I am looking at my heatpump and I can see it keeps ramping up and down. While it is not cycling and the COP is pretty good I feel if I could get this under control it would be even better.
Currently set to room stat (Madoka not external) and 40@-3 - 30@15 as it seems to run better in this range without cycling. I could set this down to 25@15 but it causes some minor cycling.
I have set it to fancoil and tried with the DT set to 5 and now 3 but it still seems to be running at 7l/m and will not just maintain the 285w at minimum usage.
I am currently waiting on four radiator swaps so this may make things better and it could just be due to the system being up to temperature / overheating in some rooms but any ideas are greatly appreciated.
I’m finding your swap an interesting one Zak. As I might have mentioned I have the 11kw Altherma, at it’s massively oversized. I’m just down the road from you in Farnham, so we get very similar weather conditions. You COP is much improved, and much better than mine but electricity usage isn’t much different. The big benefit is likely a more even heating strategy in the house.
For your system, a slightly crazy thought, are you shedding too much heat through your radiators and that’s why it can’t run at the target lower dt? If you drop the LWT slightly doesn’t it maintain a more steady pattern or go straight to cycling as you mentioned? Or is it the imbalance of radiator output causing the issue, so once you’ve replaced the remaining four it’ll be better? I think I’ve basically come back with the same argument you were putting forward
I have found the electric usage is about 6-8 kw less a day for the whole house and the only change has been the heatpump. It also means we can now run mainly off of our battery and solar / cheap rate electric.
I have seen and read some of the oversizing horror stories sorry to hear you got caught up in it too.
It is nice to be in a position where you don’t have to wear a t-shirt and shorts indoors, True first world issues I know.
I have been chatting with Matt who still has the volcano 9kW unit. I have tried raising and lowering the DT (set it to Radiators and then fancoil with a DT of 3) but this did not help (other than for that initial hour or so.
What is confusing me is that the return is going back 100% stable, so the heat is going out of the system but the pump is not liking something that is going on.
Happy to meet up for a at some point and discuss if you want as there are some nice watering holes around the Surrey/Hampshire borders.
I can’t remember how far we got and what we changed. I am not sure my last plan was implemented fully but I could be wrong.
This is what I intend to do based on my experience with the 9kW as that is all I have.
I think the flow temperature isn’t stable because of the wdc and the Madoka influence.
So if you haven’t just go straight wdc, no overshoot, no Madoka and no wdc.
It should sit at whatever flow temperature you set.
I run as radiators as it just allows the dT to widen as much as it can with whatever flow temperature I set. It is always running at the lowest flow rate like this which is 10lpm for me and 7lpm for you. Like this the dT set by fancoils has no influence on the flow rate or flow temperature, the heat pump should maintain the flow temperature and the house and radiators will set the dT as you will never get to 8c.
Like this you should be able to find out what flow temperature you can get at the lowest electrical input.
You will also see what the maximum dT you can get is at this lowest flow temperature. It will vary depending on the outside temperature and the internal temperature, basically varying depending on the heat loss.
So, I apologise if we already went this far but I am not sure you removed all other influences in the test we did?
Once you know how much electricity different flow temperatures use and the dT possible you can then use this information to set up the wdc, and Madoka with modulation and overshoot as necessary, but with the basic information you will be able to see what positive or negative effect those additional influences have. You will know how it was without them and if it is better or worse.
This is what I am going to do, our houses are different of course, but the principle is the same.
Hi @KnightPhoenix Zac,
I have the same power fluctuations with our 8kW unit, I think it’s normal and not an issue?
Overnight steady state COP was 4.8 mean, outside temp of 6.5 mean, just the downstairs radiators were open as our upstairs zone set to 18 upstairs was closed. At 7.5p a kW its way cheaper than Gas, the HP stopped since 9am and the house has only dropped 1 degree 7 hrs later, we also have full batteries in the cars and powerwall .
Madoka controls set to 20 (24/7), modulation 8, fancoil, DT 5
38 at -3 and
32 at 15
sure @KnightPhoenix, no probs, see below, hope it helps?
Our Design temp is 45 at -3.3 but, I have moved way off this point on the WDC and the house is still really nice and warm, with long heat cycles.
Downstairs has no doors closed and could be described as open plan…
Note - most of the time the bedrooms are closed via TADO TRV’s with a set zone temp of 18 (one wall stat controls all TRV’s), all other rads are usually open. Controlling the upstairs temps means i do not have to use a setback methodology and can keep a consistent 21 temp downstairs (set to 20 on the madoka), 24/7 and it works
BTW I have turned down all the brightness on the madoka, LED and backlight etc with an offset of -0.5 to give a really accurate measurement, I have other sensors that confirm this is good!
We compared it to British Gas’s survey (bedroom description wrong) and had a similar design just £5k less with Octopus. BG were going to fit a Vaillant 7kW with no re-pipe, Octo 8kW Daikin but with a ‘full’ re-pipe. BG were awful, quote and contract signed in Nov 2022, install would have been 9 months later with no communication, countless lies and excuses and hassle to even get an install date, Octo turned around a quote in 2 days, signed and installed a few weeks after, we are so happy with our system in our 200 year old house that has never been so comfortable and warm in 20 years.
I have the EDLA06E2V3 installed by Octopus (in March last year) and I’ve now found I was lucky for them to have installed emonHP alongside the heat pump and even more lucky that I wasn’t sized the 9kW version of the Daikin from all the horror stories on here.
I recently found your stats on heatpumpmonitor @KnightPhoenix and noticed you were getting much better SCOP, so I’ve since been tuning my settings and getting much closer performance to your HP. I’ve seen very similar ‘steps’ in flow temp, especially once they get close to the minimum temp that the heat pump seems to be able to run for extended periods, for my system that seems to be 30C.
This was when I was using the Madoka for control but I was steadily reducing my modulation value anyway as all I really notice it doing is driving SCOP down/contributing to cycling, so inspired by this thread I’ve moved over to LWT control and going to see how it performs. My dashboard isn’t public yet but I’ll report back on findings.
My WDC is 45 @ -5 > 30 @ 10 and that has been keeping the house at a steady temperature and moving towards SCOPs of 4+ even over the last couple of weeks of temps below 0 and up to now with temps at the range I’d describe as Daikin Altherma’s ‘difficult zone’ at 10C+
Thanks for the update, Not fully sure of the impact of the modulation but I am not a fan of the on / off cycling and repeated restarts I am seeing so I have turned it back on for now (at least until I have the new radiators in place).
You may find it beneficial (if you are open to some change) to use HeatPunk and try designing your house for a 40 or 35°c flow rate and seeing the radiator changes required. The only reason I did not get to 35°c was due to an oversized dining table and lack of room for the additional radiator.
Hopefully you can share some screenshots or stats once you have finished modifying.
Thanks for this, it is interesting to see that your system is also unbalanced and is probably also part of the reason you have to zone and close the circuits off (not ideal for running a heat pump).
Ideally your coverage for all rooms should be between 100 - 107% as with that you could balance out any difference on the lockshield valves. Then due to the extra water volume and lower flow temperature the system would likely have a higher COP.
Personally I would look to run the system through HeatPunk and try to get all radiators as close to possible to the required temperature (40 or possibility 38), This will not only allow you to lower the flow temp, increasing COP but will also reduce the number of defrost cycles in cold weather.
This all depends on how keen you are to tinker with the system and how much you want to take part in the race to be Top of the SCOPS
yes, the bedroom rads were existing oversized and not replaced (excepts the K3), TBH it’s all good and I think our system is ‘good enough’ at a flow temp of 29 ish, or COP is usually over 4 in Jan, over 5 today at 9 degrees outside, no such thing as perfection
PS the good wife is happy and warm, so life is good!
Just as a follow-up to my post above, my experience with LWT control was not great. I saw a lot of cycling at external termperatures and target LWTs that with room control were not happening (I really don’t understand why that would be the case, though some of the things the Daikin unit does from one-day to the next can be difficult to understand!).
So I’ve gone back to these settings:
Madoka room thermostat control
WDC 44@-10 > 32@10
With these I’m getting some pretty decent runtimes and SCOPs between 4.3-4.5 now (heating and DHW combined), which I think might be the best I can squeeze out of the 6kW unit at my property (without doing rad changes)…I’m pretty happy with that. The house is really comfortable and electricity use is under control.
One setting that I can’t edit on my system, which I think would help reduce cycling is overshoot. In the installer manual I see that I should be able to set this between 1-4C. Mine is set to 1C and I cannot modify this at all. This is using the installer user profile and when set to either LWT or room thermostat control.
Are you able to freely change this setting, like all the other settings within the MMI?
The bar chart is reading the kWh feeds that are accumulated directly from the inputs, whereas the power chart is added up from the watt feeds. The power feeds are quite noisy, and are sampled at a higher interval (60s) for the purposes of charting. This will mean some values will be skipped, hence the discrepencies.
Yeah the ability to split out the DHW from space heating was my main driver for getting the ESPAltherma, had it a few days now and as well as splitting the usage, it’s also great to have immediate and accurate to 0.1C readings of the target LWT. That is really useful to understand what the unit is actually up to, you can see my dashboard here: Emoncms - app view
I only have the bottom end so low for the easier mental arithmatic of what the LWT should be at a given termperature . Essentially this is targeting 39C @ 0C…and my family won’t be unhappy with the extra warmth on the very few occasions the temperature actually ever gets significantly below 0C here in the south of England.