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Thread: Radiant Heat

  1. #1
    Join Date
    Dec 2010

    Default Radiant Heat

    I have a small house that we added a second floor to. The gas hot
    air heat is in the attic now and feeds the whole house through ceiling registers. Two zones, one for each floor. The first floor always seems cold in the winter, with the second floor nice and cozy, even though thermometers read the same on both floors. Naturally the firt floor hardwood floor is like ice with a unheated crawl space under it. We've tried adding humidifiers on the first floor but that doesn't help. As a solution I was thinking of putting in a radiant heat system under the first floor and feed it from my water heater. This system hopefully would warm the floor a little downstairs and make it more bearable in the winter. Naturally is nice and cool on the first floor in the Summer! Has anyone done any radiant floors?

  2. #2
    Join Date
    Feb 2008

    Default Re: Radiant Heat


    There are probably 4 or 5 ways to solve this problem---in ways probably you and I can't even imagine at this point----but they would all involve having a number of heating techs over to the house to offer their individual solution and cost estimates.

    It's against local codes in most places to use the hot water heater (which involves potable water) for heating lines.

    But other possible solutions may involve radiant & non-radiant approaches.

    One would be to modify the forced hot air system to include ducting in the crawl space.

    Another would be to add a HEAT EXCHANGER into the plenum of the furnace ducting to create a hot water circuit that could be used for radiant sub-floor heating on the 1st floor.

    A separate HWH could be used to create a radiant sub-floor circuit, assuming there is enough access in the crawl space to install the radiant tubing.

    The initial stragegy should be to try to work with the heating system you have now (forced hot air) to modify it & get some heat to the hardwoods on the 1st floor---this would be your best chance for the least costly solution.

    Radiant may be the solution, but it will be more costly due to labor installation costs and a number of complicated components that don't come cheap: mixing valves, heat exchangers, zone valves, circulator pumps, etc., etc.

    Consult the Yellow Pages under "Heating Contractors" & get several techs in there to see what they offer for a solution, along with their cost estimates.
    Last edited by NashuaTech; 12-30-2010 at 11:35 AM.

  3. #3
    Join Date
    Dec 2010

    Default Re: Radiant Heat

    It may be possible, depending on the size of the floor and water heater usage.

  4. #4
    Join Date
    Jun 2010

    Default Re: Radiant Heat

    I wouldn't recommend an open system. It is also illegal in some states so please check with your local building dept. You could add a heat exchanger off the water heater to close the heating system from the domestic but again you would need to check with your local building dept to make sure it is legal.

    You should also have a heat loss of the room done in order to calculate what water temps you would need to overcome the heat loss of the room. I would recommend the use of a floor/air sensor for the radiant due to there being another heat source for the room. You want to maintain a floor temp and don't want the hot air system to keep the radiant off for long periods of time. You could program in a set floor temp that you want to maintain. You need the heat loss to accomplish this.

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