Frozen drain pipe dilemma

[idreos]

Last year I had the kitchen and utility room sink supply lines freeze up on me

These sink drains are connected to the same hidden horizontal PVC waste line which parallels an exterior wall.
To prevent that freezing problem from re occurring this week in the current freezing weather, I let the utility faucet drip slightly. I outsmarted myself as the small drip caused my drain line to freeze!

I have put a space heater in the kitchen cabinets facing the outside wall hoping to thaw out the frozen plug, but that has not helped.
I have poured boiling water with salt down the kitchen sink but it only goes through the horizontal pvc drain line and ends up filling the utility sink which is 10' away

I realize the kitchen cabinets have a back wall and a plasterboard wall behind that. The outside wall has aluminum siding and and plywood beneath it.
Any suggestions on how to thaw the ice plug out???

 

[Reach4]

Ouch.

Long term, consider having closed cell foam insulation board added under your siding. That should prevent freezing next year, and help heating bills considerably.

I am not a plumber. I am thinking about taking a gutter heater cable, doubling it over in the middle, wrapping with electrical tape, and shoving the end (was the middle) into the drain line (not through the trap) like a snake. Power it via a GFCI outlet. This may not be a good idea.

 

[Sponsor]

 

[WorthFlorida]

Two problems, 1) thaw out the line and 2) prevent further freezing. But you said supply lines, then waste lines. Are both freezing?

Do you know where the ice plug maybe located? It reads that the ice is past the utility sink assuming the kitchen sink is at the end of the run, then the utility sink before connecting to the main waste line or is it the other way?

Without pictures to make an educated guess, this hidden pipe is behind a finished wall lined with cabinets. Is it possible to place registers along the run to allow warm air to enter this space? This would require cutting a 3x1o" hole through the cabinets and wall but this may give you very cold cabinets that may be like a refrigerator. Do you think are there any traps behind this wall? I ask this for the waste line should be dry most of the way. Is the pitch 1/4" per foot? That trickle of water drained too slow and it froze.

Is there a basement or craw space below? Would it be possible to cut into this cavity to allow warm air to enter? The real fix would be to remove the cabinets, open the wall, properly insulate and then reinstall everything. I wouldn't be a bad project if there is a wife that may want a new kitchen.

 

[Themp]

And you will need to plug the kitchen sink side, so that the hot water does not move in that direction. Also, a comment in the video states that they just used a hose connected to the hot side of the water heater.

 

[Jadnashua]

Opening the cabinet doors may provide enough heated air to help defrost the drain pipe and prevent the supply lines from freezing. With the doors closed, the inside of the cabinet can get colder. It may not be enough to overcome a severe freeze, but it doesn't cost anything and can't hurt unless you've got little ones or animals that might like to explore those open cabinets!

A space heater blowing into the cabinet might help.