PEX tubing, How deep?

[S.Crum]

This summer I'm building a big outdoor boiler to heat the house and main shop. The boiler will be sited about 1/2 way in between. I'm plumbing this with the PEX triple wrapped 1" tube in the plastic sewer pipe type outer shell. I'm told this stuff can be run right on top of the grass (but would be hard to mow around). Ideally in our area pipes like to be buried at 4' to 5' depth. This is ok but I already have most of the area between the house. main shop and plasma building criss crossed with conduits and water lines. can this PEX be buried at 18" to 20" without issues? 1 driveway has to be crossed and I have a 20' piece of 6" steel pipe I would run the PEX thru under the drive. I'm in northern central Pennsylvania.

 

[paridgerunner]

I would think at 2' you'd be alright, but would run the risk if your pump failed i suppose. A friend of mine outside of Mansfield, Tioga County put one in the beginning of winter, didn't bury the line until the next spring, just let it across his yard to get him going for the winter, he told me he never had a problem, didn't freeze, of course if your pump goes down and your not around, could freeze, but I think you'd be alright.

 

[Iowa Ron]

How expensive is this tubeing?? i have been thinking about a out side wood burner [boiler] figure it will cost 6- 8 k would buy a lot of l.p

 

[mickey350]

I did my whole house using PEX - it's less than copper, and less labor. If you are using for a boiler, you need the PEX than can handle higher temps - Oxygen barrier or something like that. Look online for Radiant Heat Supplies - try www.radiantec.com to get an idea. try ebay too - you can get a 300' roll for cheap. When you are working with it, build yourself a spool with a couple of saw horses and a pipe, otherwide you will get tangled up in blues. Also, be careful not to kink it.

 

[city farmer]

IF YOU NEED INFO ON PEX CONTACT A LOCAL PLUMBING SUPPLY HOUSE AND ASK THEM FOR THE REP FOR YOUR AREA WE USE A LOT OF THIS IN FLORIDA FOR WATER LINES INSIDE OF BUILDINGS THERE ARE A LOT OF PEOPLE THAT MAKE THIS KIND OF PIPE UNDER DIFFRENT NAMES WE HAVE USED IT ON A FEW PLACES WHERE IT WAS USED FOR UNDER SLAB HEATING YOU SHOULD HAVE NO PROBLEM WITH IT AS LONG AS YOUR PUMP DOES NOT QUIT ARE YOU PLANNING ON INSULATING THE PIPE IN THE GROUND WILL BE SOME HEAT LOSE IF NOT

 

[mickey350]

They use PEX for driveway melting systems, so you should be fine. Just keep the pump circulating the water when it's below 40 degrees. Circulating water will not freeze. You'll also need a mixing valve so you don't pump 180 degree water.

 

[Anonymous-0]

does it get there in winter? might be worthwhile to get it deeper where the ground temp is more constant so you lose less heat in the line from the boiler. im no expert at this, but just something you think of when you live in Canada lol.

 

[dlplost]

you use a antifreze mix from the boiler to the building and a heat exchanger in the building, so it can be as deep as you want it, or need it, it dosn't matter.

 

[T_Bone]

Hi s.crum,

What you might consider doing is running the supply and return line as a larger single pipe to a point inside the dwelling where it goes into a header manifold then distributes/returns to each zone.

This way you only have one supply and one return pipe to deal with undergound and/if they ever froze or leaked, then it would be a simple repair than dealing with several pipes.

Another item would be a single wire on the outside out the plastic pipe. This could be used to thaw out a frozen line. I sure would go atleast the depth of my frost line for your area.

I would also look at putting closed cell pipe insulation around the underground pipe then slip another protective pipe over that. This would keep the "underground critters" from tearing up the insulation over time.

When you double the pipe size, it will carry four times the volume. So a 1-1/2" pipe will carry the volume of four 3/4" pipes.

As the water temperature rises the water will expand by approx 20%, so be sure to include a expansion tank in your plans at the high point of the system with a automatic air bleeder.

T_Bone

 

[bradk]

18" will be fine.Places where you drive over should be covered with galvanized pipe(won't corrode) or such to prevent crush.

Definitely use antifreeze glycol mix.

 

[bc]

Pex is good stuff. It will not burst when the water freezes. Once it does freeze, getting it thawed is another matter.

 

[John in MD]

They recomend 18" down here for that triple wrap in 4" corrugated drain pipe.