Round 2, Insulated Underground Pipe

[MyOutdoors]

Well, since I made the fatal mistake of rushing into my OWB install last season, I put in 1" pex which was undersized for my application, I also went with a BHS pipe which I found to lose quite a bit of BTU's. So I'm chaulking this up as a costly lesson that hopefully people in my situation can learn from.

My thought now is that I will install 1-1/4" pex in a a 3-4' trench. I believe I'm going to go with the DYI Tiger foam kits. I'm going to separate the pex 2" with a rigid foam block. What type/brand of pex should I use for the best actual ID". How much foam should I put down below/side/above pex. Any and all suggestions would be much appreciated since this is the last time I want to do this!

 

[stee6043]

From the reading I've done on this site on this topic it sounds like most people will run (2) 1" lines instead of (1) 1-1/4" line. 1-1/4" pex can be very expensive. I'm sure others will chime in as well.

Good luck with your retrofit!

 

[heppm01]

I'm interested in this as well.

Tip: you might want to change the thread heading to something more descriptive. "Round 2" might not catch the eyes of the right people...

 

[coolidge]

I,m no expert on the pipe size but i have sprayfoamed quite a few of these setups. You will save some money by finding a contractor to do the spraying. Those kits are quite expensive. I usually put 6" closed cell foam all the way around the pipes.

 

[MyOutdoors]

I called a local contractor and they quoted me 2k for 165' of 3" foam on all sides. That's way to steep to do it that way. Tiger foam goes for $610 for 600 bdft. for there DIY kit. Add that to the cost of 2 1 1/4" pex and they DIY option looks to be alot better and less expensive. I'm going to try and call a different contracor as well. the one I spoke with didn't have much experience with spraying pipe in trenches.

I've also run into this product which is local and I can pick up for $1250. This would be for 112 cu ft.

http://www.dritherm.com/index.html

 

[harttj]

I know most people like to calculate based on 20°F delta T, but it looks like if you based your calcs on 40°F delta T you may be alright. This essentially doubles the BTU's you can carry. I know nothing about BHP pipe quality.

Since this is a OWB and not a gasser your not worried about getting the BTU's away from the boiler to storage, but simply to the end user.

Tim