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Ground source heat pumps v. air source heat

Home Forums Heat & Hot Water Ground source heat pumps v. air source heat

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  • June 29, 2008 at 8:36 pm #3934

    Barney
    Subscriber

    Looking on the site about ground source heat pumps it says that cost of installation is comparible. I have been quoted £16000.00. This is much more than a traditional heating system. We are also looking at the air source pump. We have been told that the gound source heat pump is the most efficient but are also looking into the air source option coupled with air exchange. Can you enlighten me further. Would be interested in other comments which may be helpful.

    Barney

    June 3, 2009 at 8:03 am #5437

    Katy
    Subscriber

    Hi Barney,

    We are also doing a barn conversion and have been quoted about the same for a ground source heat pump and this is without installation!

    I would be interested to learn ho you have got on with your project and what route you ended up taking. I have found it hard to find the information I need to mak a decision as all the heat pump suppliers are quite guarded or try to hard sell me when I ask about costs.

    Thanks

    Katy

    June 30, 2010 at 3:49 pm #5438

    Amgen Renewables
    Subscriber

    Amgen Renewables http://www.amgenrenewables.com specialise in the design, supply and installation of a range of reneweable technologies such as solar photovoltaics, solar thermal hot water systems and air and ground source heat pumps. Supply and installation of a large single phase heat pump will be a lot less than £16k. PLease feel free to contact us should you have any queries info@amgenrenewables.com

    April 22, 2012 at 2:27 pm #5439

    johnrush
    Subscriber

    Hi Barney and Katy,

    This post may be late for your own purposes but for others who have the same decision to make I would comment as follows:

    Air source heat pump capacity is based on the standard outside ambient temperature of 7C and at this temperature they are relatively efficient having a COP of around 3.5 (i.e. 1Kw electricity produces 3.5Kw of heat, electric fire COP is 1) which makes them slightly more cost effective in energy terms than a gas boiler. The difficulty arises when the temperature falls below 7C, where the heat pump has to spend time defrosting and the COP reduces until at approx -15C (I think) the COP is 1. So if you intend to use it at 7C or above it will be perfectly suited to your needs. If you want it to switch on early on a winters morning ready for waking then there will be times when the efficiency is much less that say gas heating.

    Ground source heat pumps work in a much more forgiving environment as they use water pumped around underground pipes which are not as affected by ambient temperatures. At the correct depth the earth temperature is unlikely to be less than say 11C and this condition allows a temperature of return water of say 9C which is then cooled by the heat pump to 5C extracting the heat in the process. The water is returned underground to be warmed from 5C to 9C and the process continues. There are no defrosting issues with this system and the COP can be 5 and above making them much more energy efficient than gas or air source.

    It is always important with either method to use as low an hot water heating temperature as possible in order to maximise efficiency and keep the heat pump operating in a comfortable environment. This means having a high standard of house insulation and using large areas of heat transfer in the rooms, such as underfloor heating. Radiator systems would not normally be suitable as the higher temperatures required sacrifice heat pump efficiency.

    I hope this helps.

    John.

    Chartered Building Services Engineer

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