radiant heatgreenspun.com : LUSENET : Countryside : One Thread
Has anyone used there woodburner or insert to heat water for a radiant floor haeting system?
-- Howard Meyer (BINKI@IX.NETCOM.COM), January 10, 2002
I'm no expert here. We do have radiant heat, powered by an electric heater with geothermal ground source water. Seems to me that a wood burner would be hard to regulate. Our water, during the winter, is about 90 degrees. When its really going to be cold, we push that thermostat up a bit. We have a 3500 sq ft inground home, with 90 % ceramic tile floors. If there's a way to regulate the heat exchange, I guess hot water is hot water.
-- Rickstir (firstname.lastname@example.org), January 10, 2002.
I'm using (or will be using shortly) an outdoor woodburning furnace to run a few heat exchangers and an in-slab radiant floor system in the basement. You have to regulate the water temp going into the slab (<140 degrees F) with a device called a mixing valve. A mixing valve can be set to a specific temp and it will mix the cooler return water with the hotter supply water to achieve the set temperature.
-- Steve in So. WI (Alpine1@prodigy.net), January 10, 2002.
There is a company in north central Wis that specializes in radiant heat and alternative energy, Next Step Energy energy Systems http://www.nextstepenergy.com/html/default.htm
I bought my tubing for my garage and greenhouse floors from him, but don't have them in use yet. He has experience with all kinds of heat sources, and heats his own pace with wood and solar radiant floors.
-- Jim (email@example.com), January 11, 2002.
I have a concrete slab with hot water through standard PVC (yes not CPVC) piping that heats a greenhouse and an ajoining 1400 sq ft office building. I have free wood from my farm. I did not use foam board insulation under the slab but would have if not for the free wood. I used 3/4 inch PVC spaced 12 inches on center. I have several zones, the largest covers 240 sq ft of floor - don't go any bigger otherwise you need a higher powered pump that takes more power i.e. more running cost. In the bathroom I spaced the piping 6 inch on center to have a nice warm floor for the shower. Because I used PVC I have a vented (no pressure) hot water heater and I limit the water temperature to 140 deg F maximum. In practice the water never gets above 120 deg F which is good as the PVC gets a little soft and I feel it may slowly deform at the higher temperatures. The system has an LP gas boiler as backup but I haven't used it for 3 years since I got the Hardy wood burning heater going. The Hardy wood heater has a water temperature thermostat where the hot water is controlled by limiting combustion air. The house wall thermostat turns on/off the Hardy stove transfer pump as needed.
I have 2 pumps, one on the Hardy to transfer hot water to the suction manifold and one circulating pump to distribute water through the gas backup heater and on to the supply manifold. The manifolds are 1-1/4 inch PVC and the weakest piping in the system. The pumps are Grundfos type UPS15-42F and draw 45 Watts each on low speed. Therefore the system requires 90 Watts total and costs $6.48 to run for 30 days at $0.10 per KWHr. I plan to add a PIC micro- controller to the system and believe with that I can optimize my fuel and reduce the running cost by at least half. If I can get the heating cost under $4.00 per month i.e. $1.00 per week, I will feel good about my investment. Also I use rain water to prevent scale in the boilers. It is 10 degrees F outside right now and I am nice and warm. The hot water is running at 108 degrees F and my feet feel great. When I build my house I will use CPVC and put 2 inches of foam under the slab. Need to use high density foam of sufficient compressive strength for the load. I have the design information but I am growing tired of typing and my wife wants me to come eat - hope this helps someone...
-- John Hayes (firstname.lastname@example.org), January 12, 2002.