UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

Reed_Richards

Cardew said:

In the Brochure they give the comparative fuel costs for a 4 bed house. The low temperature heat pump has annual running costs of £571, the high temperature heat pump has an annual running cost of £978 i.e.71% higher.

Radiators are not very expensive if you avoid the "designer type".   They are generally easy to remove and replace and if the ones you have at present are one or two panel then you could probably get finned replacements of much the same area.  If you can save £400 per year in running costs then you will quickly pay for the cost of new radiators and if your heat pump has a better CoP you will get more money from the RHI.   

Cardew

Reed_Richards said:

Cardew said:

In the Brochure they give the comparative fuel costs for a 4 bed house. The low temperature heat pump has annual running costs of £571, the high temperature heat pump has an annual running cost of £978 i.e.71% higher.

Radiators are not very expensive if you avoid the "designer type".   They are generally easy to remove and replace and if the ones you have at present are one or two panel then you could probably get finned replacements of much the same area.  If you can save £400 per year in running costs then you will quickly pay for the cost of new radiators and if your heat pump has a better CoP you will get more money from the RHI.   

Also the saving of £1,599 in the higher purchase price will pay for a lot of radiators!

matelodave

Have a shufti here - the high temperature heatpumps have a COP nearer 2-2.5whereas conventional low temperature units tend to be spec'd at nearer 3.5-4. https://www.theheatinghub.co.uk/articles/high-temperature-heat-pumps

Bear in mind that as very few people get anything like the spec'd COP then you can expect that a high temperature unti wont be everso cheap to run.

They may sound like a good idea but the extra cost of one over a low temperature unit and the higher annual running costs would buy lots of new low temperature radiators. And as R_R points out you'd get more back in RHI payments.

I'm guessing that the reason there's not much info around is because they aren't very popular

shinytop

With the new cap and a gas boiler efficiency of 80% I reckon heat pumps are now a leading by about a head. A nose at least... 

Cardew

shinytop said:

With the new cap and a gas boiler efficiency of 80% I reckon heat pumps are now a leading by about a head. A nose at least... 

Fair comment if your Heat Pump can achieve a little over a system COP of 3.0 - taking into account you won't need to pay the gas Daily Standing Charge(unless you cook with gas)

The problem in this mad world of ever changing energy prices the next price cap in Oct could skew prices to increase electricity by a greater percentage than gas or vice versa.

richardc1983

Cardew said:

shinytop said:

With the new cap and a gas boiler efficiency of 80% I reckon heat pumps are now a leading by about a head. A nose at least... 

Fair comment if your Heat Pump can achieve a little over a system COP of 3.0 - taking into account you won't need to pay the gas Daily Standing Charge(unless you cook with gas)

The problem in this mad world of ever changing energy prices the next price cap in Oct could skew prices to increase electricity by a greater percentage than gas or vice versa.

I read today they are expecting another 45% increase at least come October.  

shinytop

Cardew said:

shinytop said:

With the new cap and a gas boiler efficiency of 80% I reckon heat pumps are now a leading by about a head. A nose at least... 

Fair comment if your Heat Pump can achieve a little over a system COP of 3.0 - taking into account you won't need to pay the gas Daily Standing Charge(unless you cook with gas)

The problem in this mad world of ever changing energy prices the next price cap in Oct could skew prices to increase electricity by a greater percentage than gas or vice versa.

I'm averaging well over 3.0 over the winter so far.  No gas here either.  But yes, who knows where we'll be in a year's time. 

hebridean

I’ve presently got a 11kw Grant Aerona that I had installed eleven years ago in a new build. I’ve installed four replacement soft starter units in this time and today it’s gone on the blink again which will probably be another soft starter. They seem to be needing replaced almost annually now and cost around £250 a pop. 

Given it’s age and it’s ailment I’m now thinking of having a new one installed, maybe a 11.2kw Mitsubishi which seem to be well reviewed and durable. Would I be wrong in thinking it’s just a matter of connecting the new unit to the connections left by the old unit? Can I use the same unvented hot water tank? I do think I’ll need to use the new unit’s indoor programmer that links to the ufh and hot water demands. I’d be grateful for any thought on my situation.

Reed_Richards

I have wondered about what will happen when I find myself in a similar situation ten years (or so) from now.  There is a manufacturer's unit stuck to the side of my HW tank so the heat pump controller can control the immersion heater; that would probably need to go if I changed manufacturer for my next heat pump.  There must also be a thermocouple measuring the tank temperature but those are generic, provided you can set the thermocouple type in software to match what is there.  So I don't expect to need a new hot water tank, nor any new pipework.  I have a mono-block unit (everything is outside) so hopefully I will just need to change that and the indoor controller.    

hebridean

Yes Reed exactly what I’m hoping is the case.