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  1. #1
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    Default Hydronic Under Floor Heating

    We are in the process of building our home. We are at drawings stage and looking at the best of options for heating our new home. Natural Gas is not piped to our street so we have been advised that hydronic underfloor heating (water pipes in the concrete slab floor heated by an external heat pump) is the next best way to go. We are wondering if anyone in this forum has had this installed and looking for their thoughts on the system in terms of practicality, efficiency and cost. We understand that the set up cost is far greater than any other heating system and that the key to the project is the size and efficiency of the heat pump itself which is $10k alone.

  2. #2
    Awaiting Enlightenment R2x1's Avatar
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    Default Re: Hydronic Under Floor Heating

    Shutting off the heat during hot spells (or turning the wick up in a cold snap) is just not an option.
    Entropy is not what
    it used to be.



  3. #3
    In a 1920s time warp Terry Porritt's Avatar
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    Default Re: Hydronic Under Floor Heating

    Wikipedia has an interesting article on underfloor heating:
    http://en.wikipedia.org/wiki/Underfloor_heating

    I thought the final paragraph was important:

    "Although underfloor heating is generally less expensive to run than radiator heating and more comfortable, the floor covering needs to be compatible: a highly insulating floor covering (such as thick carpets or cork) can reduce the efficiency of underfloor heating to the point where a conversion to underfloor heating may not be practical."

    So if you want thick pile carpet, then underfloor heating would not be a good idea, on the other hand if you like hard floors, with no coverings, like the Romans with their mosaic tile floors, then it would be ok

    Googling other sites also suggest that electrically heating a floor is a cheaper installation.

  4. #4
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    Default Re: Hydronic Under Floor Heating

    This gets discussed on www.ecobob.co.nz

  5. #5
    tweakedgeek tweak'e's Avatar
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    Default Re: Hydronic Under Floor Heating

    i've worked on a few places that have under floor heating.

    electical (ie element under carpet or in concrete) i wouldn't recommend. they LOVE to attract lightning or power spikes. last time i looked at them they didn't warranty them unless they had adequate lightning protection.

    heat tubes, seen one with cooper heat tubes. basically a heat pipe from the fireplace. solid tube no water etc to leak or ever need fixing.

    solar. i'm told the problem is where do you put the excess heat during summer. you can't shut the system off. some use a swimming pool as a heat dump for all the excess heat.

    water pipes. the ones i've seen have run off boilers tho a wetback is another way. one in particular had a big house with tile floors. the nice thing was the house and floor didn't feel hot, it was just comfortable. you didn't notice the heated floor (or even that the heat was on) until you walked onto an unheated section.
    the floors warmed up quickly but that would vary depending on what heat source you use.
    using heatpump to heat the water i haven't seen but one thing you may want to consider is using a ground system. instead of pulling heat from the air (with noisy fans) they pull it from the ground (drill a big hole or trench and lay the pipes in that). big bonus is its quiet and ground temp doesn't change a lot so it can work well even in very cold climates.

    important thing tho is loosing heat from floor into ground. i've heard of polystyrene inbetween ground and concrete but its not very good. the main thing is actually keeping the ground DRY. good drainage is required, it must stay dry even in winter.
    Tweak it till it breaks

  6. #6
    Senior Member pctek's Avatar
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    Default Re: Hydronic Under Floor Heating

    Quote Originally Posted by tweak'e View Post

    important thing tho is loosing heat from floor into ground.
    Hmm.
    I'm not a fan of it. Hot air rises for one thing.
    For another, I live in a cold area, I have wooden floors. There are a lot of gaps and so on in some outer bits as well.

    The only heating I have is the woodburner in the lounge and I have never had cold feet anywhere except out in my laundry - which is semi outside of the house and has the gaps in it.
    wipe your paws.

  7. #7
    mikebartnz
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    Default Re: Hydronic Under Floor Heating

    Quote Originally Posted by McChief View Post
    so we have been advised that hydronic underfloor heating (water pipes in the concrete slab floor heated by an external heat pump) is the next best way to go.
    Seems like a waste use a heat pump to heat the water which is then piped. It would be more logical to just use a straight heat pump air conditioner.

  8. #8
    Noobish Pirate hueybot3000's Avatar
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    Default Re: Hydronic Under Floor Heating

    Not sure if it was this certain crowd that I saw but at a job I was on the floor was cracked throughout because the piping weakened the structure of the cement on the floor. This building was maybe 4 years old but you could feel the roughness under the carpet in places.

    Heatpump is the way to go, maybe even two depending on the size of the house. And duct the air between rooms and from the ceilin space

  9. #9
    Golden Oldie
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    Default Re: Hydronic Under Floor Heating

    Copper Pipes buried in concrete - need to be well lagged to ensure the lime in the concrete does not corrode them and cause leaks -expensive to put right.
    Problems with plastic pipes - high coeff of expansion of plastic. ( Ok for cold water - problems with hot.)

  10. #10
    Awaiting Enlightenment R2x1's Avatar
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    Default Re: Hydronic Under Floor Heating

    Copper has a fair amount of expansion too, as does stainless (the proper plumbing material)
    Entropy is not what
    it used to be.



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