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[powers1976]

I have two runs of  about 200' each , so the pre-made stuff at 10.00 a foot is not an optionany other ideas besides wrapping the pex I'n the 5' insulation from lowes and putting it I'n corrugated pipe?

[yoderheating]

 If you are not going to use good insulation I would at least stop and start the pump if possible and also use pvc conduit instead of corrugated pipe because I would guess it would be a better insulator. 

[BoilerHouse]

Have you checked out insulated Pex on ebay.  They have a range of prices including some available for 4 dollars a foot.  I bought mine from Anderson's (through ebay) and so far I can't complain.

[PhinPhan]

I would just be careful going the homemade route, you don't want to be heating the ground, you will lose a lot of heat that way.

[Ridgekid]

Agreed. One of the biggest mistakes any DIY'er can do is install a poorly designed under ground pex line. My dealer went "cheap" a few years ago on his own install and ended up replacing his lines this summer. Lessons learned.

[Bill G]

     Not an expert by any means, but maybe consider 2 seperate heating units placed much closer to buildings being heated.  Agreed 400 ft of the good stuff would bankrupt most of us for sure!! 

     Best of luck,

Bill

[oldchenowth]

There has been talk on here of spray foam in the trench.  Would that be viable?  Hire an insulation company to lay a bead down put the pex in place and lay another layer on top. Just a thought, I have no idea what $$$ we are talking, just another option to consider.

[jerkash]

Expensive!!

[willieG]

ball park figure here of heat loss of 1 inch uninsulated pex pipe burried inside a hollow air filled pipe..somewhere in the area of (this is a guess and likley a low ball one at that) 40 to 50 btu per foot per hour

for easy figuring lets say 50 btu per foot per hour. you say 400 feet (is that one way?) this could be 800 feet round trip taht gives us 800 x 50 btu that give us 40000 btu of heat loss per hour or  960,000 per day  that in my opinion would be about wasting one years wood supply each year

now i am basing this on only guessing as i have figures for copper pipe that use an hot temp of 140 and the outside temp of 70 (1 inch copper would lose about 30 btu per foot per hour)  i beleive that pex would not lose heat as fast as copper but  in the scenerio we have, we would have a temp spread much larger 180 in the pipe and only about 50 in the air around the pipe and then the dirt around the air would be drawing a little ahrder as well so i say 50 btu per foot of pipe per hour is a fair number to use? (some one maybe able to do better)

these are just guesses but i can tell you this..when you see 400 feet of thawed ground in mid january that is about 2 feet wide you will say...AH HA that is where all my wood is going!

[oldchenowth]

Didn't know the $$. Mike Holmes uses this stuff like it's cheaper than air in his builds.  Guess we don't have his pull or friends, huh?

[oldchenowth]

Just thought of something.  Styrofoam blocks.  Your state transportation testing facility most likely tests huge foam blocks for light weight fill in roadways.  Cut to fit in your trench and surround your pex.  I just picked up about 30 blocks of it to insulate my pole barn walls.  Gave the tested blocks to me so they would not have to dispose of it, filled a 20' enclosed trailer stem to stern and they have more.  Pain the the ***, but might be worth looking into.  Dow or Monsanto or Dart container plant nearby?  Maybe they have tested stock they would shed for free or cheap. Put it in a chipper and pour it in conduit\drain pipe.

Just my $0.01 worth of knowledge

[rhugg]

I used the 10' pcs of black tubular pipe insulation.  It comes in big sizes so you can wrap multiple lines in it and pull it thru.  I duct taped it together in places but it has a glued self seal joint also (along the split).  Get it below frost line and keep the water out of the corrugated.

Is my method better that wrapping it in 1/4" material?  Who knows.  I also had some junk 1" board foam that I laid over the corrugated befor I backfilled. 

By all means insulate it but understand that you get diminishing returns for the added cost.  The question comes down to where it is best to spend the budgeted $ doesn't it?

[Scott7m]

Just order you some good triple wrap, it's not near 10 dollars a foot.  Most of it loses less than 1 degree every 50-75 feet depending on the type.  I personally see little point in some of the 15 buck a foot stuff. 

I wouldn't make my own, you can't even come close to making it as good as the store stuff and most people destroy it pulling it through. 

[mikenc]

I have two runs of  about 200' each , so the pre-made stuff at 10.00 a foot is not an optionany other ideas besides wrapping the pex I'n the 5' insulation from lowes and putting it I'n corrugated pipe?

Any insulation would be better than none. you will pay for good insulated pipe in wood savings alone not to mention your stove have to run doublle the amount to heat your house. Like has already been mentioned I would consider using  eitherpvc  conduit or sch 40 pvc pipe as a outside covering.

[RSI]

You can get insulated pipe for $5-$7 per foot that it going to have very little heat loss.
If you make something equivalent it will cost you close the same or more in time and materials
The corrugated pipe is probably not very strong that Lowes sells either. (None around here but what Menards sells is much weaker than the premade insulated pex comes with)