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Radiant Floor/ Geo-thermal

Has anyone ran a floor heating system with Geothermal as the heat source. I have a customer that is wanting to do this and I have heard differnt out comes. Any feed back would be good.

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  • GMcD
    GMcD Member Posts: 477
    Radiant heating and cooling

    Yes, there is no problem as long as the usual design issues are addressed. The first one being to minimize the heating and cooling loads, then, second, minimize the heating and cooling loads, then third, minimize the heating and cooling loads. The key with economical geo heat pump and hydronic systems is to minimize the system temperature requirements by designing the house to have minimal heat losses and heat gains, thus reducing the size of the geo-exchnage system and mechanical plant. Ideally a radiant heating system that requires no more than 85F and a radiant cooling system that requires no lower than 64F water and you're in business. Also don't forget the energy balance on the system. There are some good guidebooks out there for geo systems and doing them right rather than designing by rule of thumb.
  • Karl_5
    Karl_5 Member Posts: 6
    Geo-Thermal

    Using geo for your heat source is no problem. I install Econar's geo system's for radiant and forced air, no problems. The kicker is I live in northern Minnesota. The max water temp out of a heat pump is around 118 degrees. Staple up can be an issue, depending on floor coverings. This temp also works for forced air. Heat pump water coils are usually more dense so you can get more output with lower water temps. Cooling is awesome, up here we set our tekmars for 44 degrees. For new construction geo is the only way to go these days.........of course this is my opinion. I also do reto-fits, the biggest problem there is the duct work is always to small. Good luck
  • Ken Caverly
    Ken Caverly Member Posts: 12
    85 degree design temp??

    How can you design a system only requiring 85 degree water and still provide enough heat for comfort.Is it correct to assume for this low temp you are not providing for carpet?. This means a hard surface floor like tile, laminate or concrete. With even a 10 degree temp drop your average water temps will be 80 degrees. the floors won't be as warm as the water so I am guessing the floors will be around 70 degrees. These floors aren't warm enough to provide that radiant warmth effect and it will result in a "cold 70 " house.

    On days that don't reach design day won't the floors even be cooler and even make them feel less comfortable.
  • Nron_13
    Nron_13 Member Posts: 164


    maybe 85 degree max floor temp Hey Jeoff ?
  • John Koll_3
    John Koll_3 Member Posts: 9
    Geo air handler

    Karl, do you know of a ducted air handler with both a chilled/heated water coil and a variable speed blower motor?
  • John Koll_3
    John Koll_3 Member Posts: 9
    Geo air handler

    Karl, do you know of a ducted air handler with both a chilled/heated water coil and a variable speed blower motor?
  • GMcD
    GMcD Member Posts: 477
    Yes, 85F heating temp, and lower

    Yes, it's all about minimizing the heat losses in the first place. There are a number of radiant slab systems running right now where I am with a surface temperture of between 72F and 75F and it is perfectly comfortable, with an ambient air temperature of between 67-70F. This is documented, and I just toured some folks through these buildings last week and they couldn't believe it either. Granted these are projects with radiant slab ceilings, not floors. If you want floors, then I have a high rise concrete dorm cluster (three at 8 stories each) up at the local University where the slab floors and ceilings have tubing, and the heating water temperature is running at 74.5F to maintain a 72F slab surface temperature, and it's perfectly comfortable.

    And you're right, you are "just guessing" if you don't pay attention to the math and the proper design. Your "beliefs" are coming from a history of trying to use radiant floor heating to make up for too much heat losses.
  • GMcD
    GMcD Member Posts: 477
    Sort of

    The problem we have in North America is that we continue to use very inefficient radiant systems like staple-ups, and joist bay systems where the fluid temperature has to be so high in order to penetrate the insulating layers between it and the floor surface. Conduction is King with radiant tubing, and tubing in a concrete topping or warmboard type system on top of the floor enables low fluid temperatures to be used, due to the more efficient conduction and heat transfer from the tubing to the floor.

    Of course the first key is to minimize the heat losses of the building so you don't need high heating fluid temperatures in the first place.
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