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General: Under floor heating on top of Limecrete

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  1.  
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      CommentAuthorMichael1
    • CommentTimeNov 1st 2008
     
    Hi all,
    I am going to lay a Limecrete floor and want to use Electric underfloor heating with Oak flooring,I have been told that I need to lay a levelling compound for the cable/heating, I am thinking that this would take away the breathability of the Limecrete. Any solutions to this? I don't want a wet system.
    Thanks
    Michael
    • CommentAuthorCWatters
    • CommentTimeNov 2nd 2008 edited
     
    I have to admit I'm sceptical when it comes to breathable floors. I'm not even sure I've seen a good explanation of what breathable means in the context of a floor. Presumably there is no DPM as that would stop anything getting through (eg stop it being breathable)? Is the idea to allow any moisture that come up through the floor to evaporate away? If so it seems risky putting oak on top as oak is quite susceptable to changes in humidity/damp. In addition I'm not sure I like the idea of electrics in a possibly damp floor?
    • CommentAuthortony
    • CommentTimeNov 2nd 2008
     
    For underfloor heating please install a wet system then you can make it hot with what ever energy you like.

    Direct electric would be the most expensive choice from running cost view point. 1 kW electric = 1 kW of heat

    ASHP for example would give you 3.5 to 4 kW of heat for every 1 kW of paid for electricity. Solar energy comes free
    •  
      CommentAuthorMichael1
    • CommentTimeNov 2nd 2008
     
    I don't want a wet system as I shan't be using the place full time (its in France) and want the efficiency of Electrity without having to rely on Oil deliveries and tanked Gas, also the house is going to be well insulated and airtight so hopefully I won't need to much in the way of heating (thats the plan anyway) Water will be solar panels. The Limecrete floor will be well drained and pumice stone used as the hardcore then Limecrete on top allowing it to breathe? I don't want to put in a regular concrete floor as I believe the damp underneath will migrate towards the stone walls and wick upwards. If I am wrong about this then please feel free to point out any problems I might meet.
    Thanks
    Michael
    • CommentAuthortony
    • CommentTimeNov 2nd 2008
     
    I cant understand why you would rather be 100% efficient than 350% or 400%?

    If its unoccupied then you wont need hot water so you could pump unwanted solar hot water round the ufh rather than wasting it, this would keep the chill off.
  6.  
    Micheal you are right that limecrete on a pumice is a very good breathing floor that doesnt require a DPM, thus allowing the floor to maintain its own humidity levels whilst staying dry (the pumic negates the need for the DPM as it is capillary negative)

    I think that you are also right that there is a risk that any ground moisture will be forced towards the walls with a plastic DPM.

    Have you thought about useing hemp in the lime for the base slab on top of the pumice to give extra insulation?

    oak flooring is v nice but dont you think you are mitigating the advantages of underfloor heating by not using something with more thermal mass?

    Are you also putting in a gravel drain of some form outside the walls?

    Are vent tubes going to be buried in the pumice hardcore leading to the outside air?

    Just out of curiosity I would be interested to know where you are in France to get an idea of the type of ground and weather and also what thickness of pumic and limecrete you are putting down.
  7.  
    I think Tony has a point, especially if you are using wooden flooring which isnt the best surface for underfloor heating. ASHP makes sense if as you say it will be fairly airtight and insulated (multifoil???)
    • CommentAuthortony
    • CommentTimeNov 2nd 2008
     
    I was thinking of ASHP to make warm water for the ufh but yes it could be used direct and then for air cooling too if you needed that.
    •  
      CommentAuthorMichael1
    • CommentTimeNov 2nd 2008
     
    Excuse my ignorance but what is ASHP. I am hoping to seal it up as tight as a drum.
    Bot de paille my Barn is near Barenton, Lower Normandy.I will put Hemp in the Lime, Pumice 200 mm and I think 100 mm for the Limecrete more if its needed, I am going to put vent tubes in the floors as they are 11metres x 7metres. The walls are going to be Hemcrete 300 mm thick from floor to ceiling, a French drain around the outside. I am going to strip the roof off and redo it with thick insulation (haven't chosen this one yet so open to ideas). Triple glazed windows and doors.
    Tony, how does this work? do I have to have a back up to go with the solar water heating and If so am I into Gas and Oil?

    <blockquote><cite>Posted By: tony</cite>I was thinking of ASHP to make warm water for the ufh but yes it could be used direct and then for air cooling too if you needed that.</blockquote>
    Thanks
    Michael
    • CommentAuthortony
    • CommentTimeNov 2nd 2008
     
    ASHP = air source heat pump
  11.  
    ASHP Air source heat pump
    do a search on this site for it
    some info here
    http://www.earth.org.uk/air-source-heat-pump.html

    here one of many manifactures
    http://www.calorex.com/Product_range/Domestic_ground_source_heat_pumps/introductionASHP2.htm

    cheers Jim

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