I moved into a new house and noticed it got very cold the other night. The thermostat had no power. I went to inspect the furnace, which is in the basement, and found the condensate pump had filled up with water and shut power to the thermostat (and furnace?). Most of the water likely came from the humidifier that dumps into the condensate line. Further troubleshooting revealed the condensate pump's drain line (copper), which runs outside through my basement wall, was frozen in the 10°F weather. As a quick fix, I diverted the pump's drain line directly to the utility sink in the basement. Then, I insulated the outside copper line with a length of "pool noodle" insulation and duck tape. Now, I'm not confident this will keep the line thawed when it gets really cold, so I was thinking of tapping into the copper line inside the house and installing a secondary, overflow line that could divert water to my utility sink. So, if the main copper line freezes outside again, physics will handle the rest, and divert the water to my utility sink.

I'm hoping someone may have some advice on best practices for installing something like this, as I'm sure the location, orientation, water pressure and drain line gauge must all be taken into account. I understand plumbing is quite a delicate science, so I prefer to avoid the ol' "trial and error" approach.

I'm open to ideas, too, if anyone has been through this before. For example, I read a post where someone recommended removing the pump's check valve so any residual water left in the drain line would flow back into the pump reservoir after the float valve dropped and shut off the pump. Then, no water would be left in the copper drain line to freeze.

Thanks for any help you can provide. I'm willing to barter some computer and network communications know-how for any help you may be able to provide.

if you have a sink available, why not install a branch tailpiece betwee the bottom of the sink and the trap. then let the condensate drain into it?
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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Would a branch tailpiece (I'll have to google that) be easy to remove? I understand it's against code here to dump "created" water down a drain (water that didn't come from the town water system). I'd want to be able to undo this quickly, if need be. I like this idea, although, this creates a vent from the sewer into my basement. The overflow line would keep any sewer gas inside the condensate pump's drain line.



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The branch tailpiece goes between the sink trap and the sink's drain assembly. There's no route for odor to escape.

Thank you, that makes sense. Might it be a fact that I'm technically not supposed to run condensate drains to the sewer due to laws that only permit me to dump water that I paid for (from the town water supply)?

you pay a sewage fee for every gallon of water that comes thru your meter. unless you have a seperate meter for outside watering, you are paying a sewer charge for the water you wash your car with or water your lawn with. i wouldn't worry about a gallon a day of 'created water'...

"I read a post where someone recommended removing the pump's check valve so any residual water left in the drain line would flow back into the pump reservoir after the float valve dropped and shut off the pump. Then, no water would be left in the copper drain line to freeze. "

Not a good idea, because when the pump shuts off, the water in the line will drain back into the reservoir, raising the float valve and causing the pump to come back on. So the pump will be stuck in an endless on/off cycle as it the reservoir refills every time it shuts off.

Here is what I did, I added a standpipe to the existing kitchen drain line. The trap keeps sewer gasses out of the house, and that black section is a check valve. Since this is in the basement and below the flood rim of upstairs fixtures, I thought that a check valve would offer some protection in case of a back up in the main line.



I took this pic in the summer with the condensate pump line from the dehumidifier, we have since upgraded to a condensing boiler, so the line from the boiler's condensate pump goes into this standpipe too. This has been operational since last July, so far no issues.