Calculating your system equilibrium temperature (as a first step to setting it up);
Here is a quick calc as to what flow temps produce what output - if your radiator system produces 9kw at 50/45/20 - assuming all TRVs are set at max. and the system is balanced.
Flow
Rtn
Output
kW
50
45
100%
9
45
40
76%
6.8
40
35
53%
4.8
35
30
33%
3.0
30
25
16%
1.5
25
20
3%
0.3
This suggests you need, at least, a flow temp of 40c and a DT of 5c to fully use the minimum output of a heatpump that has a minimum compressor power of 920w (at 10c) with a COP of 5.
(5 x .92= 4.6kw)
If you set a lower flow temp you will waste some of the output and get a lower COP.
Thanks for the additional posts on the âthank youâ thread.
I have now got reheat working without the immersion kicking in (I think), just waiting for this evenings bath/shower usage by the teenagers does what I expect.
The fixed flow seems to really be working. A long runtime this morning, then itâs been off all day, itâs getting a little cool now, down to 20C by the controller, so it wonât be long before heating comes back on. We have it set to maintain 20.5C
Iâm not sure I have all the settings correct but Iâm going to run through the other post and write them all down in one place.
COP today is much improved, up from about 3 to about 3.6. The long standby is now dragging it down coz it uses some much on standby.
Your system fits the Carnot Heat simulation very well (heatpump factor 0.5), except when short cycling which is probably as expected. This shows that it is possible to get good performance from these units if they are configured correctly. Itâs curious why some other systems canât manage this well, particularly at the start of a good long cycle.
@HydroSam You can use the âExport MMI settingsâ option on the Installer mode Installer settings to put all your settings on a USB stick - db-export.ini - which is just a text file you can read, or even compare to other sets of settings. Itâs a good way to track/record what you had/have at any point - I get confused easily!
Given that youâre presumably running hotter for longer periods, with off periods to get the required average heat output, how much does the perceived room temp fluctuate? The continuous rather than on/off behaviour of a heat pump is one of its attractions for me, I hate the âboiling then freezingâ syndrome.
Iâm not running much hotter, maybe 4C hotter than it was. Itâs brought the house up to temp and then been a very gradual drop in inside air temperature, but my house is well insulated (hence pump being over-sized).
Todays example, 20.5C target at 05:00, it reaches this about 07:00, raising from 19.5C over night. It went off about 09:30 ish having reached 21.5C and itâs only now back down to 20C and turning back on. Now itâs not been too cold today, around 9-10C. Iâm sure the colder days will bring longer run times but indoor temperatures arenât bouncing like they used to with a boiler.
What is annoying is that the pump is continuously running, itâs the Daikin anti pipe freeze solution, why itâs set as high as kicking in at 9-10c is anyoneâs guess. If anyone knows how to drop this to something more sensible like 3C please let me know. The pump has been drawing ~100w all day for no reason!
Iâm guessing @ColinS might know the secret code as his system isnât running the pump during quiet times today. Unless you have glycol in your system?
Hi Matt.
Continuous and sample are a different thing, looking at the leaving water temperature. I am looking at the frost protection settings that run the circulation pump to stop the outdoor pipework and unit freezing if itâs not in operation.
My heat pump wasnât needed through lots of the day today but because the ambient outside temp was around 9C, the heat pump has been circulating water to stop things freezing up. A little unnecessary at that ambient temp, so Iâd prefer to stop this threshold a bit.
Google suggests itâs setting 4-04. The installer manual I have doesnât list all the settings unfortunately.
I have the older Daikin Altherma r410a monobloc model. I think most codes are the same but this one is slightly different. I have managed to find a manual through that site for an EDLQ07CAV3, I have the EDLQ11 but canât find that one. The manual is really poor resolution but I think it says that continuous and intermittent are the other way around, 0=continuous. I donât want to turn it off really do I? I just wanted to turn down the temperature it kicked in but I can find this anywhere. Maybe itâs not configurable on my model.
If the system is in a state that would be able to turn on the pump in order to avoid freezing pipes, at that same temperature, 99.99% chance the system is in the state where it runs in heating mode 24/7
If it were installed eurostyle (high enough off the ground to be clear of leaves and snow) then it would also thermosyhpon hotter water from the house into the outdoor unit and flush the cold back into the house when the pump isnât running and the outdoor unit is at leas than 20C.
This is interesting, and I assume because youâre runninng room influence (Modoka) rather than Leaving Water control (pure weather compensation)?
Madoka sends a signal when no heating demand to turn off the pump (that seems to use excessive elecctricity (~150w) when just circulating and no compressor runningâŚif Madoka not used, this signal canât be sent.
I run Leaving Water (weather comp) as the hysteris control using Modoka drove me mad I and couldnât get on with it, so switched November '22.
One consequence seems to be this symptom of the pump running constantly, so I use Home Assistant to âturn offâ space heatingâŚwhich in turn turns off the pumpâŚit then kicks back in periodically (~3-5mins) only when outside temp is at or below @5C (which is still annoying).
This has caused me to (test) re-instating the old honeywell controls that were removed by Octopus for the actuators on the 5 UFH loop, as the piump just takes the heat stored in the 80mm screed, and just runs it outside! Dâoh!
One useful side effect is I can load shift again now with the UFH, heating is only overnight on the 6hrs Intelligent Octopus off-peak rateâŚthis seems to work really well actually.
Yes, I am using the Madoka to keep the room temperature in check.
My heat pump puts out too much heat for the house so itâs either really short cycles and rubbish COP at lower flow temperatures or run it longer but hotter.
We end the day at about 25c indoors. Itâs not great.
I can probably change it but it has been a month of experimenting to find something that works.
I think we have exhausted most if not all of the possible ways of running it so it is either live with what I have and find a compromise, get a smaller heat pump or double the radiator size and find a better compromise.
I have joked with a few people about installing a radiator outside, or maybe in the garage would be better.
It sounds a bit mad but maybe not, I have a spare large radiator that I could easily install in the garage.
I know my radiators heat the house quite happily at 35c flow or lower, maybe dumping some of the heat produced outside the house when itâs not that cold would end up with a better overall result.
