Ground and Air Source Heat Pumps

[Skyedriver]

With a new oil combi, pipework and tank needed I am wondering about the options of a Ground or Air Source heat pump. Now I don't really fully understand them, know the ground one requires a borehole or large field and the air one is a bit noisy and stops working when it gets really cold.
So: with the supposed Government incentives (are they still available with this new govt) is it worth considering. I guess revamping the oil set up at £5 to £7k all in, what are the installation costs of GSHP & ASHP and what are the drawbacks. Finally anyone in the Yorkshire area fit these things to discuss with??
Thanks Guys

[Melchett]

This may help, I had a similar question a while back:

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[NDA]

Many new build swimming pools are, I hear, choosing air source heat pumps instead of boilers.... Just as effective and, with oil and gas being mahooosively expensive, a sensible choice.

[caziques]

Sorry, rather a long way from Yorkshire - but I do know about heat pumps.

Your basic problem will be the existing radiators, which probably have something like 60 degree water going to them, 50 degree water coming back.

Asking a heat pump, ground source or air source, to heat water from 50 to 60 is not a good idea. The efficiency will be very low.

Heat pumps can often be a very good solution to a problem, unfortunately trying to convert a conventional radiator system will generally not work very well - you really need to double the size of the radiators.

[GetCarter]

Hi Tony

/\ What he says I think. We went with ground source, but it made sense in a new build. Converting existing house to heat pump not usually viable.

[Skyedriver]

[quote=GetCarter]Hi Tony

/\ What he says I think. We went with ground source, but it made sense in a new build. Converting existing house to heat pump not usually viable.[/quote

Hello Steve
How are you, keeping, well I trust. How is Shieldaig?
Seems a long way from where I am now, temporary accom at the in-laws, near Tyneside, renovating a house in Yorkshire, working in Darlington.
I do miss the rain and the midgies and I never thought I'd say that. Also miss the scenery, clean air and relatively traffic free roads. Still have our home on Skye, need to call back up to collect some tools....and cut the grass.
Anyway thanks for the comments, guess its back to conventional heating and hot water.
Keep dodging the campervans...... and deer
Tony H

[Ken Sington]

caziques said:

Sorry, rather a long way from Yorkshire - but I do know about heat pumps.

Your basic problem will be the existing radiators, which probably have something like 60 degree water going to them, 50 degree water coming back.

Asking a heat pump, ground source or air source, to heat water from 50 to 60 is not a good idea. The efficiency will be very low.

Heat pumps can often be a very good solution to a problem, unfortunately trying to convert a conventional radiator system will generally not work very well - you really need to double the size of the radiators.

Would it be viable to use an air source heat pump to act as a pre-heater in combination with an existing oil fired system, so that the pump takes the water up to a certain temperature, thus reducing the load and hence the oil consumption of the current system?

[caziques]

Ken Sington said:

caziques said:

Sorry, rather a long way from Yorkshire - but I do know about heat pumps.

Your basic problem will be the existing radiators, which probably have something like 60 degree water going to them, 50 degree water coming back.

Asking a heat pump, ground source or air source, to heat water from 50 to 60 is not a good idea. The efficiency will be very low.

Heat pumps can often be a very good solution to a problem, unfortunately trying to convert a conventional radiator system will generally not work very well - you really need to double the size of the radiators.

Would it be viable to use an air source heat pump to act as a pre-heater in combination with an existing oil fired system, so that the pump takes the water up to a certain temperature, thus reducing the load and hence the oil consumption of the current system?

Heat pumps are supreme at heating water from cold up to say 50 or even 60 degrees, however they are not designed to maintain water at high temperatures - which is what conventional heating systems do.

ie the cool water going back to a boiler will still be at say 50, oil or gas has no problem getting it back to 70, a heat pump does.

Taking water from 25 to 35 on the other hand is where a heat pump is superior to ALL other heat sources (as they can easily put out 5 units of energy for every 1 consumed) - these conditions are found in underfloor heating systems and swimming pool heating - hence heat pumps are the number one choice for these.

The choice of air or ground source depends on various factors - in NZ air source is the most cost effective as most underfloor heating can be done in the day when it's never below freezing. If there is one thing I don't miss about the UK it's those mid day temperatures of minus 5, under these conditions ground source is better, but a lot more expensive.

Heat pumps are not the same as any other source of heating, basically the efficiency is dependent on the temperature difference you are trying to pump between - the closer they are the higher the efficiency.

I can heat a 200 sqm house here in New Zealand with a 12kW heat pump drawing 2kW - in the middle of winter this will be running about ten hours a day - yep, a whole house heated with less than a fan heater.

Edited by caziques on Thursday 27th May 22:05