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Heating and cooling: MVHR with internal air source heatpump?

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  1.  
    • CommentAuthorDarylP
    • CommentTimeJun 29th 2010
     
    Hello all,

    I am looking for a whole house MVHR system that has an inbuilt air source heat pump.... this is to help with the DHW demand at times when the internal air temp of the dwelling is high.
    In effect it will be acting as 'air-con', but instead of wasting the heat into the outside air, using it to (pre-)heat DHW.

    Paul do hint at this on their website but I cannot find it explicitly mentioned... :confused:
    Does anyone know of such a system, or how to incorporate an internal air-water heat pump into a MVHR system?

    Thanks in advance :smile:
  2.  
    I've been looking at the Paul Compakt 360dc, see attached. Green Building Store are willing to import it, but I wouldn't mind betting it's more expensive than separate MVHR & ASHP.

    David
    • CommentAuthorRobinB
    • CommentTimeJun 29th 2010
     
    I talked to Regavent about a similar system, though I wasn't absolutley sure I understood what they were doing. It was linked to the Ecocent heat pump in some way.
    • CommentAuthorevan
    • CommentTimeJun 29th 2010 edited
     
    Nibe make a exhaust air heat pump which sort of does the same thing but I don't know if it returns the cooled air to the house.

    Sounds like quite a good idea when you've got an overheating problem but not so sure about the rest of the year.

    Hockerton housing project used something like that (took warm air from the conservatory area), maybe they could give you details of the equipment they used.
  5.  
    You need to be very careful when comparing these hybrid systems.

    There are some systems which have an air-air heat exchanger, but they bypass this when the ASHP is in use. When the ASHP is running they are effectively exhaust air heat recovery systems & they supply cold air to the house. When the ASHP is not running they become full MVHR systems.

    There are other systems which do not have an air-air heat exchanger at all. An extract air source heat pump heats the domestic hot water when required & only heats the supply air when DHW is not required. So again cold air is supplied to the house when DHW is being heated.

    There are others which wrap the ASHP around the MVHR air-air heat exchanger. So the ASHP extracts heat from the MVHR exhaust & uses this to post-heat the air supplied to the house by the air-air heat exchanger &/or heat DHW.

    The Paul Compakt 360dc is different because it has independent MVHR & ASHP systems. They share common intake & exhuast ducts between the unit & the outside world, but the ASHP does not utilise air extracted from the house & the MVHR air-air heat exchanger is always in use. So the MVHR is always running at full efficiency & performance should be as good as separate MVHR & ASHP units. The key advanatge is that they in effect deliver an integrated heating & ventilation system. The downside is likely to be cost.

    David
    • CommentAuthorDarylP
    • CommentTimeJun 30th 2010
     
    David (and others),

    Thanks for the above. I have not seen the Paul Compact 360dc, but I was hoping that they might do something, as you detailed above.

    I will have a look and do some investigation... :wink:

    Cheers....
    • CommentAuthoralbacore
    • CommentTimeJul 1st 2010
     
    Also Genvex do this with their Combi 185 unit. Pricy, though
  8.  
    The more efficient the HRV unit is, the lower the COP of the heat pump, I would imagine.
  9.  
    Posted By: Viking HouseThe more efficient the HRV unit is, the lower the COP of the heat pump, I would imagine.
    That's true. In addition, some of the units which integrate an ASHP use lower efficiency MVHR heat exchangers to leave more energy in the MVHR exhaust for the ASHP to extract .

    David

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