Thornhill Snow Melt - Phase 1

Project Overview

Excavations underway - 850 sq. ft snow melt in Thornhill

Tearing up this almost new driveway to install a snow melt heated driveway for this Royal Stone customer.  60 PSI commercial grade R10 Styrofoam with Uponor Wirsbo 3/4″ PEX tubing. We will be running a polyethylene 1-1/4″ underground gas supply line to an NTI 175 TFT boiler.  We have oversized this boiler to allow for future expandability of in floor heating and possibly a 50K BTU air handler for the garage. This home owner regrets not having installed a snow melt 5 years ago when they originally installed the interlock.  Better late than never.

poly gas line
gas supply trench

Notice that the gas supply line is taken directly off of the gas meter and not shared from the basement furnace.  Typically for larger appliances, dedicated gas lines must be installed to ensure proper combustion. Later on we will add the risers to this line and tie it into the gas meter with shut off valves.  Notice the tracer wire.  The underground gas line is a polyethylene supply.  Once a copper tracer wire is wrapped around it, it can be toned out for future locates.

When passing through a garden, grass or any other part of the property, the gas line has to be at least 15″ below final grade.  When going under the driveway, it has to be a minimum of 24″ below final grade, hence the dip in the trench.  Code above all.

Rough gravel is laid as a base for our Styrofoam insulation. As this customer may park a heavy vehicle in their driveway, they opted for the 60 PSI commercial grade insulation to provide a little bit more strength under the pad. The insulation had a built in vapor barrier as well as ‘pucks’ to hold the tubing in place. this particular insulator has 8″ centers as opposed to the industry standard 9″.

snow melt
heated drivewqy
heated steps

Above you will see Tes mounting the tubing onto the uncoiler.  Without this contraption, laying PEX would be extremely messy and difficult to control.

The lines are all installed and secured into the Styrofoam pucks. Notice how the supply and returns all come in on one side of the slab and then branch out to the individual loops. We have a 5 loop driveway which keeps our loop length at about 235 ft each loop

The steps are framed and secured. We zip-tie our PEX onto the re-bar to ensure it does not shift while the concrete is being poured as we want an even melt on the steps as well.

Pressure test for concrete pour

Pressurizing the pex lines for leaks is a critical step of the process. We leave them under pressure until the concrete has been poured and cured. The pressure in the PEX provides resistance to the weight of the poured concrete and prevents the tubing from contracting. The last purpose it serves is to make sure the tubing is not punctured during the pour.  Subsequently if damages occur, air escapes in a very violent manner, making everyone around well aware of the puncture.

Concrete has been poured and the pressure gauge is still holding.  You can see the snorkel tube left in the middle of the slab.  This is a conduit for us to run the wire for the snow melt sensor.  

The PEX lines all comes together beside the garage in a methodical supply and return way.  These will tie into a manifold on the inside garage wall.