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

Hermann

matelodave said:

Here you go, a website with some data on actual installations - https://heatpumpmonitor.org/

It's obviously compiled by those who have put quite a bit of effort into monitoring their system performance and TBH I'm not sure how rigorously it's been collected but it does give some idea of what is possible, probably by those who've put a some effort into tweaking and optimising their systems.

If you go to the links (on the right of the table you can see the monitor outputs and there is a forum, albeit a bit skewed towards the Open Energy Monitor but there may be some hints and tips - https://community.openenergymonitor.org/c/hardware/heatpump/47

Haven't looked into the fine details but interesting to see that the stated COP achieved varies from 2.6 to 4.4.
That's quite a variation and possibly shows how difficult it is to establish the running costs/efficiency for any particular installation in advance.

matelodave

Hermann said:

matelodave said:

Here you go, a website with some data on actual installations - https://heatpumpmonitor.org/

It's obviously compiled by those who have put quite a bit of effort into monitoring their system performance and TBH I'm not sure how rigorously it's been collected but it does give some idea of what is possible, probably by those who've put a some effort into tweaking and optimising their systems.

If you go to the links (on the right of the table you can see the monitor outputs and there is a forum, albeit a bit skewed towards the Open Energy Monitor but there may be some hints and tips - https://community.openenergymonitor.org/c/hardware/heatpump/47

Haven't looked into the fine details but interesting to see that the stated COP achieved varies from 2.6 to 4.4.
That's quite a variation and possibly shows how difficult it is to establish the running costs/efficiency for any particular installation in advance.

As I said, its hard to know just how rigorous some of these are, I'd really want to know the actual set up of the measuring kit.

Especially whether they are using calibrated heat meters (like the ones for measuring RHI) or just relying on data sucked out of the heatpump itself as I guess there could be a wide variation in accuracy between the two.

However it does give you some idea of what might be possible if you've got a properly configured system although I'm sure that the average family wouldn't be quite so finicky. Likewise we all use our systems differently so run it for 24hrs a day whereas others might only heat for a couple of hours in the mornings and evenings

If you click on the little square on the left you get a bit more info on the system parameters

AntonyTewks

Hiya

Had a suggestion to pop my query on this thread - we've had a heat loss survey come out at 5.1kw at -2, sounds about right - in winter we've range rated boiler to 5.2kw and that's kept us warm even when below 0 outside.

Because of the cold winter they've suggested an 8.5kw heatpump, but there's also the option of a 6kw. I'd think the 6kw would be sufficient and prob more efficient overall. Any thoughts?

richardc1983

AntonyTewks said:

Hiya

Had a suggestion to pop my query on this thread - we've had a heat loss survey come out at 5.1kw at -2, sounds about right - in winter we've range rated boiler to 5.2kw and that's kept us warm even when below 0 outside.

Because of the cold winter they've suggested an 8.5kw heatpump, but there's also the option of a 6kw. I'd think the 6kw would be sufficient and prob more efficient overall. Any thoughts?

Lots of factors, air 2 air or air 2 water, what spec of units are they suggesting do you have any data? 

AntonyTewks

Ecodan, Air to Water. I've been looking through the databook and it doesn't seem like the 8.5 offers any better performance at lower temperatures than the 6, and the 6 seems to offer consistently better COPs, I'm thinking if my heatloss is 5.1 then 6 is the best match

Reed_Richards

If you use your heat pump to heat your hot water tank then when it is doing that it isn't heating your house.  So if, for example, it spends 10% of its time heating your hot water it only has 90% to heat your house to a model with a 6 kW output would only give you 5.4 kW of heating power.  The smaller the power of your heat pump the longer it will take to heat your hot water tank .

The maximum output power is important on rare times of really cold weather but most of the time the heat pump will only need to run at some fraction of its maximum output.  It will run most economically if it uses just enough power to heat your house continuously, rather than running in on/off cycles.  Therefore the minimum power that your heat pump will run at is very important.      

AntonyTewks

Reed_Richards said:

If you use your heat pump to heat your hot water tank then when it is doing that it isn't heating your house.  So if, for example, it spends 10% of its time heating your hot water it only has 90% to heat your house to a model with a 6 kW output would only give you 5.4 kW of heating power.  The smaller the power of your heat pump the longer it will take to heat your hot water tank .

The maximum output power is important on rare times of really cold weather but most of the time the heat pump will only need to run at some fraction of its maximum output.  It will run most economically if it uses just enough power to heat your house continuously, rather than running in on/off cycles.  Therefore the minimum power that your heat pump will run at is very important.      

Waters going to be separate so should be less of a strain and yes plan to run continuously on weather comp. The efficiency of the 6kw looks a fair bit better than the 8.5kw so prob going with the 6 and will supplement if it gets far below design temp