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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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Heating and cooling: quick dumb question about air conditioners

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  1.  
    • CommentAuthorRobinB
    • CommentTimeMay 19th 2009
     
    Are they all heat pumps and can they all heat?

    They look cheaper than most ASHPs sold for heating and yet the heat outputs and COPs on them look quite decent.
    Am I perhaps missing some important point? I'm only really interested in heating- I can only imagine about 2 hours a year when I'd like my house to be cooler. I'm kind of hoping that there's an economy of scale in production here and that one about £900 with and output of 5kw would do us.

    I really hope this post doen'st get me a negative tag for mentioning the AS word(s)
    • CommentAuthortony
    • CommentTimeMay 19th 2009
     
    Yes they are all heat pumps (except the evaporative coolers) and no they cant all heat!

    They all can in theory indeed when cooling indoors they heat outdoors but indoor optional heating is not standard and even sometimes costs extra!
    • CommentAuthorRobinB
    • CommentTimeMay 19th 2009
     
    Thanks!
    • CommentAuthorDantenz
    • CommentTimeMay 19th 2009
     
    Yep, heat pumps they are, they pump heat form where it is unwanted to where it's wanted. If you are only interested in heating capacity rather than cooling capacity then choose carefully, look at the relative outputs. Some air to air heat pumps (or air con unit) are designed specifically to be more efficient in heating mode rather than cooling mode and this is usually reflected in the evaporator design in the outdoor unit, ie larger surface area for incresed energy absorption. Check out the Worcester Bosch product.
    • CommentAuthorBuzzfan
    • CommentTimeJun 17th 2009
     
    <blockquote><cite>Posted By: RobinB</cite>Are they all heat pumps and can they all heat?

    They look cheaper than most ASHPs sold for heating and yet the heat outputs and COPs on them look quite decent.
    Am I perhaps missing some important point? I'm only really interested in heating- I can only imagine about 2 hours a year when I'd like my house to be cooler. I'm kind of hoping that there's an economy of scale in production here and that one about £900 with and output of 5kw would do us.

    I really hope this post doen'st get me a negative tag for mentioning the AS word(s)</blockquote>

    Hopefully somebody more technical than I will respond later, but no - aircon heatpumps are NOT the same as heatpump heaters. The broad principle may be similar, but one is designed to cool a house, the orther to heat.

    Apart from the cheapest, most small split aircon systems are "heatpump" inverter units, but you cannot really install the external unit indoors and vice versa, and expect to heat economically. Many have an additional electric coil (heater battery) - when in heatimng mode, the heatpump closes down, and the room's existinmg air is drafn over the battery by a fan - ie they are just glorified electric fan heaters at this point.

    What I cannot understand is how Daikin and others can charge c £ 500 for a split aircon system, and £ 5000 for a heating heatpump- please would any experts advise on this and/or correct any misapprehension above!
    • CommentAuthorRobinB
    • CommentTimeJun 17th 2009
     
    Hopefully somebody more technical WILL post later - in the meantime I'm thinking what you're thinking - economies of scale are maybe making these the more affordable alternative for air to air heat. I am now thinking I want air to water (heating a decent sized thermal store on economy 7, saving money) so a "proper" ashp may be in order.
    • CommentAuthorCWatters
    • CommentTimeJun 18th 2009
     
    Portable air co units are pretty noisy beasts as well.
    • CommentAuthormarktime
    • CommentTimeJul 1st 2009 edited
     
    Splits for heating/cooling have a 4-way valve to reverse operation. A dedicated Aircon won't have the valve. They are tumbling in price and going out the door in great numbers. Here in Madrid you can get 3.4 kw cooling/5.3 kw heating drawing about 1200 watts for around 400 euros fitted (Panasonic PE12CKE). BTW That's air to air.

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