Many of us on here are interested in the COP of our heat pumps to see how efficiently they're running but most people will only be interested in what happens to their electricity consumption and bills. You often see claims that heat pumps will reduce your energy costs but is that correct?
So, how has your energy use changed? What about your bills?
Back to "normal" electricity use yesterday. Still over 30kWh but that seems to be standard in cooler weather. It is a bit frustrating being unable to take advantage of a two rate tariff or a TOU tariff to bring the bills down, particularly as our system, with heat batteries, is perfect for it. But I'm using the trial period to learn how the system performs so when it ends I'll be better informed and able to choose the best tariff.
Also do you have a split between kWh for the heat pump and that for the sunamp?
We have two batteries that feed into the central heating and these are heated by the heat pump. The timing for when these are charged is currently controlled remotely, by the Kaluza platform.
We then have a battery heated by the heat pump for hot water (controlled by Kaluza) and a second battery, also for hot water, heated by an electric heater. Our water goes through the first battery where it's heated to 43 degrees then through the second battery where it gets to 65 degrees.
I can see how much electricity the heat pump is using and how much the entire system is using (pumps, heater, valves etc) but it doesn't break down into any more detail.
What’s the thinking behind the concept of taking the DHW as high as 65degC
It’s now common practice to fit thermal mixer valves in houses in order to prevent children and elderly people being scalded. the common default setting for these is 42degC.
So by that logic the additional rise from 43-65deg in your house is superfluous…. and goes against safety guidelines.
We have a mixer valve so we don't get 65 degree water at the taps. We get hot water at ideal shaving temperature 
The second heat battery heats to 65 degrees by default. There's no way to turn it down. I assume it's been installed to keep us in hot water if the heat pump isn't working (like an immersion heater in a normal hot water cylinder).
I have wondered what temperature water we would get if I let it run down and didn't bother recharging it.
What’s the thinking behind the concept of taking the DHW as high as 65degC
It’s now common practice to fit thermal mixer valves in houses in order to prevent children and elderly people being scalded. the common default setting for these is 42degC.
So by that logic the additional rise from 43-65deg in your house is superfluous…. and goes against safety guidelines.
What’s the thinking behind the concept of taking the DHW as high as 65degC
It’s now common practice to fit thermal mixer valves in houses in order to prevent children and elderly people being scalded. the common default setting for these is 42degC.
So by that logic the additional rise from 43-65deg in your house is superfluous…. and goes against safety guidelines.
My understanding when i looked into them some time ago, of course i may be mistaken....
The charge and discharge temperatures are different. The devices aren't flowing out water at 65%, it flows out around 40 degrees i seem to remember. Although there are quite a few different models so it may well depend on the setup
There was some info in the manuals on temperatures but i admit i only skim read.
I checked with Sunamp, as the first battery is unusual in having such a low temperature. They confirmed the output temperatures.
Had a scary £7.50 electricity day on Sunday (according to my smart meter - still transitioning to a new supplier so I don't have online access yet). However, that seems to be down to the pump running unnecessarily long when the temperature is at its coldest.
I have my thermostat set to 20.5° from 6am to 10:30pm and 18° overnight. What I have been finding is that the heating comes on at 19° and keeps going until it gets to 22° (so a tolerance of 1.5° each side.
With some of the cold outside temps we’ve had recently, it seemed like the pump was struggling to get up to the desired radiator leaving water temperature (LWT) of 50°. I would check around 9am and the LWT would still only be 41° after 3 hours of operation. It would then limp along until midday with the rads warm at best. When added to a second round of heating later in the day, and reheating the hot water after a bath, the result was the £7.50 day 
What I did on Mon and Tue instead (still cold outside), was stop the heating around 8am when it had got up to 20-20.5°. This meant that the second round of heating happened earlier in the day - mid afternoon - and with higher daytime temps it raised the house up to 22° pretty quickly. This has resulted in 2 consecutive days with pretty similar use both at less than £5 rather than £7.50.
I’m wondering if the system scales back the LWT after the target temp has been reached, and then operates at lower temps to do the tolerance above the target (i.e. between 20.5° and 22° in my case)? If so, doing that seems to have caused my system to run for an unnecessarily long time and increased rather than decreased costs.
I’m noting those comments
If that strategy reduces the overall electricity consumption for you, then it’s something we need to be fed back to Kaluza.
If they built in support for that within the Flex Platform and Time Of Use tariff, it would be very attractive to the growing number of consumers with Heat pumps.
The part that needs careful thought is how Flex might be able to ‘stop the heating around 8am’ without manual intervention. There needs to be remote-operated switch installed somewhere.
Flex incorporates weather-input and AI machine-learning algorithms. So it has the potential to do the calculations as to when it’s optimal to turn off and then restart your system.
Hi
That would certainly be attractive. In the meantime, as a workaround I’m thinking I could extend my daily schedule to three temp changes rather than two. So I might set it to 20° between 6am and 8am, then 20.5° between 8am and 10;30pm and then down to 18° overnight.
If I change the thermostat manually when it’s running then that normally stops the pump, so hopefully a schedule change will do the same. For example, if it’s running and the temp is currently 20.5.°, it doesn't matter if I move it up to 21° or down to 20° in both cases, it stops running (presumably until the temp fall to >1.5° below target).
Let us know if that temp-change idea at 8am does the trick.
If not, then I have a number of other ideas how to go about it. It’s obviously important to ensure that the mechanism
Are you aware that we have a video-chat with Robin Abraham of Kaluza next Tuesday (7th)? Have a look at the Invitation and the questions/points already suggested.
Had a scary £7.50 electricity day on Sunday (according to my smart meter - still transitioning to a new supplier so I don't have online access yet). However, that seems to be down to the pump running unnecessarily long when the temperature is at its coldest.
I have my thermostat set to 20.5° from 6am to 10:30pm and 18° overnight. What I have been finding is that the heating comes on at 19° and keeps going until it gets to 22° (so a tolerance of 1.5° each side.
With some of the cold outside temps we’ve had recently, it seemed like the pump was struggling to get up to the desired radiator leaving water temperature (LWT) of 50°. I would check around 9am and the LWT would still only be 41° after 3 hours of operation. It would then limp along until midday with the rads warm at best. When added to a second round of heating later in the day, and reheating the hot water after a bath, the result was the £7.50 day
What I did on Mon and Tue instead (still cold outside), was stop the heating around 8am when it had got up to 20-20.5°. This meant that the second round of heating happened earlier in the day - mid afternoon - and with higher daytime temps it raised the house up to 22° pretty quickly. This has resulted in 2 consecutive days with pretty similar use both at less than £5 rather than £7.50.
I’m wondering if the system scales back the LWT after the target temp has been reached, and then operates at lower temps to do the tolerance above the target (i.e. between 20.5° and 22° in my case)? If so, doing that seems to have caused my system to run for an unnecessarily long time and increased rather than decreased costs.
Really good to see all this learning.
Could you explain what a leaving water temperature of 50 degrees means and why it is important in your setup?
Do you know if your heat pump is setup with any sort of weather compensation, ie lower flow temperature at higher outside temperature and higher flow temperature at lower outside temperature? Or is the heat pump setup for a fixed flow temperature for the heating irrespective of outside temperature?
With some of the cold outside temps we’ve had recently, it seemed like the pump was struggling to get up to the desired radiator leaving water temperature (LWT) of 50°. I would check around 9am and the LWT would still only be 41° after 3 hours of operation. It would then limp along until midday with the rads warm at best.
Sure, signature updated 
50° LWT is what the Daikin engineer who did an audit set it to (the installers had it at 55°!). As I’m quite happy with the heat levels in the house, I might try dropping it a degree or two.
42° does seem quite low for radiators though. When mine were not getting above 41° they were warm at best and it took forever to heat the house.
Ah ha! Maybe mine’s too low !!
My husband and I built an energy efficient home a few years ago with air source heat pump, underfloor heating and excellent insulation. Our rural site has no gas and so we rely solely on electricity. Until last year we have had fairly low electricity bills. I, as with the rest of the population, was fully expecting my bills to increase, however not quite at the rate they have.
I would like my account to be investigated as my bill from 5th March 2022 – 29th May 2022 showed a total electricity charge of £1682.54!!!!!!! The charge for Dec-Mar was only £371, and that was the middle of winter. How is this possible?
An engineer recently came out to fit a Smart Meter and was astounded when I told him this.
Because of this charge we are now in debt and our monthly charges have gone from £200 per month to £461 per month. Although I understand on paper it looks as though we have used £1682.54 this can surely not be correct and I don’t see why I should have to pay this until it is investigated.
On checking my Direct Debit on ‘My Ovo’ this new amount of £461 has now been set and I am NOT able to change it to a lower amount. It infuriates me how energy companies and ‘set’ direct debit amounts IN ADVANCE. Myself and the rest of the population are not daft. OUR money sits in your account making YOU interest. I would love to see that figure!
Please advise how this can be sorted as myself and my husband are becoming increasingly stressed about the increasing cost of a debt we don’t believe is ours.
The old meter will have been sent for calibration checks. So if it was in error you’ll get to know.
On the other hand, if the floor heating was left on so the heat pump didn’t have to do so much work then you’ll have used way more electricity. I’m assuming that the readings on this bill were correct - no transposed digits or the like. If the readings are correct and the meter isn’t out of calibration, then I think you owe the money. Sorry.
Does your heat pump give you records of electricity use per month ? It would be useful to get that data to compare each months meter readings. I would imagine that would eliminate the heat pump as the culprit.
Hey
Sorry for the issues you’ve had.
On the large bill or bills, are there estimated reads? When your old meter was removed the engineer would have taken a photo of the final reading- this reading will also appear on the yellow or white sticker on your smart meter.
I’d check the readings are all correct. If your bills were estimated for a long time and then we took an actual read this could have caused a large ‘catch up’ bill.
You can send screenshots of the statements for us to have a closer look, but please remove any personal details first.
Let’s get to the bottom of this!
I had a Mitsubishi Ecodan 8.5kwh pump and system fitted last week after living in the house with storage heaters for 10 years. 60kwh a day in winter is not unusual with storage heaters especially where I live, in the Highlands. So if this new system uses up to 60kwh in winter I will not be phased by it, but based on just one week’s usage I am blown away by how cheap it is compared to what I had before. The day before the installers came, with my five storage heaters, I used 40mwh off peak (I am on an Economy 10 tariff and the storage heaters used most of that 40kwh) and 3kwh Peak. The day after the installers left, with the new ASHP
I used 7 kwh Off Peak and 8 kwh Peak. Of course, it is only May, and it is mild. I have the temperature set at 18.5, the water is 50, it’s on all the time, at the moment I am having the temperature at this level because I need to know how this thing is working and how much it is using, but there is a wrap around warmth in the house even though the radiators never get above tepid, and there is hot water whenever I want it. I have tried 19 degrees and it is sweltering hot….
If in winter this system uses 3 or 4 times as much electrcity as now, I will still be quids in, and I might actually be warm for a change. The general drift online is that leaving this system on 24/7 at a fairly constant settting, moving the temperature up or down only by .5 or so, is the best way to go. It seems to me that folks who had gas central heating previously, have some difficulty adapting to this, and they expect the radiators to be blazing hot to the touch, and the heating to be on a timer .
It all depends on what kind of system you had before. Here we do not have access to gas, I was losing sleep over the approaching end of my fixed tariff in September, and I am used to a ‘system’ where you have to have the heaters on all the time, but I am also used to them never adequately heating the house even with 60kwh a day usage. The Council and homeenergyscotland paid for this system, so it is a Godsend as far as I can see, HOWEVER as Ovo/SSE do not currently offer ANY incentive tariffs for heat pumps unless you happen to be in a few small areas, I shall be moving over to Octopus in September even though it will mean getting a smart meter, which I do not really want since there are so many bad reports about them not actually working.
Incidentally, I was left with practically zero information as to how this new system works or the settings, I wasn’t even asked whether I had a suitable router etc, and I certainly wasn’t shown how to change the settings, or how to set up the melCloud app or even that there is a wifi adapter or what it looks like - and it seems to me that many people, like me, have to do the research for themselves on the internet. Fortunately there is a lot of stuff available especially on youtube.
That’s really good news
It’s a bit insulting to be told not to touch the controls isn’t it! I wonder if it’s a misogynist’s thing ?
I've also got an Ecodan heat pump and have played around with the settings quite a lot. If you want to chat about what you can, and can't, change let me know. I haven't broken anything yet 
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