Homeowner Installed Radiant Floor Heating System

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The following article and photos were written and photographed by, and are the courtesy of Bob D.

After watching many "home improvement shows" we decided to try our hand at installing a radiant heat system in our log cabin.

	We originally cleared the land and erected the log cabin back in 1973. This was a family project and one that has given us great joy over the years. We have continually worked on this project as money was available all the while raising our family of three, getting them through college and on their own. Time marches on and although we have always enjoyed our wood burning furnace it was evident that if we ever wanted to sell the property we would have to put in a heating system. After watching many DIY shows the decision was made to go with radiant heat. A system that would supplement our wood burning furnace, but could also kick in as the full heating system if necessary. First, we contacted a radiant heating specialist and gave him the square footage, number of rooms, windows, doors and type of building material including the insulation values in the home. He then calculated the heating needs and using the design rule that no loop should be greater than 300 feet,he divided living areas into groups of equal size loops and determined the number of manifolds that would be needed. He, also gave us the confidence that we could accomplish this and would be there to help if needed. Having this "can do" attitude really buoyed our spirit and we were ready to go. This information was put into a detailed list of the materials needed to complete the project. Then, we started planning.
	By laying out the entire area on scaled grid paper i.e.: 0.1 to 1" scale we were able to plot the spiral layout to exact dimensions. This was invaluable to us, as more time spent on the planning saved us time and energy on the laying of pipe.
	4"x 8' OSB boards (less expensive than plywood) were cut into strips. Starting on the outer wall, planks of OSB boards were screwed down, working around the perimeter spiraling inward to center of the area. Allowing for the diameter of tubing gives you the first row around the room, the "warm" (or supply side from the water heater and the second the return "cool" or return to the water heater to be re heated). We made a template that rounded off corners and then used the cut off piece to make the corner. This was a time saver as you just put the template on the end of the board, jig saw, push the corner up into angle and your'e good to go.
	We used a combination of 7", 8" and 12" planks which controlled the spacing of the spiral. Once the OSB planks were down the tubing is fitted in between.
	Aluminum plates, were fabricated (which I had also made a setup for to bend to shape), this also saved time and money. The plates are laid down under the tubing at intervals. More plates around outside walls and less in center depending on where you want heat concentrated. You wouldn't need too many under a bed or furniture for example. NOTE: FROM MY HVAC PARTS - a word of caution here about not putting too many under a bed or furniture. Furniture usage could change in the future, or a buyer of the home may not even have the room as a bedroom as a couple of examples.
	Here is a shot with the new flooring installed.

	All zones are piped to a central station where each has it's own controller and circulatory pump.

A high efficiency propane gas water heater supplies the heated water to a heat exchanger which keeps the heated water separate from the potable water (drinking water). We, have fired the system up and found it to be very comfortable. Since this is a second home that we leave during the winter, the "Winter closing down" was quite simply blowing the pipes out. You could use anti-freeze. The bottom line as "old-time DIYer's" is, we found this project to be do-able. We used fifty-five psi of air pressure to test the system for leaks between weekends -- fortunately, we were able to go forward every week as we came back to find no leaks. This also fit very well into the scheme of things as by the end of each weekend we were dragging and happy to have to put the system to the test. Would recommend you have a floor plan so that you know how many loops you'll need. It took us approximately twelve weekends to remove the existing floor, replace with OSB, tubing and aluminum plates, tie all zones (three in all which included two bedrooms, living room, dining room, kitchen, bath and hall) into a central station and laid the wood planked finished floors. There is a fourth zone that will be expanded in the future.

It ended up costing more than we had originally thought but we saved on manifold connections to the central panel using pex brand tubing rather than copper. Still think we will recoup expenditure when, and if, we sell.