands. It can easily crack the pipe. So that when the weather warms up, the drain trap leaks.

Unless the drains were clogged, why would there be any water in them? And what little is left in the traps would have plenty of room for expansion. What you need to do is shut off the main water supply valve, and then drain as much water as you can from the supply pipes by turning on ALL the taps, especially the one in the laundry sink (in the basement), if there is a tap down there.

Why is the power off? Reasons beyond the owner's control, or what?

This seems unwise, viz. denies power to lamps and burglar/ fire alarms. Many insurance carriers deny coverage when electricity is shut off. Canadian houses empty for a week to several months in winter usually maintain elec. connections and set furnace heat at 45 to 50 deg. Fahr., with an alarm to report if the electricity should fail.

I'm hoping you bought RV type antifreeze and not automobile type. You don't want to flush auto stuff down the drains to contaminate the water supply.

The function of water in a P-trap is to prevent sewer gases rising into the house. It is cheaper to refill the traps with non-freezing liquid than to chance months' exposure of soft furnishings to sewer gases, which is likely to be incurable.

That's true, but not relevant to this situation. Think about it a moment, then forget about it. It's the least of your problems. The supply pipes are the main issue.

He specifically said it was RV antifreeze.

And you drained the pipes, if heat stays off and it gets zero or below for awile even the HW tank can be at risk, but you have Ng so a gen can run the heating system

They can freeze and crack, here it get to -20f, eventualy the roaches and termites die without heat but the rodents live.

Tony wrote in news:7o9qloF3ou993U1 @mid.individual.net:

........

why not just turn the heat on?

Rodents can die also. I saw an electric box full of straw and dead mice after a mobile home was shutdown for a couple winters.

the traps WILL break duh.

the drains don't go to the water supply. duh.

If I put liquid in a glass jar, but leave enough headroom and don't tighten the lid, I can put that jar in the freezer and the jar won't break because there's room for expansion. With me so far?

After I run water in my sink or tub, the pipes end up empty except for a very small amount in the U-shaped trap. Since there's plenty of room for expansion (above and below), why should there be a problem? It certainly couldn't HURT to use the anti-freeze, but the OP didn't mention shutting off the water and draining the pipes. Seems to me that's where the real problems will occur, since those pipes are under pressure and sealed (until they break).

Because he said the power got shut off. He didn't say why, but based on the information we have (as opposed to "what if...?"), there is no heat available.

Unless the drains were clogged, why would there be any water in them?

CY: The drains would only have waer, if they were horizontal runs.

And what little is left in the traps would have plenty of room for expansion.

CY: I think I remember hearing of traps cracking. The ice expands sideways.

What you need to do is shut off the main water supply valve, and then drain as much water as you can from the supply pipes by turning on ALL the taps, especially the one in the laundry sink (in the basement), if there is a tap down there.

CY: Yes, there is a laundry sink. I'm also concerned the water pipes may have low spots or horizontal runs. Might not be able to get there with my generator and compressor.

Why is the power off? Reasons beyond the owner's control, or what?

CY: I'm not totally sure. the house is unoccupied, and beyond that I'm not sure.