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Where to locate an air source heat pump

Topics associated with Air Source Heat Pumps (ASHP) and Ground Source Heat Pumps (GSHP).

Where to locate an air source heat pump

Postby Kevin P » Sun Feb 27, 2011 9:46 pm

Hi,

Does the location of an air source heat pump have any effect on performance? Is it better if it is north facing? Sheltered from the wind etc? Would its performance be adversely affected by being in the shade? I'm working on the principle that since the higher the surrounding air temperature the more heat it can produce then placing it in direct sunlight but sheltered from the wind would be ideal but is this correct?

Thanks

Kevin
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Re: Where to locate an air source heat pump

Postby nrg-steve » Mon Feb 28, 2011 11:56 am

Sufficient space is required for airflow into the ASHP and raised off the ground to prevent showfall/leaves blocking the air to the unit.

Access is also needed for service and maintenance.

If possible the unit should be sheltered from high winds to improve efficiency by reducing the fan power requirement.

ASHP that are only for heating or primarily heating are best placed in a south facing aspect to gain maximum benefit from the (relatively) higher ambient air temperature.

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Re: Where to locate an air source heat pump

Postby Kevin P » Tue Mar 01, 2011 9:01 pm

Thanks for this, another though occurs though. If it's below zero outside, as of course it often is in the UK in winter, especially, after dark, would an ASHP actually produce any heat?

Thanks
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Re: Where to locate an air source heat pump

Postby nrg-steve » Tue Mar 01, 2011 9:05 pm

Yes; the ASHP will produce heat at below zero degrees. The ASHP is though obviously more efficient at say 6 degrees than minus 6 degrees.

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Re: Where to locate an air source heat pump

Postby Colin S-C » Tue Mar 01, 2011 9:27 pm

Don't they work upto -15 degrees?

I recently assessed a house for an EPC with two ASHP units in the loft, they were under normal conditions perfectly capable of providing all the heating and hot water for a quite large four bed detached house but couln't cope in the extreme cold we had in December.

As a back up the installer had linked in a dry core electric boiler ( for cheapness of supply I suspect ) and it had to cut in during that cold spell a fair bit leading to a much higher electric bill that month. He'd also put in all the connections for solar to be installed anytime in the future!

The owners were extremely pleased with their ASHPs, they previously had storage radiators and had the ASHPs fitted two years ago.

They had managed to get away with radiators rather than underfloor heating, I was surprised that the radiators weren't really that much bigger than normal, each room also had it's own thermostat meaning they could heat where required.
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Re: Where to locate an air source heat pump

Postby nrg-steve » Wed Mar 02, 2011 9:17 am

Don't they work upto -15 degrees?


Largely depends on the type of refrigerant used.

They had managed to get away with radiators rather than underfloor heating, I was surprised that the radiators weren't really that much bigger than normal


CWI and Double Glazing will help in keeping the radiator sizing more reasonable.

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Re: Where to locate an air source heat pump

Postby niallmac » Wed Mar 02, 2011 9:31 am

I was horrified to read of two air source heat pumps being located in a loft.

This is an example of the total lack of understanding that exists as to how heat pumps work efficiently.

The thread started with discussion as to whether a unit should be located in a North or South facing location, which is fair enough. In truth neither make much difference. What does matter, however, is the volume of air that passes through the heat pump, is cooled and released back into the atmosphere. Even a relatively small unit will process hundreds of litres of air every hour, so if tghis is in an enclosed space like a loft, and you can forget the idea of there being adequate ventilation, the area will quickly be cooled and the same air will be recycled and cooled further. Before you know it the loft feels like the inside of a fridge.

Wait a minute, isn't that exactly what you've created!
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Re: Where to locate an air source heat pump

Postby Colin S-C » Wed Mar 02, 2011 10:56 pm

niallmac wrote:I was horrified to read of two air source heat pumps being located in a loft.

This is an example of the total lack of understanding that exists as to how heat pumps work efficiently.

The thread started with discussion as to whether a unit should be located in a North or South facing location, which is fair enough. In truth neither make much difference. What does matter, however, is the volume of air that passes through the heat pump, is cooled and released back into the atmosphere. Even a relatively small unit will process hundreds of litres of air every hour, so if tghis is in an enclosed space like a loft, and you can forget the idea of there being adequate ventilation, the area will quickly be cooled and the same air will be recycled and cooled further. Before you know it the loft feels like the inside of a fridge.

Wait a minute, isn't that exactly what you've created!


Hi

I went to Ecobuild today and spoke to a few heat pump people, as you said everyone was horrified at the situation I explained. The problem is, even though I will go back to the owner, they are selling the property and might not be interested in finding a solution or even about being made aware of the problem!
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Re: Where to locate an air source heat pump

Postby Kevin P » Sun Mar 06, 2011 2:23 pm

Hi,

Sorry if this isa silly question (I'm not in the industry) but so what if the loft is as cold as a fridge? What problems does this create?

Thanks

Kevin
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Re: Where to locate an air source heat pump

Postby nrg-steve » Sun Mar 06, 2011 4:10 pm

Poor efficiency by the heat pump and so higher electricity bills will result...

The increased air turbulence and/or air pressure changes in the loft may have a long term effect on the roof structure integrity although I haven't sen or heard of this happening.

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