This project goes over the installation of a homemade radiant floor hydronic heating system for the garage. The radiant floor heating uses a pex tubing that is installed along the floor of your garage or room . Hot water is passed through the tubing which radiates the heat out into the room or space.
The first step is to figure out what size pex coil tubing and how big of a water heater you would need . Also how many feet of tubing would allow enough heat to exchange into the concrete floor to sufficiently warm up the entire space. The total BTU/hour or heat required will be based on the square footage of your garage or room .
We begin by levelling the ground and start laying down a vapor barrier .The vapor barrier is made out of 6 Mil Visqueen plastic PE film .The barrier keeps the moisture from under the ground to rise up to the surface of the floor. We then lay a mixture of sand and packing gravel before installing the two inch extruded insulating polystyrene foam on the floor and the perimeter.
Four circuits of 800 ft half inch Pex tubing is stapled down on two inches of polystyrene insulating foam using a pex stapler. The eight tube ends are routed upto to a box from where it is connected to a manifold which is mounted on to the wall. The pex tubing with the supply and return tube is connected to the manifold with the help of a compression fitting .
To check if all the connections are OK or if there is any hole or leak in the tubing, connect the manifold to a 100 PSOI air pressure gauge to do a pressure test. Five inches of concrete is then poured over the pex tubing circuits. Saw cuts of less than an inch are made into the concrete to allow for the shrinkage during the curing process.
To insulate the pex tubing and to prevent water from entering into the floor, an expanding foam sealant is filled near the junction where the concrete meets the supply and return tubing near the manifold.
The heating components of this system are mounted on a 4 X 4 square sheet of plywood. The heater has a rating of 7.2kW . The heater is flow activated which requires a circulating pump to pump water through it which then activates the heater based on the temperature setting.
Two 120V fractional horsepower circulating pumps are used , one for running the water through the heater and the other circulates out through the pex loops. The pump has an inbuilt garden hose connector system used for draining.
The hot water coming out of the output end of the heater passes through a pressure tank which removes the air bubble with an air release valve and prevents any water hammer to the system.
This is further connected to the flow activated circulating pump for the heater with connections for filing and draining the system with the help of shut off valves. The water then comes down to a stainless steel manifold and then flows through the supply end of the pex tubing . The heated water splits into four supply loops at the manifold into the concrete floor.
The water then returns back to the return end of the manifold through the other four loops of pex tubing and goes straight through another circulating pump and a Y strainer filter before circulating back to the heater.
Two thermometers are connected at the supply and return end of the pipe to know the temperature difference of the outdoing water and the returning water. The flow is controlled by a thermostat and a switching relay that turns on the circulating pump .