My wife and I are buying a 1500SqFt (Log) house with a 5400SqFt warehouse. We're planning to heat the warehouse with a Waste Oil Boiler, as it's zoned commercial, and I will be doing Fleet repairs to my cars and lite trucks, and rustproofing vehicles with grease. Anyways, the house is about 125 feet away, separated by the driveway, soooooooo.....
I priced the blue 4" corr plastic with two 1 1/4 pipes, and locally it's $15 -$18 a foot, which IMO, is NUTS!!! A freind found various other similar UP (underground piping) for alot less, but I was concerned about the heat loss with only about 1" of insulation.
Soooooo..... without having read this post, I thought to buy 8 or 10" corrugated ridgid sewer pipe, barrier PEX suitable for the heat of the boiler, which can exit as high as 240f, but I'll run it much less if neccesary, and have a foam truck on the site to fill the sewer pipe as I lowered it into place, using some kind of brace to center the piping. Possibly 1" wood with two 1 1/2" holes inserted every few feet as we went along.
One of the things the Clean Burn Boiler (waste oil) tech told me was return temp must be above 140f, and below that, ash will condense on the boiler tubes, causing corrosion. To avoid this, I'd go with the extra closed cell foam in the trench, and they have a tempering valve to add outlet hot water to the return to maintain adequate temp
I'd have to use the corr sewer pipe as opposed to just foam in a trench with poly, as the whse is separated by the driveway.
Here's the prices I got...
Heat Barrier PEX 1 1/4" 20' @ $56
Heat Barrier PEX 2" @ $115
Corrugated roll 6" 100' @$140
Corrugated Ridgid 8" 1 foot @$6.50
Corrugated Ridgid 10" 1 foot@$10.50
Spray foam truck? No Clue, but I'd budget $1000