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

Cardew

Excellent post John.

If COP = 2.3 is a fair figure that puts the output at around 5p/kWh.

richardc1983

I am buying a house at the moment... My epc is 73 in the C range with a potential to be 74 in the C range. Wonder what reccomendation there was to get to 74?

John_Pierpoint

This is not really the appropriate thread but it seems that you can get away with putting PV panels on the roof of a "D" house at your risk and then saying now let us redo the "tick the boxes" R-SAP for the EPC and bingo the house now has a "C" rating because it is fitted with solar PV.
But it does make sense forbidding the FiT subsidy to an owner who cannot be bothered to fit £1,000 of energy saving insulation.

lovesgshp

Hi John P.

Just to pick up on your earlier comment:
"As an aside, there was a story circulating that people with a ground source heat pump in drought areas built on clay were in trouble this year.
The rule of thumb for the ground loop is "the wetter the better" . This year the dryness and shallowness of some installations has combined and the clay has shrunken away from the "slinky" ground loop, effectively double glazing it and making the pump work overtime to the stage where it tries to freeze the ground"

We are on heavy clay soil here and had virtually no rain here for 6 months. 2 inch cracks in the ground but no performance loss over the winter. We do not have slinky's though and the ground loops are bedded in sand to reduce that type of situation for clay soil.
If too shallow, then that is a design problem!!

[Deleted User]

Heavy snow since early morning with enough on the ground to make snowmen.

Also feels quite wet in the air so ASHP working fairly hard. Wouldn't want to be a close neighbor of an ASHP as you can hear it from quite a bit away. Some people have said it's like a washing machine on spin but a lower pitch sound which is fairly accurate. We can just about hear it from the inside of the house.

Anyway temp in the house is the the usual rock solid 20c. Don't like it warmer than that. Flow temp is the low 30s so efficiency is still high and running costs very low.

The annoying thing is I'm supposed to be re-roofing some school sheds today [the wife volunteered me] - fat chance in this weather

I could have been sun bathing a few days ago...

lovesgshp

jeepjunkie wrote: »

Heavy snow since early morning with enough on the ground to make snowmen.

Also feels quite wet in the air so ASHP working fairly hard. Wouldn't want to be a close neighbor of an ASHP as you can hear it from quite a bit away. Some people have said it's like a washing machine on spin but a lower pitch sound which is fairly accurate. We can just about hear it from the inside of the house.

Anyway temp in the house is the the usual rock solid 20c. Don't like it warmer than that. Flow temp is the low 30s so efficiency is still high and running costs very low.

The annoying thing is I'm supposed to be re-roofing some school sheds today [the wife volunteered me] - fat chance in this weather

I could have been sun bathing a few days ago...

Unfortunately, ASHP units do have higher noise levels. Probably better though than motorbikes, which do not seem to have silencers over here!!!

mario2013

Cardew wrote: »

Excellent post John.

If COP = 2.3 is a fair figure that puts the output at around 5p/kWh.

2.3 refers to non PCDF listed heat pump products only, the majority of decent ones are on this list and hence will be getting seasonal performance factors much higher and specific to the building in which they are to be installed.

Cardew

mario2013 wrote: »

2.3 refers to non PCDF listed heat pump products only, the majority of decent ones are on this list and hence will be getting seasonal performance factors much higher and specific to the building in which they are to be installed.

Look at page 37 of this document.

http://www.house-builder.co.uk/documents/BR12-DYFRIGHUGHES.pdf

John_Pierpoint

mario2013 wrote: »

2.3 refers to non PCDF listed heat pump products only, the majority of decent ones are on this list and hence will be getting seasonal performance factors much higher and specific to the building in which they are to be installed.

.......one would hope, however..............

Interestingly the CoP for both air and ground source heat pumps to radiators is to be reduced to 1.6 for design purposes.

I think the government is sick to death of supplying subsidies to social housing schemes, that simply don't perform. The real benefits are achieved by good detailing when building high insulation buildings only when that is right does the "eco bling" technology come into its own.
I have in passing locally seen the same old building techniques: "Thermal blocks" with massive thick mortar beds (enough to create patten staining on the inside of the resulting plastered wall) and solar thermal panels, there to comply with "Merton principles", on roofs facing the wrong directions.

I hope the intention is to reserve the bolt on technology and then challenge the finished product to demonstrate that it is achieving the design requirements - and if not the builder can then apply at their expense, the "eco bling" to achieve the design standard.

Here is a thread from relative low income tenants lumbered with unsuitable "heating" they don't understand. It becomes becomes full price electrical heating, with forced ventilation in the depth of winter, with no opportunities to economise.

https://forums.moneysavingexpert.com/discussion/2959648

John.

I visited a building opened last weekend, subsidised by grants, and triple glazed.
However the draught strip on the doors leading out onto the "veranda" had been incorrectly designed/installed and was already failing on the threshold.

This building is heated by a small log stove and a big air source heat pump, it will be interesting to see how it copes next winter.
Do drop in for a coffee and slice of home made cake.
http://blog.danielbridge.co.uk/2012/06/abberton-reservoir-opening.html

mario2013

Very good document this thank you, slide 37 gives 'default' SPFs which have rightly been reduced for untested equipment.

The PCDF incorporates a wide range of heat sources including heat pumps, it gives additional savings in kWh/year for using tested equipment, this can be translated to a SPF, above 3 is achievable with both ASHP and GSHP.