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Thaw out 350 foot plastic water pipe.

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tcmtech

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Well since someone was saying there are very few challenging threads on the site these days here's a bit of a head scratcher.

I have hot water heat between my boiler system in my shop and the old house. Everything except about 50' out of the ~350' run is buried underground in a 4" corrugated drain tile with a triple layer of reflectix insulation (High R value double foil backed bubble wrap stuff) .
The one part still exposed is where it passes through the edge of the hole for the basement for the new house. I was gone for a few days over the weekend and the boiler was shut down figuring the forecast was saying nothing would be much below freezing at night while I was gone but it froze the pipes just the same.

So given that any theories on how to thaw out a well insulated all plastic pipe inside another plastic pipe other than just wait until the weekend and we get back up into the 50's for a day or two while staying over freezing temps at night and nature does it for me?
 
You're right. That's a poser.

Can you get to the exposed pipe? If so, can you get a MH 200W (or so) lamp close to it? Is there still pressure in the pipe?

All you have to do is get even a little flow going and it will thaw.

<EDIT>On reflection, probably won't work. I didn't read your post closely enough.
 
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Too bad it is not copper pipe. Back in the day they would phone the local welder with his truck. He would hook up to the pipe and run current through it for a hour or so. Worked like a charm.
 
Yea if was obvious and easy I would have already done it. :p

I have a 9 conductor 20 ga control cable that runs the whole length that would make a perfect resistance heating tape given it has a ~ 7.5 ohm resistance for one loop of two leads out and back but being it's on the outside of the insulation and not on the pipe side it doesn't do me a bit of good.

Back when I put it in three years ago I had figured that the basement would have been done and backfilled by now but the wife thought that I should get a job rather than be self employed and work on the new house project so the whole thing stopped dead at that point and the basement never did get worked on. Well she's gone now so hopefully by next fall the basement will be in and this will never be a concern again. ;)

Thus that's how the new house project of three years ago never moved for the last two. I had to get a real job so could afford to pay someone to work on my house for me to make my wife happy. :rolleyes:
 
Too bad it is not copper pipe. Back in the day they would phone the local welder with his truck. He would hook up to the pipe and run current through it for a hour or so. Worked like a charm.
Why not try passing a current through the water/ice in the pipe?
I guess that you would need to disconnect the pipe at each end from whatever it is connected to now. then you could insert some kind of electrode into the ends of the pipe.

JimB
 
Now your talking.;)

The house end of the lines is solidly grounded at the heat exchangers and return pump plus the supply end at the boiler goes through about 6 feet of 1 1/4" steel pipe which is easily isolated from the boiler.

No idea what the actual water resistance is though for a single line that long. I haven't pulled the boiler end off yet and did a megger test. Buest guess is it will be in the upper 100's of K to multi mega ohms range.
 
Or, if you have a small diameter flexible pipe, which can be inserted into the blocked pipe, all the way up to the blockage.
Then inject hot water along the small diameter pipe so that it is carried to the ice blockage.
You may need to feed in more small pipe as the ice melts so that the hot water is acting directly on the ice.

JimB
 
1/4" flex hose with hot brine water? You did not mention the pipe diameter.
 
Sorry I figured that the 350 foot each way to heat a house sort of implied that it was larger diameter Pex line. :sorry:

1" pex and yes I have the boiler end set up where a Tee could be added and a smaller diameter 1/4" Pex line can be feed into the others . Where's the fun in that? :p

But yea if it doesn't thaw out on it's own over the weekend that's the plan. ;)
 
well I went and tied the corrugated tube up along the top of the basement hole so it is in direct sunlight for tomorrow so I will see what happens.

I also wired up two lines of the control cable to make it work as a heat tape of sorts as well. Best guess is it's putting out about 8 - 10 watts per foot so if nothing else it's at least adding heat energy inside the main tube.
 
Thawed out today. Life is good! :cool:
 
Thawed by your method or natural thaw?
 
Fish a smaller pipe/hose inside the frozen pipe. Circulate water IN let it run out the same way it went in. Warmer water will melt the ice. Keep pushing the smaller pipe in deeper.
 
Glad you got it thawed. Hopefully there was not enough freezing to cause a pipe fracture. Maybe come spring thaw get the pipe below the frost line or whatever you planned to do.
 
Natural thaw although I did find that I had water in my outer tubing where it comes into the basement hole so I tracked that back to a loose fitting at the boiler room and gave it a good flush with hot water to make sure I didn't have a ice plug along the way. ;)

Glad you got it thawed. Hopefully there was not enough freezing to cause a pipe fracture. Maybe come spring thaw get the pipe below the frost line or whatever you planned to do.

Yea everything but the open section where basement hole is is below the frost line.

Pex pipe is pretty forgiving to freezing and there are no metal fittings or joints underground along the way that could split if it did freeze solid.
 
tcm, you could always move to SC :woot:!

Only thing that freezes here has a door with a big GE on it... ;).
 
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