Vacant winter house: drain traps

[Snowman9000]

I read the FAQ on winterizing, but this topic didn't get much coverage.

In a 5 month absence, I'm pretty sure the sinks, baths, and toilet traps will end up uncovered as the water evaporates. I know some people say to pour vegetable or mineral oil in, or RV antifreeze.

What do you do? (Other than have someone stop by to keep them full).

[joebedford]

RV antifreeze in all the traps but I leave the heat on a bit. My alarm system monitors the temperature and calls in if the temperature goes below 4C.

[rhagfo]

I worked with a traveling construction superintendent that had a house in Minnesota. He and his wife traveled together he did two things to protect his house. They had a house cleaner come in once a week to clean and check on the house, she gathered the mail and sent to ther current location. He also had a large red light in the front window that would come on if the temperature in the house dropped below a certain temp, the his neighbor would call and let him know.

[John_Joey]

Snowman9000 wrote:
Interesting tidbit about evaporation of RV antifreeze. This matches my experience, that RV antifreeze evaporates almost as soon as water.

The evaporation rate of a liquid is directly proportional to its vapor pressure. At 25 °C the vapor pressures for water, pure propylene glycol and pure mineral oil are, consecutively, 24 torr,[2] 0.1 torr[3] and <0.01 torr.[4] Be aware though that the properties of "RV antifreeze" which has propylene glycol in it will be different than pure propylene glycol because alcohol, water and other ingredients are in it. One manufacturer of RV Antifreeze gives the vapor pressure of their product as 17 torr at 20 °C.[5] This material, if placed in a drain, will evaporate almost as fast as water. Some makers of RV Antifreeze will list the vapor pressure of their product as 0.1 or <0.1 torr. This however is only for the propylene glycol component, not the mixture that comprises their product which can be mostly water.

https://en.wikipedia.org/wiki/Trap_primer

:h

For over 20 years I used RV antifreeze in my cabin with never an issue of evaporation in the traps. I would let the cabin go cold though.

Currently I have a bucket mouse trap in the garage I leave all winter. It has RV antifreeze in it, with no evaporation issues to speak of. My 2c is I would not be so concern with evaporation as much as I would be with freezing temps. Not all traps are easy to get too to repair. RV antifreeze is less then $3 a gallon. Cheap insurance in my books in case of a long power outage.

[almcc]

Snowman9000 wrote:
You can buy pure propylene glycol at a farm store, about $20/gallon.

I'm about at the point where I'm just going to forget about the whole thing. I wouldn't be surprised if that's what most people do.

Probably the best bet. We don't worry about it, only problem that I've had was with a toilet trap that was drained caused by the pump in the basement (that pumps up the wastes to the main drain then into the septic system) running continuously because the float valve failed. I have to let this pump run because of the condensate draining from the high efficiency furnace (I leave the furnace on at 50F).

[Snowman9000]

You can buy pure propylene glycol at a farm store, about $20/gallon.

I'm about at the point where I'm just going to forget about the whole thing. I wouldn't be surprised if that's what most people do.

[Snowman9000]

Interesting tidbit about evaporation of RV antifreeze. This matches my experience, that RV antifreeze evaporates almost as soon as water.

The evaporation rate of a liquid is directly proportional to its vapor pressure. At 25 °C the vapor pressures for water, pure propylene glycol and pure mineral oil are, consecutively, 24 torr,[2] 0.1 torr[3] and <0.01 torr.[4] Be aware though that the properties of "RV antifreeze" which has propylene glycol in it will be different than pure propylene glycol because alcohol, water and other ingredients are in it. One manufacturer of RV Antifreeze gives the vapor pressure of their product as 17 torr at 20 °C.[5] This material, if placed in a drain, will evaporate almost as fast as water. Some makers of RV Antifreeze will list the vapor pressure of their product as 0.1 or <0.1 torr. This however is only for the propylene glycol component, not the mixture that comprises their product which can be mostly water.

https://en.wikipedia.org/wiki/Trap_primer

[NanciL]

pawatt wrote:

NanciL wrote:
We live at elevation 3200 feet in the NC mountains where many nights and days it is well below freezing and belowzero.
I shut the breaker to the water heater off and drain it.
I drain all the water pipes( I have low pint drains) and then I put regular auto antifreeze in the traps. It won't evaporate like Rv antifreeze.

Jack L

Don't use regular antifreeze, it can poison your water supply.

It can't get into my water supply.- Please tell this old plumber how ????
I started using it about 15 Years ago when I came home to find that the regular RV antifreeze had evaporated.
And yes, I have a thirty year old septic tank and the small amount that goes into it has never hurt the bugs yet

Jack L
I'll continue to use it since it works so well

[owenssailor]

pawatt wrote:

NanciL wrote:
We live at elevation 3200 feet in the NC mountains where many nights and days it is well below freezing and belowzero.
I shut the breaker to the water heater off and drain it.
I drain all the water pipes( I have low pint drains) and then I put regular auto antifreeze in the traps. It won't evaporate like Rv antifreeze.

Jack L

Don't use regular antifreeze, it can poison your water supply.

Yes - regular auto antifreeze is toxic. It should not go into systems that go to either septic or municipal sewage systems. A good amount of RV antifreeze in the drains and toilets works well.

[pawatt]

NanciL wrote:
We live at elevation 3200 feet in the NC mountains where many nights and days it is well below freezing and belowzero.
I shut the breaker to the water heater off and drain it.
I drain all the water pipes( I have low pint drains) and then I put regular auto antifreeze in the traps. It won't evaporate like Rv antifreeze.

Jack L

Don't use regular antifreeze, it can poison your water supply.

[John_Joey]

FWIW, I used V-oil once in a rig that I leave south. When I came back it was a goo that was a mess to clean (this was in the RV toilet.) I ONLY use RV antifreeze now. YMMV

[NMDriver]

RV antifreeze is cheap and you want to put some in the toilets and toilet tank also.

If you may loose your heat source then you should drain the hotwater tank, and any appliance that may have water accumulated in the piping like a washer, dishwasher, etc.

[1995brave]

Here is a link on how to winterize a house or building. Antifreeze maybe all you need since it does not evaporate.

[Snowman9000]

Dutch_12078 wrote:

Snowman9000 wrote:

1995brave wrote:
Are you leaving the heat on?
If not then pink stuff.
If on vege oil.

The house will be heated. Why veg. oil then?
Thanks.

The veg oil will lay on top of the water and help keep it from evaporating.

I don't think it will. It will cut the evaporation in half, but the water on the back side of the trap is open to evaporation. Unless we fill the trap with oil. Right?

[Snowman9000]

jplante4 wrote:

Snowman9000 wrote:
The house will be heated.

What kind of heat? The reason I ask is because I had a problem with low pressure in a forced hot water system over the winter we were gone because I shut the water off and there was no way for the boiler to make up for normal pressure loss. There were no leaks in the system, but the pressure went low enough to burn up a circ pump.

Since then I've learned that you should pipe in a makeup water supply before the main water cutoff. However if you do this, be sure to run the P/T valve overflow to a sump. I had an expansion tank go when I was home and in 20 minutes the P/T valve put an inch of water in the basement.

I hope to keep this thread on the question of drain traps.
🙂