Air Source Heat Pumps

[classybird]

Does anyone have knowledge or personal experience of Air Source Heat Pumps? A company who did some work for me previously contacted me and sent someone round RE these. I have absolutely no knowledge of these hence why I'm here. Basically it costs 13k (spread over 7 years on finance) to install, but apparently you get back an equivalent amount from the government over the next 7 years, plus the money that you save each month on your gas bill. They wi also replace some radiators that need doing, which some of mine do. This sounds like a bit of a no brainer to go ahead with this, if you are getting the money back what is there to loose right. Are they any good, efficient etc? Just asked a friend who has some knowledge of these who said that he wouldn't touch with a barge pole and has heard of where people are suddenly spending an arm and a leg on their electricity instead (like more than they were in the first place on gas). Anyone got anything to share. Thanks lovies!

 

[classybird]

*'to not go ahead with this'

 

[endecotp]

Do you have somewhere suitable for the external gubbins?
Will the noise annoy you and/or the neighbours?
How often does it get very cold (i.e. well below zero) where you are? (Efficiency drops in low temperatures, i.e. exactly when you want most heat.)
Are your radiators generously sized for the rooms? (The water it circulates tends to be cooler than you get from a gas boiler, so the radiators need to be bigger.)

If all of that is OK, it will reduce your energy consumption and hence your CO2 emissions - but the energy you consume will now be electricity rather than gas, and that is much more expensive. I'd expect your total energy bills to remain about the same.

 

[muggles]

They get progressively less efficient the colder the weather gets, and only work well with super-insulated houses. I wouldn't have one.

 

[stem]

Heat pumps can't produce a very high temperature (around 45 to 50 degrees) so are only really suitable for buildings with high levels of insulation. They are normally used with either wet underfloor heating, or ducted air systems.

The insulation is essential, because in cold weather the heat loss must be minimal, or they won't be able to cope. It's also usual to leave them running 24/7 too, because they may not be able to catch up on their own if the fabric of the property is allowed to cool.

If you try to use them with traditional radiators, the radiators will only get lukewarm.

Heat pumps can provide some heat input into a system with traditional radiators, but an additional heat-source will need to operate with it, not only to achieve a satisfactory comfort level, but to make sure that the temperature gets up to above 60 degrees to prevent the risk of legionella if there is stored hot water.

Heat pumps also become less efficient as the temperature drops. This can be very significant with 'air source' because the outdoor units are prone to freezing when the ambient temperature drops below 5 degrees and continually have to defrost themselves. The ground stays warmer as you get below the immediate surface, so this is not a problem 'ground source' heat pumps.

Personally if I had a very well insulated property with wet underfloor heating throughout and a big enough garden to accommodate the required underground pipework , I would consider a ground source heat pump. But I think it will cost a fair bit more than the figures you suggest, and then there's the installation of UFH to add if it's not there already.