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[pennyrilehunter]

Hello all.  First post but have been reading for about a month.  I’m contemplating purchasing and installing an OWB and looking for some advice on insulating the underground lines.   I will have @100 ft from furnace to crawlspace and then @ 75 ft to heat exchanger.  I live in Western KY and high groundwater is not a problem.  I was thinking about installing  2 1” Pex lines in 6” cellcore DWV schedule 40 and insulating each line with ¾ wall semi slit Polyethylene foam (advertised R 4.7).  Cost would be @ 7.40/ft. Could save @ 1.15/ft. if I used two 3”PVC instead of the single 6”.  Would ½” wall insulation be sufficient or go with the ¾”?  I know water inside pipe = trouble but would think properly glued PVC should be as water tight as anything and definitely tougher than the corregated tile. I thought about putting a Y where the line comes up to the furnace and basically making a riser that you could cap off and use to pump water out of the line if it was ever a problem.  Do you ever have problems with a pex line going bad and leaking?  If so I would think it would be possible (not easy though) to pull and replace a line if done this way.  I know the premade stuff is really god but if I can save $500 to $700 and have something as good I’ll definitely put in a little labor.  Many thanks for your thoughts or suggestions.

[RSI]

I would just go with 5 wrap. It will most likely have less heat loss and will save a lot of time. Also might even be cheaper.

The drain tile that they use isn't the same as what you find at most building centers. It is much heavier.

[6pacmac]

I would just go with 5 wrap. It will most likely have less heat loss and will save a lot of time. Also might even be cheaper.

The drain tile that they use isn't the same as what you find at most building centers. It is much heavier.

  I like the 5 wrap also.   Alot of bang for the buck imo.   I bought mine off Ebay for under $6.00 a foot.  My buddie made his own lines with pex,  split foam insulation and pvc drain pipe.    He now wishes that he had bought  insulated line because of the heat loss,  melting snow that he has now.   Good luck!

[Scott7m]

Don't skimp on the line, I've never seen homemade line be worth a hoot.  If you want some good line for around the same cost go with 5 wrap, great stuff

Even basic 3 wrap would be far superior to what your talking about making...   

So really I don't think your going to save any money up front, and def not in the long run.

[pennyrilehunter]

Thanks for the advice.  I thought of a few other questions.

1.  I assume that there are several companies making the 5 wrap, are any significantly better/worse than others?  If so which ones should be avoided?

2.  How is the wrap sectioned together and sealed?  Is it overlaped and taped, butted together and taped, other?

3.  What are your thoughts on using aluminum vs standard pex?  I understand fittings may be harder to find but would it help in long runs (175 ft) for expansion issues?

[RSI]

As far as I know only one company makes 5 wrap. It is a single piece of insulation for the first 3 layers. I don't remember off hand if one or two pieces are used for the last two layers. It is taped all the way down the seam at the 3rd layer and at the 5th layer.

1" (it is actually 26mm ID but sold as 1") Pex-al-pex is a larger diameter than regular pex so will give you better water flow. It is almost as big as 1-1/4" pex.
It also has pretty much no expansion compared to pex. It is harder to work with but not terrible. The fittings should be no problem if you order them when ordering the pipe.
I would switch over to regular pex inside the house though. Makes the install much easier.

[Bull]

Welcome to the site pennyrilehunter