Are Heat Pumps Cheaper To Run? Don’t Believe Octopus!
By Paul Homewood
Don’t believe the lies from Octopus Energy:
https://octopus.energy/blog/heat-pump-running-cost/
Let’s see how they have tricked you.
Their electricity consumption for a heat pump is based on an efficiency rating of 333%. In other words, you will get 333 KWh of heat from 100 KWh of electricity.
But this is a wildly optimistic figure, unless you have ultra high levels of insulation and live in the mildest part of the country.
Various studies suggest that an average home would only achieve efficiency of around 260%.
Using Octopus’ prices, with 260% efficiency, we get:
- 14100 KWh of heat = 5423 KWh of electricity
- At 34.19p per KWh, the cost = £1854, compared with a gas boiler cost of £1788
They also claim a saving of £109 from a smart meter, but you would have shift half of your heat demand to night time, which I suspect would be unacceptable to most people and leave homes cold during the day. And nothing comes for free, as the smart tariff charges an extortionate rate of 51.78p between 16.00 and 19.00. So you might save a bit on heating, but you would pay more for all of the other electricity you use during that period:
https://octopus.energy/smart/cosy-octopus/
They also claim a saving from eliminating the gas standing charge, but this would mean you would have to give up your gas cooker, gas fires and any other gas appliances.
And there is no evidence that heat pumps are cheaper to maintain. Our gas boiler is 14 years old, and has literally only needed a few hundred spending on services.
Finally, there is one issue that Octopus have failed to mention – hot water. Heat pumps are not sufficient on their own for supplying the hot water we need everyday.
One solution would be to instal a much more powerful heat pump, but the running costs would be much greater, as well as the capital cost.
There is also the possibility of hybrid heat pumps, which can use electricity/gas/hydrogen to top up the heat of the water. Again capital and running costs increase.
But I suspect most people would simply choose to buy a separate electric water heater, also adding to the installation cost. But more significant would be the higher running costs:
The average energy demand for hot water is about 4000 KWh pa. At a gas price of 10.46p, this would cost £418. But at an electricity price of 34.19p, this rises to £1367.
As far as Octopus is concerned, heat pumps and the Net Zero agenda is a religion. And they will lie and cheat to get their way.
CORRECTION
Please note, I have made a slight amendment to the costings, to reflect gas boiler energy efficiency.
Comments are closed.
NOT A LOT OF PEOPLE KNOW THAT 
Lies, damned lies and anything of a Green
nature
Don’t these things ever break down, don’t you need ‘heat pump cover’?
My guess is that they are less reliable, a modern gas boiler is simple and efficient.
My 2 year old Baxi combi boiler has a 10 year guarantee and I pay £70 for an annual service by the people who installed it. Octopus say their heat pump cover is £159 cheaper than the ‘Which’ average boiler cover. That figure make no sense to me.
There are not global gas shortages either. There’s plenty of gas. Just a few years ago, oil production facilities were flaring it because it was so cheap.
Bigger radiators are recommended with heat pumps. Not cheap.
The interest on the extra capital cost of the heat pump and alterations needed to your home when installing the heat pump are not included, nor is the electricity needed to regularly heat the water in the system to 70°C to prevent the development of Legionella.
I wonder how long the break-even period is when paying back the capital.
They are also noisy beasts as I know from practical experience, especially when running 24 hours a day when temperatures are in the low single figures.
It all reminds me of the claimed savings on smart meters of £41 per year, subsequently reduced to £18, on an installation cost of £500 per unit.
What is the service life of a smart meter?
Who pays? We do through our electricity bills.
I will save a hell of a lot more money by not having one installed at all and I will keep my house nice and warm too with my trusty gas boiler.
Can someone please explain to this ol’ country boy how this works?
‘Their electricity consumption for a heat pump is based on an efficiency rating of 333%. In other words, you will get 333 KWh of heat from 100 KWh of electricity.’
Is it so efficient it sends power back up the line? What kind of magic produces MORE than 100% efficiency?
Nor do I understand:
‘But this is a wildly optimistic figure, unless you have ultra high levels of insulation and live in the mildest part of the country.’
What does insulation have to do with it? Why should a heat (sic) pump get credit for the insulation?
At least £10,000 cost so break even point is never (allowing for current or foreseeable loan interest rates, let alone capital repayment) even before applying the corrections to the made up figure promoted by Octopus (wholly owned subsidiary of SPECTRE perhaps?).
There is no net generation of energy for >100% efficiency, they take heat from the air outside and transfer it inside. The really important figure is how much heat in kW is produced indoors, interesting that this figure is not given. This distraction is how magicians operate.
Gamecock,
exactly, 100% efficiency cannot be acheived otherwise perpetual motion would work.
The significant error is using electricity as the ‘energy’ which of course it is not. The gas burned to produce that 1 Kwh of electricity is far more and that is what should be used in the efficiency calculation.
I have generally used 66% as the losses between generation and transmission to the customer. However using the ground source heat pump Coefficient of Performance of 5 and that no device is 100% efficient that must make the losses closer ot 80%? On that basis the efficiency of air source heat pumps must be far below a gas boiler?
To me it is more efficient to use the fuel at the point of use than use it to generate electricity with all the losses to do the same job?
Efficiency is not the correct terminology.
This should be COP- Coefficient of Performance.
(Output/ Input)
In simple terms for example a COP of 3, will mean you produce 3 times the energy you put in.
COP will also vary depending on the ambient conditions- what is quoted is the theoretical COP and under ideal conditions.
All sounds a bargain doesn’t it?
I would like to see the kWhrs usage for a winter month- including the compressor power usage.
I’m not an advocate of heat pumps , which will have to run 24/7.
Wasn’t “Octopus” the name of the predatory corporation run by the arch Predator Vince McCain (Kevin Kline in dual roles) in the movie Fierce Creatures?
I would like to know exactly what kind/size/insulation etc of house they are using for this calculation. 4,236 kWh annual usage is absolute b****ocks no matter how good their insulation is. Must be a shoebox. As a comparison we have used an ASHP since 2009 and our electricity usage is in the order of 11,000 – 13,00o kWh per annum. OK so our house is maybe not perfectly insulated (definitely not) but it ain’t so bad. Even now if we could have mains gas I would!
You should go LPG or oil ASAP (while you can get the system installed)
Efficiency is the big selling point for heat pumps, but that is nowhere near the full story, more important is the absolute heat output. 1000% efficiency would be useless if the heat output is only 1 kW, which would not even heat a single room, as I recall from my student days living in a house without gas central heating.
Winters have been generally mild for the past few decades, and most of their heat pumps will be in the prosperous (and warm) South, so their averages are highly misleading, especially if they include non-winter months. Any reputable firm would quote the plausible worst case, for the maximum possible TEMPERATURE indoors, not for the annual energy consumption.
Air conditioners…. never cheap to run, need regular cleaning and maintenance and can suffer from brain meltdowns which are expensive to replace. We used to call them wall bangers… these were Piss poor heaters in winter…
Octopus? Guess they think they’re Squid’s in.
(Sorry… 🙂 )
“Most air source heat pumps are between 4 and 15 kW in output which represents how powerful they are. The bigger your home and the higher your demand for hot water, the higher the output should be. ”
https://www.homeheatingguide.co.uk/renewables-advice/air-source-heat-pumps-a-sizing-guide
Hmm, electric immersion heaters, probably sufficient for most households, are typically 3 kW devices (like kettles), so the 4 kW heat pump will leave the air very cold.
I wonder how much a 20 kW heat pump costs, give us that price, not the distraction of average annual power consumption, relative to that of gas.
The only things that have wrong on my oil fired boilers (2) over 50 years are the PUMPS.
To save £700/pa I have to spend £10-20k. So that’s going to take anywhere up to 25 years before I actually start saving money. Bargain.
They’re all at it (and equally delusional):
https://www.msn.com/en-gb/news/world/heating-homes-with-hydrogen-is-senseless/ar-AA1ar1io?cvid=46aabc36684d412e952a7f3084d516e5&ocid=winp2fptaskbarhover&ei=5
‘A recent extensive study by Energy Systems Catapult clearly proved that no property type is fundamentally unsuitable for heat pumps, while hydrogen for domestic heating has been rubbished by dozens of independent studies, as Dr Jan Rosenow’s research shows.’
and
‘“Green” hydrogen can indeed be manufactured with electricity produced from renewables and nuclear, and is truly zero-carbon. But if that electricity is used to heat houses directly with heat pumps, the process is typically four times more energy-efficient than the green hydrogen route.’
I’m sick of hearing about net this that and the other. Its all a load of rubbish. The most effective thing I have done in my old place is install draught strips around the externl door and loft hatches. Cost £15.
Heat pump efficiency is 2.61 at the most, burning methane (natural gas) in your home boiler is the most efficient way of generating heat, the CO2 produced is negligible (not that I believe CO2 is bad). It is about time that this demonising of gas boilers was kicked down the road. Stick with gas.
GeoffB,
no, that is not efficiency that is Coefficient of Performance based on electrical resistance heating being 1. See my other post regarding efficiency.
One massive hole in Octopus’s calcs is that slow-response heat pumps must run for many hours longer than a swift response boiler.
It’s also interesting to note that the BBC’s ECU was recently forced to admit:
https://www.bbc.co.uk/contact/ecu/six-things-the-uk-could-do-to-tackle-climate-change-bbc-news-website
The shysters of Octopus propaganda:
1. “Gas boiler efficiency 83% Average efficiency seen from BEIS gas boiler study”
That study is dated 2009, and was of just 60 boilers.
Click to access In-situ_monitoring_of_condensing_boilers_final_report.pdf
TL:DR
2. Octopus mentions “Energy super-boffin, Jan Rosenow, from the Regulatory Assistance Project reached the same conclusion in his recent analysis.” Rosenow ought to know better. He mentions Coefficient of Performance (COP).
The Seasonal Performance Factor (SPF) of a heat pump is the ratio of annual heat generated to the annual electricity consumed for the operation of the heat pump. it is the SPF that tells how efficient a heat pump is on average. i.e. the crucial factor.
3. Octopus’s HP is so new it’s highly unlikely to have even had 60 units in field trial for one or two years to provide relevant data.
This 2021 study “Heat pumps and UK’s decarbonisation: lessons from an Ofgem dataset of more than 2,000 domestic installations.” is what should be the comparison.
See page 27, “Table 15: Results for Sample 2 Tukey (ASHP installations only): Total in Sample 219 Average Actual Efficiency SPF 2.72”
So SPF of 272% from in-use heat pumps vs Octopus’s ‘brand new’ un-field trialled model claiming a COP of 333%.
Click to access performance-data-research-focused.pdf
Octopus tries to compare apples with oranges.
“That study is dated 2009, and was of just 60 boilers.” Actually Joe it wasn’t even that many.
“due to occupant changes, occupant requests for removal from trial, and failure of monitoring or recording equipment, not all sites recorded 12 months of consecutive acceptable data. The main conclusions are based on the results from 43 boilers for which a full 12 month data set has been obtained.”
Notice that “failure of monitoring equipment….” Maybe they eliminated results that didn’t suit the desired figures they wanted.
Thanks Ray – Thankfully I included the caveat ‘TL:DR’! 😉
Likely the same statistics wizards who proved that experimental, “Emergency Authorised” Gene Therapy jabs were “safe and effective.”
Sorry Joe in reading that report again it is so clearly flawed (probably deliberately) as to make it completely unacceptable. For gas boilers they add in allowances for heat losses from pipes and tanks which they exclude from heat pumps under the false claim that in the latter’s case they contribute to the space heating. The report is a blatant fix.
FFS are companies like Octopus in control of the entire universe? Who lets them come out with total bollocks like this with complete impunity?
Firstly the co-efficient of performance of any heat pump is dependent on the differential between the hot side and cold side temperatures i.e BASIC PHYSICS!!!!! It is never, not ever, a preset figure.
The oft quoted 3 to 1 CoP for an ASHP is based on a cold side temperature of 7°C and a hot side 0f 35 °C. If the cold side is colder, the hot side hotter or both then the CoP drops dramatically. When the mercury shows freezing the CoP falls off a cliff and at much lower is on a par with a direct resistance heater of 1 to 1.
7°C is not particularly cold is it? It is colder than that most of the winter in Newcastle every year. https://en.wikipedia.org/wiki/Newcastle_upon_Tyne#Climate
35 °C is NOT hot enough for safely stored hot water which requires at least 60°C to avoid dangerous bacterial build up.
35 °C radiators will NOT heat most houses quickly enough so will require almost continuous operation of the heat pump AND the circulating pump pushing the lukewarm water around. A pump (on enlarged radiators and larger diameter pipes hence larger water volume) requires in the region of 150W. Run that pump that at least 16+ hours per day at peak rates (as opposed to 6 hours daily for a normal gas boiler operating cycle) will on its own rack up a much larger electricity bill.
Then stop and calculate how much extra electricity required from a peak rate immersion heater to raise 120litres of water (typical hot water storage tank) from 35 °C to a safe 60°C (a ΔT of 25°C ) with a specific heat of 4,184J/kg/°C each and every day to avoid Legionella. It comes to over 3.5kWh rate for just one tankful.
The circulating pump and resistance extra water heating alone will run out at the very least over £2.50 per day (£75+ per month) – each and every day of the winter. Probably a lot more and of course all on top of the heat pump operating costs.
The BS around heat pumps is pure propaganda – anyone with basic science understanding knows that…unless they are employees of Octopus or just plain dumb.
Don’t forget the Octopus employees are probably on bonuses for every heat pump they can sell. Amazing what people will do for a bit of extra dosh!
+1 👍
Paul, any chance that you refer Octopus to the ASA
Good idea!
Yes, I’ve just written to the ASA to complain that Dogger Bank’s claim that their 3.6 GW of installed capacity “will be capable of powering up to 6 million homes”. Firstly because of intermittency and secondly because even the average power does not cover Ofgem’s figure of 2900 KWhrs/year for the average home
German manufacturer Viessmann is selling its heat pump business to American company Carrier Global which is a surprise given that the German morons intend to ban installation of gas and oil boilers next year. Their numpties also want to ban wood and pellet heaters in new buildings.
‘you will get 333 KWh of heat’
Is this an English thing? Or obfuscation? On this side of the pond, we rate heating in BTUs.
People would look at you funny if you talked about KWh’s of heat.
No GC it is just a science thing. Nothing wrong with measuring heat energy in kWh and it is the worldwide norm these days you know. It’s just Americans who insist on using weird antiquated units like British Thermal Units – we Brits gave up on those years ago.
This might help! https://www.rapidtables.com/convert/energy/kWh_to_BTU.html
We’ll see who lasts longer, Ray.
Sorry, complete garbage. We are all electric in a predominantly 1830s house. The current electricity bill including our ASHP is £110 per month.
Rubbish!
An average house with gas heating and cooker uses about 5000 KWh of electricity a year. At current rates that alone comes to £140 per month!
Do you only use candles in your house?