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[coolidge]

If you could, would you use sprayfoam and make your own lines instead of using Thermopex or Logstor. I figure I could save roughly 2500 bucks and have a much higher r value

[juddspaintballs]

I'm obviously in the minority on this subject, but I spray foamed in place with no ill results and 0* heat loss between boiler and house.  I dug the trench, lined it with plastic sheeting, laid my lines, and spray foamed lifting the lines a couple inches as I went for full surround on the pipes.  I wrapped the extra plastic over the top of the foam and left it.  When I buried the foamed pipe, I had about a 1' diameter glob of foam around two 1-1/4" pipes for a super insulated package. 

[Sloppy_Snood]

No I would not.

[mlappin]

Whats going to protect your foam from heaving or tree roots?

[Sprinter]

Tree roots follow water, if no water no roots, many have used this method with very well documented results. Spray foam isn't just water resistant but water proof.

[crankshaftdan II]

If you could, would you use sprayfoam and make your own lines instead of using Thermopex or Logstor. I figure I could save roughly 2500 bucks and have a much higher r value

I too, am looking into the spray foamed method of lineset encapulation as I do NOT have any trees growing in the general area where my runs will be located!  I might be concerned if I had any Willow trees close by-they will find a way to break into black cast-iron sewer pipes to find moisture!  From what I have gathered from reading on this and other forums-Frost and heavy equipment/Truck traffic might be a problem??  The H.D. version of the closed cell foam to use has a 26 PSI rating and is completely waterproof as previously stated.  I plan on putting mine down below the 4' mark due to high frost concerns in a very cold area.  The less amount of heat loss the better and $$$ savings can be used in the rest of the Install.  Cranky

[coolidge]

I am thinking I am going to go this root ( not tree root) if I move my boiler. I am going to try and center the lines in sch 40  pipe and fill it with closed cell. I have a silicone coating I could run through my airless sprayer to seal any and all joints. Still in the planning process, will lost picks if this happens.

[willieG]

found on the net....true or not, it is worth asking around more before you do this


Polyurethane foams can be made ‘open cell’ or ‘closed cell’ Open cells foams are not water proof and allow water to permeate via the open cells. Twin component foam is designed to be closed cell. However, scientifically, no polyurethane foam is ever 100% closed cell as the cells sacs making up the foam can and do rupture and this will leaves a percentage of open cells. The percentage of open cells is, however, quite low. A ‘closed cell’ foam is best described as water resistant rather than water proof in much the same way as timber is water resistant but not technically water proof. In practice, closed cell foams afford excellent water resistance and can be applied under roof slates and tiles to prevent the ingress of rain and snow. A depth of foam of 90 mm will give a vapour permeability of less than 1 perm (55ng/m2.s.Pa) which affords vapour barrier protection.

[jerkash]

I don't think it is worth the gamble of doing your own.  Sure some have done it with no problems and saved ton's of money.  Others have done it, found out it didn't work and then bought the good stuff.
It's your money so I would suggest you do with it whatever you would like and keep us posted!

[mlappin]

They swear by the foam in trench method at Hearth.com. 

I'm however going a different route. I already have 6 inch PVC buried to the house. I'm going to dig the two corners up, pull the line out I have then most likely go with the 3 wrap from Zsupply. From the boiler to the shop we still have to dig that trench. I'm again, most likely using zsupply again but a 5 wrap as its a longer run. A piece of 6" PVC will just slide over a 5" tile from experimenting. I also have to cross the driveway twice. Semi's and tandem grain trucks dive over both places it has to cross. I'll most likely get a piece of 8" culvert to run the PVC thru at each drive crossing.

[LittleJohn]

The MOST important thing to remember when burying lines for energy transfer, is to get a good seal all the way around.  Because water infiltration KILL efficiency and steals BTUs. 

I personnally would not build my own, but hey what do I know.    Its nice to know that in most cases if I install a premade product from a supplier I have some sort of warrenty/guarentee for a period of time.  Plus how much is spray foam going to cost vs. Thermopex, Logstor or other under ground pipe manufacturer??

[Sprinter]

It all depends on your local spray foam contractors cost, it's the long runs and or using larger than 1" pipe when the foam in trench is much cheaper. You would literally have to submerge the line set and expose it to enough ground movement to crack the foam for it to fail. And I don't think the soil will be bending line sets past 30 degrees in a short length to crack. With the foam there are no air spaces for water to fill.

[coolidge]

Here is a test they did in Canada, it is not the SAME but it is still buried foam, I do agree you need to get a good seal.

[Sprinter]

Very good results for direct burial, a lot better way than how we were using the 2" foam board on all the houses. Nailed up and seams untreated.
That's pretty cool how the r value went up on the second year. 
I've seen the purple treated spray foam used a few times where direct weather exposure or fire exposure was.

[Sloppy_Snood]

The "problem" with spray polurethane and foam board exposed directly to soil is...........

BUGS.

Citronella ants, carpenter ants, and,,,, termites can all live in this foam. 

I would be hesitant to use "foam in the ditch" method or foam board without treating the dirt/foam interface with termite pesticide (in particular, fipronil aka Termidor;  simply put, nothing works much better on termites and ants than fipronil at this point in time).