Tommy Mac Discussions › Forums › Fix-it Forum: Home Improvement & Do It Yourself Repair Forum › In-floor heating/concrete floor › In-floor heating/ concrete floor
You will need approx. 3 loops @ 300 feet max, per loop of 1/2 inch diameter wirsbo-hepex pipe. Or another brand that has an oxygen barrier in it. (Oxygen barrier keeps oxygen out of the hydronic system). You will firstly have to put down insulation on the floor to keep the heat from travelling downwards into the ground. What are you going to use to heat the water??? Electric, gas, or oil? The water tempature cannot exceed 120 degrees F . This temp is to low for most boilers, the return water temp shouldn’t be lower than 160 F on boilers. I don’t know where you live, ( the outside design tempature). How hot do you want the temp inside the garage to be? How good are the doors, do they leak, and are the walls insulated? The walls WILL have to be insulated. You could use a domestic gas water heater to heat the floor in some states, depending on local codes, if this is the case, this would be the cheapest way to go. You would need to elevate the water heater in the garage about 48 inches off the floor, the part that could ignite gasoline vapors. Again depending on local Codes. Or if this garage is attached to the residence the heater could be installed in the basement of your house, or in a ulitilty room. You’ll need to put gycol in the system with a 30% ratio. You will need two header manifolds with 3 outlets. I would install 3 valves on the loops of 1 of the headers to help remove air. You would need a backflow preventer to keep the domestic water seperated from the water in the heating system. After the hot outlet on the water heater you will need a air scoop and a air vent, to remove air. After the air scoop you’ll need a circulator pump. Example a Grundfus 1542F pump. You could wire a 110 volt wall thermostat to run the pump. Tie the pipe using snap ties to the rebar,on 12 inch center spacings. Remember your loops shouldn’t be longer than 300 feet. There is a option of using a LOW TEMP. Boiler, like a Hydrotherm,(Lennox), Viessmann the Viesmann’s are priecy. If the present water heater in your house is large enough you could use a copper plated heat exchanger with a circulation pump, from the water heater through one side of the heat exchanger, and another pump on the other side of the heat exchanger into the in floor heating loops, by doing this you will not need a boiler, or water heater in the garage, etc… You will require to add gycol only for the in floor heating loops. You will need approx 27,000 BTU for heating the water. If you are going to cut the concrete with a saw to avoid cracking you will have to install the piping below the rebar. This can be done by putting down wire mesh or a few rebar rods on the corners diagnally and attaching the piping to it. This will Keep piping out of harms way. Install the first pass of piping nearest to the doors. Tie the piping every 4 feet. If unsure consult a local heating contractor. You can do some of the work but NOT ALL, if gas fitting is involved. Infloor heating is 18-30 % more efficent than forced air.
Good luck on your project.