Dummies guide to COP?

Exiled_Tyke

Reed_Richards said:

shinytop said:

I'd have liked a GSHP but they are a lot more expensive and disruptive to install. 

Although GSHPs achieve better SCoPs that ASHPs, there must be times when the air temperature is higher than the ground temperature and the ASHP is the more efficient of the two.  What I would like is a system that combines both and selects whichever is the more efficient to run.  AFAIK that's something you cannot buy!

As ground temperatures remain relatively constant I can't see the need for such functionality. So there will be times when air temperature is higher, but these are the times when homes need relatively less heating.  I can't see the additional cost over a standard GSHP being recoverable by adding an ASHP to the system. 

JKenH

Reed_Richards said:

shinytop said:

I'd have liked a GSHP but they are a lot more expensive and disruptive to install. 

Although GSHPs achieve better SCoPs that ASHPs, there must be times when the air temperature is higher than the ground temperature and the ASHP is the more efficient of the two.  What I would like is a system that combines both and selects whichever is the more efficient to run.  AFAIK that's something you cannot buy!

Something I had been thinking about was combining either an ASHP or GSHP central heating system with the two wall mounted ASHPs (let’s call them aircon units to avoid confusion) I already have. Combined with the GSHP it would give me the option to just use the aircon units on their own on mild days which is what in fact I have been doing for virtually the whole of the last month (including several frosty mornings over the last few days) but with the fall back option of the GSHP for the colder weather. This might allow me to go for a cheaper GSHP installation using my existing radiators and supplement the heating when required with the aircon units. Or I could risk an ASHP with the existing rads plus  the aircon units. (We have a largish house and do not need to heat all the rooms to liveable temperatures all the time. I also have an open fire and limitless supply of my own firewood).