air source heat pumps pros and cons

[djbobbins]

CoP on air source is lower than ground source, from memory max about 2.5 (I.e 2.5 units of heat out for every unit of electricity in).

 

As temperature drops off that will get worse.

 

Depending on your views on carbon and the future carbon intensity of grid power, the basic economics suggest that as power is about two and a half times as much as gas, it's about as cheap to get your primary heat from gas. And a lot cheaper to install.

 

I've heard a few horror stories on air source, mainly as stated above of installations in poorly insulated houses leading to 24/7 pumps running and / or backup heater elements using electricity as primary heat.

 

 

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[Big J]

Pointless eco bling (looks good, but does little to improve your carbon foot print).

 

Far, far better to invest in energy retention than small scale energy creation. Renewables just aren't economical on that scale.

[WorcsWuss]

Pointless eco bling (looks good, but does little to improve your carbon foot print).

 

Far, far better to invest in energy retention than small scale energy creation. Renewables just aren't economical on that scale.

 

I'd agree with that. Our approach is air leakage prevention, insulation, photo voltaics and micro controlled electric heating.

Relatively low install cost, minimal maintenance, low waste. We did 600 student bed sits last summer. This summer we should do more....

[samarb]

I have one and can rate it highly, even covered in snow it worked well. Electric £ is about 1/2 what we were paying in last place. Water is never boiling but hot enough, shower always warm amd heating works well.

[nooie]

We put one in our comunity centre and it seems to work great. It's on 24/7 set at 14 degrees. The bills are a lot lower than they used to be though we also have a lot of insulation in the building. We are close to the sea and it seems you are lucky to get 6 years out of a unit with the salt spray we get. An army base down the road changes them after 4 years! They are nearly on the beach though. I wouldn't have one myself due to what I hear about the salt spray, but it does work well otherwise.

[muttley9050]

Imo avoid like the plague. Expensive pretend Eco heat. For that money you can install a gasification boiler and get

Proper Eco heat.

The whole system is nonsense to me, like leaving a fridge open to cool Ta house down in summer. Just doesn't work. Avoid avoid avoid.

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[Woodworks]

HEAT PUMPS WORK.

 

The problems come from poorly designed systems in badly insulated homes. On the continent they have been using them for many years without any fuss. We have a GSHP it just works with no problems no huge bills it just sits in the corner and does it's thing. Air source is going to be less efficient on the coldest days but will be better in the summer if it used for the hot water.

Edited February 11, 2013 by Woodworks

[spudulike]

My take on it in my own personal situation is you hit the easy bits first - insulate walls, roof cavity, and windows. This will be a long term solution with almost zero upkeep - retain the heat in the house.

 

We got our house walls insulated for £100 - some Government initiative and IMO - well worth the dosh.

 

I collect free wood and would imagine many on here are similar - keeping the log burner fired up in the winter makes a lot of sense - I have contemplated getting a secondary log burner in but fitted with a back boiler to assist the oil fed boiler - to me that more sense.

 

The ground fed heat exchangers look more interesting to me - using the inherent heat from the earths surface to heat your house - know nothing on their efficiency though!

[Big J]

HEAT PUMPS WORK.

 

The problems come from poorly designed systems in badly insulated homes. On the continent they have been using them for many years without any fuss. We have a GSHP it just works with no problems no huge bills it just sits in the corner and does it's thing. Air source is going to be less efficient on the coldest days but will be better in the summer if it used for the hot water.

 

The fact that they do work is not being disputed here.

 

They are however a very inefficient method of heating your home or your hot water. You cite summer usage for hot water, but you would be far better (and it would be much cheaper too) to install solar hot water panels.

 

The very best thing that you can do in this country (apart from demolish your house and start again - we really do live in some of the worst housing in Europe) is heavily insulate your house, sort out your air tightness and for us in the arboricultural industry, install a wood burner/wood fired heating system.

 

My the practice for whom my wife works have been putting up extremely green buildings for over 30 years and they only ever installed one air source heat pump. It was never used.

 

Jonathan

[Woodworks]

Totally agree with insulate,insulate,insulate.

 

"They are however a very inefficient method of heating your home or your hot water. You cite summer usage for hot water, but you would be far better (and it would be much cheaper too) to install solar hot water panels. "

 

Sorry Jonathan can't agree with all of this unless you think 1.7 kWh per day for hot water is expensive. Don't get me wrong solar hot water is very good but almost impossible to do all your space heating with so you then need another system for space heating. The great thing with heat pumps, air and ground sourced is they are capable of doing both from one unit. It would be great if we could all live in Passive houses with no need for heating systems but it's not going to happen in the near future and a well designed heat pump systems is a good solution for some. Today for example I have turned on our GSHP as it running for free with the electricity generated by our solar panels. Recently we added a wood burner not because we were cold but because we were selling logs and it made sense to use them for some of the heating. I did some figures and worked out we would be better off just running the GSHP and selling all the logs. We haven't chosen to because we love the flames from the fire but the figures were clear cut. Heat pumps are not a fix all solution for everyone but a well designed system in a well insulated home is capable of a COP of 4 and that is cheaper to run than mains gas.

Edited February 11, 2013 by Woodworks