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Discussion Starter · #1 ·
I have a 1930's house with a 6' high crawl space under my front porch. There is an opening that connects this space to my full basement, but the crawlspace is fully outside the termal envelope. My water meter and about 20' of 3/4" copper are located in this crawlspace. Thankfully, it has never froze due to the small amount of heat transferred from the opening leading to the basement and some foam insulation.

I am tearing down the porch to rebuild this summer and would like to address the vulnerable pipe/meter and close the doorway off during winter months.

I was thinking about burying the line and relocating the meter to the basement, but I don't think I could easily get down below the frostline (42") and it would also require me to undermine the stacked stone foundation wall which has no footing. I could add fill over the line, but that doesn't really appeal to me, if I can avoid it.

Is leaving the pipe as is and using a heat tape product a viable option? I never really considered that as an option, but was the recommendation from a tech at the water company.
 

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if you have a 6' crawl space you could just bury 4' of it

you could run a small heat run there and heat it too...just keep the damper almost all the way shut so it keeps the room at 50 degrees or so
 

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Capra Aegagrus
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Is leaving the pipe as is and using a heat tape product a viable option?
Perfectly viable, until you have a power outage or the heat tape fails. People all over the country use that solution. Use of that solution has caused some of them to become my customers.

Seriously, you could get by that way for many years--but burying below the frostline is completely passive and about as bulletproof as you can get.

If you really don't want to do the digging, just insulate the daylights out of it and keep a faucet dripping during bitter cold spells.

Don't forget.
 

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I would think that if you put some xps over the line extending out 4' in each direction, that would heat up the area underneath. I know you can do this with a foundation wall, so it should protect a water line as well.

Maybe you can find some studies which have been done on this.

You could put the xps down, then put enough dirt on top to keep it in place.
 

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Discussion Starter · #7 ·
House is heated with steam. There is no radiators in the basement, just the pipes and boilers. Also, moisture is a concern. House is built in 1931 on stone foundation... No vapor barriers or drain tile. The porch is 28x8 and will be covered with hardwood decking. ventilation under the decking would negate any efforts to heat the space.

I wouldn't think Insulation alone won't do anything as it's essentially outside. Eventually the temp would equalize as there is no heat source, regardless how much insulation is used.

I guess burying it and running the pipe under the existing doorway is the best solution. That way I won't disturb the existing foundation. I couldn't imagine the tape being reliable and have never used it before. I don't put much faith in $79 electrical products from china when it's failure can result in damage to my home.
 

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The heat source is coming from the center of the earth. The cold is coming from above the earth.

At a certain depth, the temperature remains steady at the mean annual temperature.

Above that depth, the temperature fluctuates.

The dirt above that depth insulates the stuff below from the temperature extremes below. For example, when it is cold above, it remains warm below. When it is warm above, it remains cool below.

You can trade insulation for dirt.

So if your frost line is at 4', and you have 2' of dirt on the line, then you need to figure out how much insulation you need to replace 2' of dirt, then your line will be protected as if it is 4' deep.

Can you dig it?
 

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Discussion Starter · #9 · (Edited)
I understand the concept of frost lines and the higher temperature of the soil. I was referring to insulating the pipe.

Interesting concept on the R value of the soil, in regards to replacing it with insulation. I will have to look into that. Going down 2-3 feet is easy (relative) if I can make up for it with XPS. May work, but I will need to be certain...I would rather freeze an exposed pipe than one that's buried.



Edit: just did some reading. There is no solid R value of solid due to variance in moisture content and composition, but engineering principals give a range of 0.25 - 0.8 per inch of soil at 20% moisture.

Comparing 0.25 to the typical R5 of xps makes me think it's doable.
 

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my gut was telling me to just put it under 2" xps and as much dirt as possible. It seems the 2" will be the same (r-10) as 40" of dirt.

I think your research will tell you that wet soil insulates better than dry, which I think is counter-intuitive.
 
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