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  1. #1
    Join Date
    Aug 2011
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    2

    Default Radiant floor canít keep up?

    Had radiant floor in stalled on my first floor about two years ago and what Iím finding is it has a hard time keeping up on the coldest New England days. Current config is 3/8 Onix stapled up. Aprox 2Ē air gap with foil foam and fiberglass bat.
    Tried maxing the mixing valve but still donít get much over 65.

    60ís 1 Ĺ story cape recently renovated, new windows, doors, fully insulated.

    Thanks

  2. #2
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,208

    Default Re: Radiant floor canít keep up?

    Was there a heat-loss done before the system was installed? It sounds like you don't have enough radiation or the water heating source is not keeping up.

    John
    Last edited by johnjh2o; 08-31-2011 at 09:23 AM.

  3. #3
    Join Date
    Aug 2011
    Posts
    2

    Default Re: Radiant floor canít keep up?

    Not sure on the heat-loss, system was installed as part of a full 1st floor renovation.
    Boiler was sizes for an eventual addition and an indirect hot water tank.

  4. #4
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,208

    Default Re: Radiant floor canít keep up?

    Doing a heat loss is the first step in any heating system, with out that it's just a shot in the dark. I would check with the contractor that did the job. Depending on the area of New England your are in the system should be designed to heat your home to 70 when it is 0 outside with a 15 MPH wind.

    John

  5. #5
    Join Date
    Sep 2011
    Posts
    1

    Default R-Value

    A regular heat loss won't help you out. You need to reverse engineer the system and start with a radiant heat loss and design. This will tell you whether you can or cannot heat the space radiantly based on the existing installation method.

    In radiant there is more to the loss. You must use the subfloor and finished floors R-value to calculate the needed water temp to overcome the heat loss. Once this is done you then look at the existing system.

    Is there enough tubing in the floor? How is it zoned? Are there floor sensors? Is solar or some other outside heat gain influencing setpoint? Is the floor off for a long time and we can't catch up due to response time (chasing the night).

    I've fixed hundreds of systems done in the fashion you have and you must start as if the radiant isn't even in the home. Do the math, re-engineer, compare and solve.
    Last edited by ChrisM; 09-05-2011 at 07:19 PM.

  6. #6
    Join Date
    Mar 2008
    Location
    nova scotia, canada
    Posts
    1,522

    Default Re: Radiant floor canít keep up?

    im with chris on the question regarding the zones. did the installer correclty size each zone. if the zones are too large the system will be straining to keep the correct temperature as the water will not return to the boiler quick enough to maintain the correct temp
    fire up the saw and make some dust

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