Hey guys I'm installing boiler lines from my shop to the house and will be using the foam in trench method. I'm adding a water supply and extra conduits for low voltage communications.
My question is if anyone ever used PVC conduit chases inside the foam so pex lines can be changed if needed. Long term plans include concreting over the area I'm installing in lines and I'd rather not have to rip up the concrete down the road if I have to service.
The run is a straight shot except for a 4' elevation change so l don't believe it would be difficult to pull the lines through the 100' shot.
Thoughts? If I'm over planning please tell me.
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I will tell you that you are overthinking this:
ideally you want to bed the entire trench in mason sand for one thing; and with a pipe warning tape one foot +- above the conduit.
NOW you can use heavy white schedule 80 PVC pipe to run the pipe-BUT IF IT WERE ME-
1. Dig and level trench below frost line
a. pound wooden survey stakes in the trench right next to the trench wall leaving 6 inches of the stake exposed.
b. bed the trench with at least 6 inches of mason sand and tamp it with a pad tamper before you do anything.
The problem is water
the problem is water
the problem is water
the problem is water
The other problem is heat in the pex
The other problem is heat in the pex
The other problem is foam expansion
The other problem is foam expansion
The other problem is settling in the trench
The other problem is settling in the trench
the other problem is settling in the trench
It will be simpler if you buy the 15 dollar per foot oxygen barrier pex foamed tubing and slide it in the white PVC MAKING SURE YOU HAVE AN EXIT ANGLE OF 30 degrees to install it and eventually pull it out to replace it if needed.
YOU HAVE TO to place the PVC along one wall of the trench and back fill it with the mason sand and tamp it in several layers to avoid issues with settling that could shift the pipe in the trench.
BE SURE to shovel sand against the trench wall where you place the pipe before you lower the pipe in place.
To make your life easier when working on this:
first rent a wire snake, buy some wire lube, 100 plus feet of new poly rope, rent a pipe vice to clean and glue all the white PVC together, preferably rent two pipe vices to clean and glue the entire pipe section together in one operation You can glue the 100 foot section together with the two pipe vices and lower it in the trench with the 30 degree elbows and short pipe sections that exit and enter the home and shop.
You can bed the smaller PVC pipe along the other wall of the trench.
You say are adding water lines
I would use another run of PVC pipe for the water line using the blue plastic water pipe and push it through
to the house/shop and be sure its below the frost line. You could use a larger black flexible PVC pipe to run the water line and the oxygen barrier pex through to the house/shop etc and use black PVC for the communication line as well JUST BE SURE TO BED the pipe properly and then tamp the sand in the trench in layers all the way to the surface of the trench.
SO you can use conduit or white PVC or the black poly pipe its up to you if you use the black poly it will
not be as strong as the white schedule 80 PVC and less costly than electrical conduit. Using the 15 dollar
insulated PEX in the solid drainage tubing will keep the heat in the pex.
using mason sand will be less costly in general
So if you have a 4 foot by 18 inch by 100 foot trench you need at least 22 yards of sand to a backfill it fully.
