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Housing - New Build: MVHR for small Passive bungalow/1.5 house

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  1.  
    • CommentAuthorHOWARDJ
    • CommentTimeAug 28th 2012
     
    Having decided to (probably) build a 1.5 house but omit the stairs and only live in the ground floor (see General--Small Passive Bungalow thread), what impact would this have on the MVHR system?

    I presume it would be sensible to size the system for the whole house.The upstairs would effectively be an insulated loft. Can /could the MVHR be zoned to minimise the heat to the loft by perhaps having a much lower air exchange rate to the loft, or would the fact that the loft is effectively sealed be an advantage, in that if south facing roof windows were installed,would it get additional heat into the building?
    Presumably 1 extract and 1 inlet would all that would be needed initially?

    We are hoping that MVHR with an in -line small electric heater will be sufficient. We intend to install solar thermal and PV.( With large s-facing 3G windows.)

    Not sure what to do about a back-up system as all electric and no mains gas.Would rather avoid oil and LPG and associated tanks etc. Small wood stove would be ideal but reading various threads that has its own problems!

    Howard
    • CommentAuthorRobinB
    • CommentTimeAug 28th 2012
     
    Posted By: HOWARDJThe upstairs would effectively be an insulated loft.

    Just to be clear are you planning to go for insulation in the floor or ceiling of the loft space? If the former then I'd build in the ducting and blank off the vents in the unused part of the building - or leave open just a crack to keep it fresh.

    For back-up simple panel heaters for quiet or fan heater for a quick warm up. If designed right you'll never or hardly ever use them. Also if your MVHR is using a simple in-line heater (i.e. no heat pump) then it will be no more or less efficient than any other form of electric heating. Great to hear you're planning PV and ST

    RobinB
    • CommentAuthorEd Davies
    • CommentTimeAug 28th 2012
     
    Posted By: HOWARDJPresumably 1 extract and 1 inlet would all that would be needed initially?

    Consider, though, that retrofitting ducting is likely to be awkward so it might be worth fitting now in at least some places.
    • CommentAuthorHOWARDJ
    • CommentTimeAug 28th 2012
     
    RobinB

    We would insulate the roof so that the WHOLE of the habitable space would be inside the thermal envelope.

    <blockquote><cite>Posted By: RobinB</cite>Also if your MVHR is using a simple in-line heater (i.e. no heat pump) then it will be no more or less efficient than any other form of electric heating</blockquote>.

    From what I've read the jury seems out on whether a heat pump has any real benefit,or have I got it wrong?

    Ed Davies.

    Not sure that we will even fit out the loft initially just board it out. Praps. even leave it to future owners.

    Howard
    • CommentAuthordjh
    • CommentTimeAug 30th 2012
     
    Posted By: HOWARDJWe are hoping that MVHR with an in -line small electric heater will be sufficient.

    Hoping isn't a very good plan. If your house isn't quite to PH standard for some reason, the MVHR won't be able to provide enough heat and you will have to use your backup in normal use. If you want to use MVHR heating, you need to use PHPP for the design, and then make sure you build to the design.
    • CommentAuthortony
    • CommentTimeAug 30th 2012
     
    The greater your heat losses are the more heat you will need to add and the larger the volume of that you will need to transport this heat

    They said that in my case my MHRV would not be capable of it but my whole house heat loss in October is only 100W so the air system is easily capable, only struggles when temp gets down well below -3C

    If yours is going to work you will need large or very large ducts 200mm diameter I would say or larger to all rooms
    • CommentAuthorHOWARDJ
    • CommentTimeAug 30th 2012
     
    djh,

    Point taken. We were intending to use a PH designer anyway.Just trying to get a better understanding of the system in a part used house.

    The back-up I was referring to was what to use in the event of an electric outage, for what ever reason. We will be at the end of the power line.

    tony

    Thanks for the advise re ducts.

    Howard
    • CommentAuthorHOWARDJ
    • CommentTimeAug 30th 2012 edited
     
    edited
  9.  
    MVHR - Where is Viking House?
    • CommentAuthorRobinB
    • CommentTimeAug 30th 2012
     
    You can't add an inline heater to Viking House's FiWi AFAIK.
    • CommentAuthorHOWARDJ
    • CommentTimeAug 30th 2012
     
    RobinB

    My thoughts also.

    Howard
  12.  
    We are looking at an add-on heater for the Breathing Window having both water and electricity as options but it would probably cost £500. A bigger 6kW imersion in the cylinder costs £50 and a 5kW electrical resistant heating cable that we sometimes build in between 2 plasterboards in a wall in the TV room costs £100. With this option you choose a wall where no paintings will be hung and it directs radiant heat exactly where its needed.
    • CommentAuthordjh
    • CommentTimeAug 30th 2012
     
    Posted By: Viking Housea 5kW electrical resistant heating cable that we sometimes build in between 2 plasterboards in a wall in the TV room costs £100. With this option you choose a wall where no paintings will be hung and it directs radiant heat exactly where its needed.

    Traditionally, that's why heaters are built into the ceiling instead of the wall - no pictures hung on the ceiling, though I don't know what they do about mirrors on the ceiling!
    • CommentAuthorsnyggapa
    • CommentTimeAug 31st 2012 edited
     
    Posted By: djhI don't know what they do about mirrors on the ceiling!


    they would remain mist-free is my guess :shocked:

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