Air Source Heat Pump

Simoncbevans · 9 March 2009 at 2:58PM

I am interested in hearing from anyone who has had an air source heat pump installed for space heating in their house and who has had it for at least a year, preferably as a replacement for or addition to an existing conventional system.

I am considering fitting one to run alongside my oil fired system (so called "bivalent" system). I am aware that air source is not as efficient as ground source but that they are a lot cheaper to buy. I accept a higher running cost against lower capital cost in principle.

There is a lot of uncertainty at present about quite how effective heat pumps are in practice. The claims are fine, but experience counts! The bottom line is whether people who have them are finding their fuel costs significantly reduced and whether there are any other considerations like maintenance issues.

Any advice gratefully received!

Andy_WSM · 9 March 2009 at 9:37PM

Simon, my gas boiler packed up a year ago, so I took to using my A/C (Air - Air pump) to heat the house (this had already been installed in the Summer) and whilst it was "OK" I found it drafty at times. The running costs though were better than my gas bills. I used to pay ~ £200 for a Winters gas, but the air-air heat pump only cost £180 to run this Winter and it was a lot colder this Winter than previous years. I was however heating water by electric separately and not monitoring the cost of that.

However...As I didn't like the drafty heat from the A/C, just over a week ago I purchased an air to water pump and connected it to my old central heating system and water tank. RESULT! Best investment ever! I have posted some details here: http://forums.moneysavingexpert.com/showthread.html?t=1464827

Summary - I have all radiators on thermostatic valves, The heat pump is set to shut down at 48C (and does so frequently) - room temperatures are set at between 18C & 23C and all are being maintained comfortably. The unit is only 5KW, but the house isn't big and is extremely well insulated, so I don't need a huge amount of heat. Oh, I also leave it on 24/7 so that at no point has it got to work hard to heat the house from cold. I guess if I was only going to run it morning and night I'd need a bigger pump, but I have a chaotic work pattern/life style so 24/7 heat has always suited me best.

Running costs - first impressions are good. The maximum it has cost in a 24 hour period is £2.20, it was -4C out overnight though. Today has been warmer and it has cost £0.66 for the last 12 hours! These costs include a tank of hot water, which is plumbed in as priority over the heating.

My Dad is now looking into a heat pump for his property in Devon where there is no gas available. A 3 bed house would probably need the 11KW unit (or bigger) though.

Hope this helps.

albyota · 9 March 2009 at 11:08PM

Simon, here is a previous post I have cut & pasted to save typing again!

the system I have has developed from a self build I have not quite finished....one day hey..I originally fitted a very efficient oil condensing boiler, which ran very well for two years until the price of oil went up vastly in july / august last year and made the decision to take it out and replace with the ASHP. it was installed at the end of October... I had £700 saved for buying oil as that was the amount we used last winter for aprox 180 days..just for heating and hot water mind... as previously posted my electric bill for nov 6 to jan 25 was for £343...which is for the whole electric useage and roughly £185 of that is for the heating / hot water.. I have meter readings captured daily, and also the outdoor min / max temps. total cost for ASHPB fitted was £2750.

Sladden · 6 August 2010 at 10:35AM

Hi,

I realise that this is my first post so my credability might not be the best but anyway. I've reacently bought a smallish (50sqm) quirky flat that is more like a semi-detached bungalow. Insulation is OK, not good but could have been a lot worse. Heating is solely electrical with no gas in the flat and storage heaters are installed. Now to my point, I'm from Sweden and used to very cold weathers but nicely heated houses. The 'biggest' thing in heating for the last 10 years in Sweden has been air-to-air heat pumps and they are extremely common (think more like no oil or gas is used in Sweden, all new installations are pretty much heat pumps). I notice 2 main differences between the forums in Sweden (which are vary large with thousands of recent posts) and the discussions here. First and foremost PRICE.

Sweden is by no means a cheap country, pretty much everything is more expensive than in the UK. But, an installed Mitsubishi Electric heat pump with one internal unit is never (OK, maybe in very special circumstances) more than £2,000. Here people are talking about £4-5,000+. why is that.

Secondly, people here seem to complain that the unit is not efficient or working when it's cold, hmmm Sweden -20 degrees and my parents 170 sqm detached two story house is heated by a 5kw Mitsubishi unit with ONE internal unit on the lower ground in the stairwell, inside temperature in any room (internal doors open of course) never falls below 20 degrees. How can it differ so much in efficiency? OK, I know that we have 'space age' triple glazing as standard and everything is insulated but I've seen people installing 4 pumps with a internal unit in pretty much every room here... This is not how we use it in colder climates. And also, there seems to be a raliability issue as people are suggesting having a 'back-up' system. Why? I just say.

And after my rant, here is my question. If a buy a unit in Sweden instead (~£1,500) for a Mitsubishi and bring it here, would it be possible to find an installer for it? I'm in Greater London.

I would greatly appreciate any input/comments!

Christia

paceinternet · 6 August 2010 at 11:54AM

Christia, check the electricity supply for the Swedish models. Are they single or 3 phase? 220/240 or 380/415 volt?

Storm20 · 4 September 2011 at 9:02PM

Google says 220-240v so can we continue.

a

Air Source Heat Pump

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