Using air conditioners as air source heat pumps

Matthew_Pollock

Fitting an air source heat pump on our terrace has been suggested to us, given that our storage heaters can't cope in winter, and our main room is often below 18 degrees, which is uncomfortable. Electricity costs for our 90 sq. m. flat are now £60/month in summer (covering water heating and cooking) and £220/ in winter (adding storage heater costs to the previous costs).   The air conitioner sales person suggested installing a Daikin 3.5 kw aircon unit on our terrace to provide the heating. He said: "Seasonal efficiency for the above system is approx 5.10kw’s output for each 1kw of input,"  with total installation costs of £2,400 for a floor-standing system and £1,680 for a wall-mounted system.

However when I researched air source heat pumps, the installation costs often seem to be quoted at £10,000 and up.

This is puzzling.  The air-conditioning units we have been offered are said to be air source heat pumps.  So are the more expensive air source heat pump solutions.  Why the huge difference in cost and what am I missing? 

tacpot12

Some ASHPs are designed to heat a whole house, and to heat water for baths, showers, etc. Such ASHPs need to have a greater heat capture capability, a thermal store, pumps, plate heat exchangers, etc. Your quote for a single air-conditioning unit is about right. Your unit will only heat a couple of rooms, but they certainly work. I would take the seasonal efficiency figure with a pinch of salt, but it's definitely going to be a good deal cheaper than storage heaters.  

Aircon system with the ability to heat have been around for many years, but haven't been popular in the UK. The manufacturers have started to rebrand them ASHPs, because that is what the are. Previously they've just been called air-conditioning units because people generally bought them for their cooling ability, rather than their heating capability. My daughter's small house in Denmark was heated with exactly the same sort of system as you have been quoted for, and it was able to heat it very comfortably. Remember that heat rises and you don't want the bedrooms to be too warm. You might find you need a thermostatically controlled radiator (with a timer) in the bedrooms for the coldest days in the winter, but I would definitely put off buying these until you are certain you need them. They are cheap, efficient (for occasional use) and readily available. 

Ectophile

Did he say in which season you'd get 5.10kWh out for 1kWh in - a COP of 5.10?  Because that sounds like wishful thinking in the depths of winter.  The colder it is outside, the harder it gets to suck any heat out of the air.

michaels

I think the air-air units do typically have a higher COP but that sounds optimistic (considerably) over the entire year.  The other advantage of air to air over 'air to water' (over being much cheaper if heating a single room) is they can also cool in the summer.  Disadvantage is they do not qualify for any govt incentives which is why (a) they are probably cheaper and (b) installers are generally less interested in them

ASavvyBuyer

I suggest you find out which model they are proposing and then check the actual specification.

I just had a quick look and found the following spec for a 3.5kW Daikin unit.

https://www.daikinairconditioning.com/global/media/pdf/1573122899-2534.pdf 

That does not have a specified SCOP of 5.1 and is only A+ rated.

To get higher SCOP's they need to be A+++ rated for heating. Like the following:

https://www.saturnsales.co.uk/images/products/editor/Fujitsu_R32_Designer_Wall-compressed.pdf

Also, check that the model they suggest is R32 coolant, as other types can cause more CO2 if accidentally released and are apparently more expensive to get re-gased  if needed.

Cardew

Matthew_Pollock said:

However when I researched air source heat pumps, the installation costs often seem to be quoted at £10,000 and up.

This is puzzling.  The air-conditioning units we have been offered are said to be air source heat pumps.  So are the more expensive air source heat pump solutions.  Why the huge difference in cost and what am I missing? 

There are two types of ASHP.

Your quote is for an Air to Air heat pump. So it blows hot, or cool, air into the room.

Most ASHPs heat water that is pumped to large radiators or underfloor heating and to your hot water tank.

For the price you have been quoted it would appear that it will have a single output - you can get multiple output systems.

One issue can be the noise from the unit annoying neighbours(and yourself)

 

ed110220

Apart from not being able to heat hot water, and a traditional preference for water/radiator heating systems in this country, what is the advantage of an air to water heat pump? The disadvantages are obvious - more work, cost and disruption installing/changing larger radiators, slower heating up. Air to air is much simpler, cheaper and probably quicker responding. Is it less efficient?

mickyduck55

michaels said:

I think the air-air units do typically have a higher COP but that sounds optimistic (considerably) over the entire year.  The other advantage of air to air over 'air to water' (over being much cheaper if heating a single room) is they can also cool in the summer.  Disadvantage is they do not qualify for any govt incentives which is why (a) they are probably cheaper and (b) installers are generally less interested in them

I can confirm no one is interested in fitting these systems in my area... filled in numerous online requests and no response unless they make the mistake thinking I want "air to water"... I then get an initial call with a promise to get back to me after I have explained what I want and never hear from them again.. Farnham Surrey

Coastalwatch

Hi MD don't know if the link below might help. They cover Surrey and their prices appear fairly competitive too.

https://www.cooleasy.co.uk/professional-installations

mickyduck55

Coastalwatch said:

Hi MD don't know if the link below might help. They cover Surrey and their prices appear fairly competitive too.

https://www.cooleasy.co.uk/professional-installations

Thank you I have sent them an email....

ASavvyBuyer

When we had our first one installed, we had difficulty finding a local installer (they were all busy with bigger jobs) so we had to look further afield. For the second one, we found a couple of local installers that were able to quote and would be able to fit within a month. Total cost for each was about £1,500 and that included a pump fitting for the kitchen unit as the drain pipe had to go up and out via the loft.

Regarding noise, for ours you need to be within 2-3 metres to be able to hear them, even when running at higher settings. Most of the time they can't be heard. If you go for higher spec models, which tend to be more efficient, they also tend to be quieter than the cheap models some have experience of.

We are very pleased with ours, since being fitted our gas consumption has more than halved and looks like it will be less than a third, of what it used to be, by the end of this winter.

PS: If you are over 60 and you get the same company to supply & install the VAT rate is 5% instead of 20%.