Air Source Heat Pumps

[noTAGlove]

My current COP is around 2, not the 4 I would like but I’m very happy with the system.

This is the crux of the matter. Even with a gas boiler not achieving 100% efficiency, with a COP of 2 and leccy costing 4 times more than gas per kWh, utility bills are going to be double that of running a gas boiler. This will be a huge additional cost to the owner (think +£2k/yr)

If the Goverment want mass take up of ASHP then they should invest to reduce the price of electricity (and more importantly the spread of gas to leccy price per kWh). The £7,500 grant is just a gimmick.

[MonkeyBoy]

This is the crux of the matter. Even with a gas boiler not achieving 100% efficiency, with a COP of 2 and leccy costing 4 times more than gas per kWh, utility bills are going to be double that of running a gas boiler. This will be a huge additional cost to the owner (think +£2k/yr)

If the Goverment want mass take up of ASHP then they should invest to reduce the price of electricity (and more importantly the spread of gas to leccy price per kWh). The £7,500 grant is just a gimmick.

This is why I stressed that you get a proper heat survey done. The friend of a friend engineer did my calculation off a plan and massively over calculated by a factor of 2. With a properly sized heat pump I’m sure my COP would be nearer 4.

However I would be the first to admit that heat pumps don’t suit all properties.

[noTAGlove]

With a properly sized heat pump I’m sure my COP would be nearer 4.

You can’t change the laws of thermodynamics, and this is where people need to do their homework.

With mid winter temperatures you are never going to get a COP much above 2.5 whatever system you install.

COP of 4 is achievable in very mild conditions, and a time when you switch the heating off!