EPC rated air pump as "poor"

Baxter100

Performance data from a recent heat pump installation project:

Electrification of Heat - Interim Heat Pump Performance Data Analysis Report - Energy Systems Catapult



As you can see the SPF varies significantly depending on the individual installation. If you have the installation with the SPF of 4, great, you are matching a gas boiler.

If you've got the system with the efficiency of 2, not so much.

matelodave

Where I live in the Eastern Region gas is 31p/day plus 5.96/kwh whereas leccy is 50p/day plus 25.29p/kwh making leccy over four times the price of gas so you'd need to achieve an SCOP of well over four for a heat pump to cost the same as a gas boiler.

as shown above most seem to be getting around 2.5 to 3.5 with a few who run their systems with lower flow temps managing a little bit better. To manage with those lower flow temperatures you need either underfloor heating or suitably sized radiators.

I guess I'm getting around 3 but its not easy to measure unless you've got a proper monitoring system set up.  My system is pretty old at 14 years, so doesn't have more sophisticated controls or monitoring which I've no doubt are incorporated into newer systems.

However they do need to be specified, installed and commissioned correctly and well. However, and most importantly, users need to understand how they work and how to use them to get the best out of them and so need proper instruction by the installers before they walk off site. There's lots of info in t'interweb but a lot of it can be confusing and there is a lot of negative folklore floating around. 

IMO its those who take the time to understand their systems and get their controls tweaked properly who are happy with the performance and comfort although I'm not sure that anyone will be totally satisfied with the running costs until the price of leccy gets a lot closer to that of gas.

Strummer22

You do get a slightly better outcome for heat pumps when you account for boilers not being 100% efficient. Point taken though and the comparison changes with time as gas and electricity prices don't move exactly in sync.

silverwhistle

matelodave said:

Where I live in the Eastern Region gas is 31p/day plus 5.96/kwh whereas leccy is 50p/day plus 25.29p/kwh making leccy over four times the price of gas

I'd forgotten how expensive the standard rate of electricity is. The situation gets more complicated for some people when we start to consider EVs, solar panels and time of day tariffs. With an EV on Octopus Agile the average rate per kWh on my last bill was 8.31p per kWh, although that was impacted by the very strong winds and cheap rates at the start of the month. This month I'm guessing I'll end up paying about 16p. Previously I was on Octopus Intelligent where my average worked out at ~15p. 

If you can heat water or weight heat pump usage to cheaper times then the raw price you quoted can be bettered. I also have solar panels which make a small contribution to hot water in winter but means I use no gas for 7 months of the year. I'm contemplating going the A2A route and coming off gas completely.

Jemma01

silverwhistle said:

matelodave said:

Where I live in the Eastern Region gas is 31p/day plus 5.96/kwh whereas leccy is 50p/day plus 25.29p/kwh making leccy over four times the price of gas

I'd forgotten how expensive the standard rate of electricity is. The situation gets more complicated for some people when we start to consider EVs, solar panels and time of day tariffs. With an EV on Octopus Agile the average rate per kWh on my last bill was 8.31p per kWh, although that was impacted by the very strong winds and cheap rates at the start of the month. This month I'm guessing I'll end up paying about 16p. Previously I was on Octopus Intelligent where my average worked out at ~15p. 

If you can heat water or weight heat pump usage to cheaper times then the raw price you quoted can be bettered. I also have solar panels which make a small contribution to hot water in winter but means I use no gas for 7 months of the year. I'm contemplating going the A2A route and coming off gas completely.

Would you mind sharing details about your solar panel installation and how much electricity it generates? Looking at the cost of the property from estimates given by the electricity supplier, it is 1.7k per annum, a lot of money for a 3 bedroom house with high insulation (overall EPC C/71)

Netexporter

Do bear in mind that solar PV output is inversely proportional to heat pump energy demand. If I had a heat pump and had to decide between PV or a battery, I'd choose the latter, as you can, with a suitably sized battery, run the heat pump at cheap overnight rates, most of the time. If you can afford both PV and battery, you can get about double for your solar exports than the cost of overnight imports, on some tariff combinations.

matelodave

As said above, you don't get much leccy out of solar panels in the winter when the sun doesn't shine very much and you'd need an awfully big battery to store enough energy to run a heatpump at cheap overnight rates when you need to heat the place.

Not suggesting that a combination of solar and batteries wouldn't help reduce your electricity bill but you really do have to do the sums and decide if you are in it for the long term.

The calculation between capital cost and return on investment depends greatly on the cost of leccy. A couple of years ago when leccy was up at nearly 40p/kwh it looked good, but it could take twice as long to get your money back when leccy is around 20-25p/kwh

Our annual electricity consumption is around 7200kwh an average of 20kwh/day but we use most of it, (around 5,000kwh) in the five months between November and March with the daily average in December, Jan and Feb around 40kwh a day (figures based on 14 years of operation). We don't have the option of gas so everything is electric.

Our worse year we got through 8600kwh and best was 6000kwh (but we were away for most of December and the system was just idling to stop the place freezing)

You'll note that I use kwh rather than cost - cost is a variable based on the whims of the energy companies, consumption in kwh is the only way you can make meaningful comparisons. (a year or so ago our cost was nearly £3k, this year its going to be around £1.7k for the same amount of leccy)

I'm not suggesting that our system is well set up, but it suits us and is some 14 years old, so a more efficient system properly set up could probably beat that. We don't have batteries or solar and we are now probably too old to see a return on any investment on them between now and the old folks home (or wooden box).

As far as I know, a couple of subscribers (@Reed_Richards and @matt_drummer ) on here have solar and batteries and heatpumps and should be able to give you a better steer on the costs, pitfalls and adavatages

matt_drummer

Thanks @matelodave

You can see my heat pump data here

HeatpumpMonitor.org

It's a great place to check out the performance of many systems and I link to it to back up what I will now write.

My system is the Octopus installation in Ipswich.

I have had two heat pumps in the last 12 months, the original one was replaced for a different one on 20 February 2024.

This heat pump, an 8kW Daikin Altherma 3 runs at a SCOP of over 5 since installation.

I have enough solar panels that I generate so much in a year and export so much that my export payments exceed what I pay for imports in the less sunny months, my standing charge and my heat pump servicing.

I pay nothing in actual terms for energy.

The real cost of running my heat pump is about 15p per kWh as that is what I lose in export payments.

I also have enough battery storage to cover the biggest energy use of the worst 24 hours.

That means I pay around 3p per kWh for heating our house and DHW, I'm not sure how that compares to gas prices right now but I am sure it is less.

Right now I use Cosy Octopus but I think I would be better off on Octopus Agile.

I have known this for a while but whilst I have been focussed on getting my heat pump(s) running efficiently I didn't want the distraction of a potentially volatile electricity tariff.

When the colder weather returns I will probably swap to Agile and I think my import costs will fall a bit, I need to look and think about that.

A properly set up heating system using a heat pump can run very efficiently.

Mine is nothing special and I am no genius but my system out performs pretty much everything in terms of efficiency, you don't need Heat Geeks to make a heat pump work well.

What the OP can do and how their system might perform depends on the heat pump and the installation.

I have learnt a lot over the last heating season.

Heat pumps are very different to what we are all used to, the amount of heat produced is not directly related to the energy consumed and it can be a difficult concept to grasp.

Zones, TRV's and turning the heating off are not necessarily the cheapest or most efficient way of running a heat pump even though it seems it would be.

Maybe the OP should give some details of what is installed in the property they are contemplating buying.

matt_drummer

As far as EPC's go, who cares?

Mine was a B89 before the heat pump.

I don't know what it would be now and don't care.

My house is not for sale, but if you purchased my house the annual energy costs are zero.

In fact they are better than that as the annual cost is actually an income.

Whether an EPC assessor thinks our house is an A or a G doesn't change the fact that I don't pay for any energy whatsoever.

matt_drummer

Just to add, our solar panels and batteries are an extravagance that are not necessary, I did it because I wanted to and I could.

We live in a fairly modest 4 bedroom detached house and we heat an all glass conservatory.

Our annual heating and DHW need is about 12,000 kWh. I have used more this year with a difficult heat pump and even the new one was not right until last week. I heat our house to about 22c all of the time.

Even if I had to buy all our electricity at the SVT and our SCOP was only 4 then I would have to buy 3,000kWh of electricity. That would cost about £750 a year.

It's not bad at all.

Any modern heat pump properly installed and operated should be able to get a SCOP around 4.

It depends where you live, of course, further north is likely to be colder but I don't think there is really anything to be scared of with a heat pump.