@johnmo my system is already a hybrid with a threshold of 4 degrees. In an attempt to keep things simple the £850 includes an oil cost of £170 so not including the oil part, the ASHP cost was £680
Even above 5 degrees, the ASHP needs to run all day (15 hours on average) to maintain 21C so my good Lady is not cold in the evening. I do not need to run the oil boiler all day, just 6 hours on average to maintain the same comfort level. I would be hard pushed to agree the ASHP will beat anything hands down regarding running costs at the moment sorry.
My oil is now 4.7p per Kwh and my ASHP on average uses 21Kwh at 28.9p / Kwh for an OAT of 7 degree. Even if the ASHP ran at its max efficiency of 500% it could not compete me thinks 🙁
5 Bedroom House in Cambridgeshire, double glazing, 300mm loft insulation and cavity wall insulation
Design temperature 21C @ OAT -2C = 10.2Kw heat loss
Bivalent system containing:
12Kw Samsung High Temperature Quiet (Gen 6) heat pump
26Kw Grant Blue Flame Oil Boiler
All controlled with Honeywell Home smart thermostat
I don't disagree for a minute with some of the sentiments about gas prices vs electricity etc but, to add some balance to the argument:
My heat pump, retrofittd to a 1930s property in SE England with radiators, is working out about 20% cheaper to run than my 15 year old condensing gas boiler.
The secret? I don't really know other than the heat pump is right sized, run on pure WC 24*7, all except 2 radiators without trvs, no controls other than the heat pumps native controller and the aforementioned 2 trvs, and certainly no system separation between heat pump and emitters.
I do get 7hrs of cheap leccy in return for an uplift in daytime rates, so pay on average about 19p/kWh. I don't currently do any 'set forward' to exploit this (actually if anything it's the opposite as I run in noise reduction mode at night which, when it's very cold, reduces the output a bit)
The design ft was 45, actually 42 is the FT needed at the design OAT to maintain an IAT of 21 in the living rooms, a bit less in the bedrooms.
In reality the cost saving is a bit more than stated above because I have assumed for the calculation that all energy used by the heat pump is imported, whereas in reality some comes from my PV.
In addition to the cost benefit the whole house is now heated to a comfortable temperature 24*7. Furthermore I don't have to keep fiddling with controls to keep it that way, temperature swings (with time) and gradients (in space) are much reduced. The house has never been more comfortable!
Was I lucky or did I just heed the advice here, and trust the science when it comes to how to run a heat pump efficiently?
This post was modified 3 weeks ago 2 times by JamesPa
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
@johnmo I appreciate your willingness to help, however I thought I would give you and other readers more detail about the reason for my decisions. I am also conscious of straying too far from the main topic of conversation, therefore I am not looking for help in improving on what is already a finely tuned system, I am merely highlighting the imbalance between electricity and in my case, fossil fuel oil that is starting to, in effect, financial shut people out of the renewables market.
However for your information, here is my situation:
My Wife is a community cancer nurse who, on average, travels 50 miles per day and has an EV vehicle which requires charging 3 - 4 times a week at an average of 35Kwh per charge. This is charged on the Octopus Go tariff which currently charges peak 28.9p / Kwh and 8.5p / Kwh off peak. As my Wife requires the car during the day, it is essential the EV is charged during the night. Due to this being an all year round routine I have decided this would save the most carbon pollution and money.
In addition I have a hybrid Samsung 12Kw ASHP and high efficiency (93.5%) Blue Flame oil boiler, the system, up until recently, was configured to operate the ASHP at OAT 4 degrees and above and the oil boiler below this. The ASHP has been finely tuned using the WC function over 2 Winters and the ASHP very rarely shuts off because the thermostat level has been exceeded (usually due to solar gain at the back of the house). It also has a combined Space Heating and DHW SCOP of 4.25. The maximum Samsung suggest in ideal lab conditions for the machine is 5, so I am more that pleased with 4.25.
Furthermore, the heat loss for my 5 bedroom house for OAT of 7 degrees is about 6.2 Kw / per hour. With a SCOP of 4.25 I would expect the electricity consumption to be in the region of 6.2Kw / 4.25 = 1.45 Kwh and from various observations the pump actually operates in the range 1.1Kwh - 1.6Kwh for an OAT of 7 degrees. From a setup and expected performance point of view, the ASHP is operating as designed and I am happy it is performing to its optimum.
The oil boiler is controlled by a smart thermostat which controls the flow temperature by varying the burn time to maintain the living space at a comfortable level for various OAT temperatures, so at OAT 7 degrees, my boiler uses approximately 650ml of oil an hour (metering grade oil flow meter installed).
Comparing the efficiencies of the ASHP and the oil boiler, you are absolutely correct, the ASHP is way better and I am not going to argue differently. However this comparison is great in isolation and assuming the source energy is of a similar price, but it is not sadly.
To add to the problem, as we all know, having a set back temperature of just a couple of degrees can take an ASHP (especially a tuned WC setup) several hours to recover, so in order for my Wife to be comfortable in the morning and evening the ASHP has to run from 5am to 8pm every day to reach and maintain a indoor temp of 21C for the evening. The system has a setback of 2C for sleeping over night outside that time range. For energy companies to reduce their losses they make during the off peak tariff time, they have to charge slightly higher peak rates. The issue is, I am running the ASHP during the peak time, when the heating is needed. To maintain the same comfort level, the oil boiler only needs to run 5 to 6 hours a day due to its quick recovery time and compared to the EV usage, is only 5 months of the year, so most probably produces less carbon than a petrol engine running the same routine as our EV. Looking back over last Winter, most of the electricity in my area came from the gas turbine station down the road. In this case is the ASHP any greener than running the oil boiler?
I have now modified the system to be operated from a Wifi switch which allows the ASHP to run during the off peak times for generating the DHW and the oil boiler for space heating during the peak times. Over the past several years I have generally consumed about 800 litres a year for space heating at a current cost of 47p litre. I expect my bill to be around £400 for the Winter space heating cost next year.
The one thing I have come to realise on my green journey over the last 3 years is, if you want green tech to be financially viable, your whole supply chain needs to be green. In the case of the home owner, this is generating your own power to a large extent.
Getting back to my point in a previous post, I agree most of this net zero movement is for political reasons and I believe the consumer is paying the price to enable the Government to declare to the climate organisations we are net zero due to all the green generation. However under the hood the system is still reliant of fossil fuels due to the Grids deficiencies, the green generation is not actually used to its full potential but costs us an ever increasing amount to have it switched off frequently.
My conclusion is, without batteries and PV to offset the ASHP running cost for example, people like myself have to decide EV or Heatpump tech. You cannot have both without paying a premium for one of them.
Kind Regards
5 Bedroom House in Cambridgeshire, double glazing, 300mm loft insulation and cavity wall insulation
Design temperature 21C @ OAT -2C = 10.2Kw heat loss
Bivalent system containing:
12Kw Samsung High Temperature Quiet (Gen 6) heat pump
26Kw Grant Blue Flame Oil Boiler
All controlled with Honeywell Home smart thermostat
My conclusion is, without batteries and PV to offset the ASHP running cost for example, people like myself have to decide EV or Heatpump tech. You cannot have both without paying a premium for one of them
That's a curious conclusion with which I am struggling, not least because I have a fairly comparable situation which doesn't seem to create a conflict.
From what you say I guess your conclusion is because of the conflict between nighttime setback and nighttime (extremely cheap) EV charging, which typically comes with a slightly higher daytime rate.
Have you considered that you aren't required to have to have a cheap nighttime rate. Yes your EV will be more expensive to run without one, only about one third the cost of fossil fuel instead of one fifth to one tenth, but that's still an incredibly good deal so I can't quite see that this is a real conflict, you can't reasonably expect the best of everything!
Surely, however, there is a better solution. Presumably you don't sleep in every room in the house. So perhaps you could do what I do, and have the bedrooms permanently a bit colder than the living rooms, dispensing with setback altogether. Alternatively, if you must, put smart trvs in the bedrooms and arrange them to cool at night only. If you combined the latter with a night time set forward, This would reduce your daytime consumption for heating and any very marginal loss of efficiency due to the use of trvs in a subset of rooms would be more than offset by the fact that you are fully exploiting a cheap nighttime rate for your heating in addition to the EV.
Are you sure that you aren't manufacturing a problem and as a result missing an opportunity?
This post was modified 3 weeks ago 3 times by JamesPa
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
My relatively uninformed gut feeling having read lots of articles is that we won't see large falls in average electricity price over time but we need to move to net zero for the environment. It is certainly going to be an interesting journey to watch how it all nets out for the various cohorts of customers, residents and businesses in different parts of the country with different setups. There is lots of debate about what happens to all the current generation under CfD when the CfD expires and we are back to potentially eye watering volatility on short term pricing depending on what is put in place.
Mike - There are strategies whereby both goals could be achieved simultaneously.
One major issue we face is the possibility of having to upgrade the extensive 11Kv distribution grid. Those costs are not included within the £60bn grid upgrade announced last spring by National Grid.
The red lines in the (anonymised) map are 11Kv
There is sufficient capacity on the 11kV supply network, but it's a long way short of being able to allow us all to run heat-pumps and EV chargers. So it needs to be time-sliced.
That, in turn, requires new types of tariff... ... which are currently not available due to the historic regulatory system which sets energy pricing. Grrr 😡
However, the cost of having to upgrade the 11Kv cabling is extremely expensive, and most likely beyond the capability of the country to pay for it. There comes a point where Government has to intervene in a process and say "Stop!"
We've already seen that with HS2, and the 11Kv upgrade is like "HS2 on steroids". 😮
One possibility is to fit 10% of homes with storage batteries. They could be configured to respond dynamically to the 11kV grid which serves that area. Centralised control isn't required.
You would normally expect storage batteries to be installed by the more affluent households.
But suppose we did the opposite...
Why not incentivise Housing Associations to put battery storage in all their rental homes? Those have a high proportion of residents in energy poverty and using pre-payment meters.
It's not generally appreciated that prepayment Smart Meters are just as capable of handling Time of Use (ToU) tariffs as those found in households with credit accounts.
That would allow GB to avoid the need to upgrade (most of) the 11kV grid, whilst simultaneously benefiting the more socially-deprived section of the population.
The challenge is who pays, who holds the debt and the interest rate/cost of capital.
The network operators will source capital for network upgrades, it costs the government no net increase in government capital borrowing which is already painfully out of control. No government will take this debt on government borrowing, especially Labour at this time. That is why getting network upgrades has been the default easy option, it is a hidden cost that doesn't impact customer or the government much in the short term.
Many Housing Associations are also in trouble in the medium term with income looking to fall short of expenditure due to long term high interest rates that were not expected. They would be unable to borrow at sufficient scale to fund the upfront costs of batteries in sufficient homes.
Getting 10% of householders to fit batteries in the right part of the country is tough. The government have already watered down the insulation requirements for heat pump grants and hugely increased the grant to £7.5k else the heat pump rollout was dead...., solar installs after all these years is only circa 5% of domestic properties and not necessarily located in the optimum parts of the country and with many small installs on new homes.
I can't honestly see the government swapping grid upgrades for the option of hoping domestic customers will install batteries in the right parts of the country at sufficient scale. It could be part of a plan.
It will need commercial incentives for companies to install local storage solutions in the right parts of the country for the government to take the risk.
The potential political backlash of any sort of mandatory battery installation in homes may be too much for Milliband? Ditto government grants for homeowners are not easy as this would further increase levies on bills to pay for it.
It is not that the idea isn’t sound technically of batteries in homes, it is the money that is the issue, the upfront capital. This isn't HS2 where the government was funding the capital building. Am sure batteries in homes will play a part but I can't personally see a government relying on mass takeup right now. The upcoming changes to new build homes gives an opportunity to mandate batteries which is being talked about in the press, be interesting to see what happens there.
It will be fascinating to see how it all plays out, including zonal pricing, breaking the electricity price link with gas, network upgrades, financial incentives vs regulations etc. I watch with interest...
No government will take this debt on government borrowing, especially Labour at this time. That is why getting network upgrades has been the default easy option
I believe there's another reason that network upgrades are too easily getting approval from Ofgem.
It seems to me that Ofgem has constrained its role to considering only the alternatives being put forward by the commercial energy sector. At first glance, that seems appropriate. Those are the companies to whom it has issued licences.
However, there are other options which Ofgem never gets to see.
The possibility of subsidising battery storage within
houses owned by registered Housing Associations
homes with pre-payment meters
are invisible to Ofgem because those wouldn't earn profit for a licensed DNO or TNO.
Getting 10% of householders to fit batteries in the right part of the country is tough.
That would depend on the rules for such subsidies.
We already have free insulation retro-fitted to homes, which is paid for out of a portion of the daily standing charge. Ofgem approve that levy because it's easy to appreciate the logic. In most cases the home insulation schemes are run by local authorities... which is how the 'right' parts of the country receive the help.
Storage batteries within the home have a three-fold positive effect on the grid.
those homes would no longer make any demand on the grid during the 'early-evening peak'
they can also be used to reduce losses due to phase imbalance at the local substation (because they would be recharged from a single-phase supply)
and reducing those losses will result in fewer outages because there's much less current flowing in the neutral wire
Reducing losses at the local substation is already written into the DNO's RIIO-ED2 Agreements (to March'28). But it's neigh-on impossible for DNOs to hit that target because they aren't permitted to own or control generation and storage assets.
Fitting an autonomous Smart Charging Controller circumvents the problem.
Those phase-imbalance losses from domestic properties are presently running at 10%. That's a huge amount of energy to be discarding at the last transformer in the chain!
This post was modified 1 week ago 3 times by Transparent
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