Indeed!
That should thermosyphon nicely then even if the power does go out during a freezing snap.
2 Likes
@marko do you think this is the thermosyphoning you mentioned?
Looks like it to me. No pump action. Glug of cold wanders through heat meter.
1 Like
Oh! Could thermosyphoning explain the phenomenon I see after heating the cylinder in the summer? The return and flow temperatures gradually drop, and then the return suddenly increases to match the flow temperature. Is it sucking cold water from the radiator circuit until itās all even?
(the internal unit and sensors are on the first floor, while the outside unit is on the ground)
1 Like
Just checking in for an update on my system. A mild day today, but itās the best daily COP I have achieved in the 2.5 years I have had the system, nearly 4. Thanks to the help on here and being able to see the data through OEM. Obviously still at the lower end of the table but itās a 100% improvement on where I was before, and no rapid cycling either. House has been a little warm. The temp went up to 22C this morning, but itās now finally dropped down to 21C. Heating has been off since around 09:30. Itās not your typically low and slow heat pump operation but the house has been warm enough in all but the coolest room at the back of the house.
Heat pump is definitely over-sized, but if it behaves like this it is reasonable. What next to see if I can squeeze any further improvements. Larger rads and a lower temp I guess.
Looks like some more thermosyphoning again today too. 
3 Likes
Revisiting my heat pump.
Itās been working ok, now getting a COP around 3.5-3.7 vs 3 or below before. I donāt think Iāll achieve much better until I downsize the heat pump and alter some pipework.
Every now and then the system doesnāt target dT very well. Today being one of them. Flow rate wonāt drop and remains at ~21l/min. The target delta in the settings is 7C but itās been ticking along at 4C and not dropping the flow to achieve its target. Yesterday it did operate as expected. Anyone have any ideas?
I also have a high standby current from my Altherma 3M Edla09 Monoblock.
Normally it is around 23Watt. Now since a few days around 70 Watt!
Heatpump is off, no hot water production with the heat pump, no heating, no cooling.
I donāt have backup heaters connected to the grid.
Anyone an idea?
Best regards,
Geert
I havenāt managed to track it down yet unfortunately. Itās not significant when the heat pump is running but now we are in the warmer months itās bonkers!
I use kWh/day on Standby when the system is doing absolutely nothing.
Fingers crossed someone comes along with some ideas 
It might be worth looking at those tape heaters on the heat exchanger in/out etc. They are about 33W each, and might be triggered by some wacky alignment of settings and ambient values? You canāt really check without taking the cover off unfortunately, I donāt think thereās any instrumentation. And yes, Iām clutching at straws, but there has to be some reason for the change.
How are you measuring the electricity consumption Sam?
With the Eastron electricity meter. My boost in power draw seems to be random, and not always on like @Geert_Bellens system.
Johnās idea of a wacky alignment of settings and ambient values is my working theory too but i havenāt been able to figure out the combo.
1 Like
Hi Sam,
I donāt know what an Eastron electricity meter is.
So I have to ask, is it reliable and accurate?
I use SM120 meters supplied by OEM.
My standby was always 21W give or take a Watt or two.
What sort of meter is it, temperature stable, stuff like that?
Do you have any other way to verify that the reported consumption is actually correct?
Hi Matt.
Eastron is the brand name of the SD120, I have the 630 (for 3-phase), not that I have 3 phase, itās just what was fitted in the Electrification of Heat trial I was on.
Iām very confident itās correct. It measure all power used by the heat pump. The tricky bit is picking out which particular component is drawing the power. The backup heater is completely off (at the FCU) so it is likely something in the monobloc.
Hi Sam,
Good.
I hope you didnāt mind me asking, itās the first place I would look and I didnāt know what you were using.
I have three SM120s, one on the heat pump, one on the booster and one on the BUH that I no longer have.
I think maybe I have got confused too, I was reading Geertsās post about the standby consumption increasing to 70W and then saw Johnās reply.
Iām not sure now, do you have the same problem as Geert?
70W is a lot, about 1.7kWh per day.
What is the power factor and how does it change when you
Knowing this might give you some pointers towards the type of load. I take it you do mean kW and not kVA or kVAr?
Thatās a good idea - heaters would be closer to 1, being resistive.
The service manual shows the above heaters - it seems unlikely that any of the ON conditions are satisfied, but maybe the W values might be useful clues. Note that the standard setting for the EDLA09-16 is for E11H and E12H to be jumpered ON when the pump is running, so who knows what the side-effects of that might be!
1 Like
Exactly. My assumption would be that adding a heater would move the p.f. closer to unity, adding a pump would leave it the same or worse. I wouldnāt guarantee it would be definitive (which is why I put āmightā in italics), hopefully it will add a clue or two.
Hi @Geert_Bellens, yes I have seen the same issue with my 9kW Daikin increasing the standby power draw from around 24W to 50W. It has been driving me mad, so Iām pleased to see Iām not the only person seeing this! It started in April and has been happening periodically.
I havenāt identified the precise conditions or settings that trigger it. I had thought it might be related to outside temperature, but I canāt prove that. I think it happens when the unit is unused for a period of time and seems to trigger approximately every 24 hours, as if some timer is running in the system.
I have found that changing a setting in the MMI that causes the system to restart usually clears the condition and power draw goes back to 24W. I usually change the tank āecoā set point up or down 1C and that requires a restart.
On a very quiet day, I could hear a slight electrical hum/whine emitted from the outdoor unit and it stopped after the restart.
Are you monitoring your Daikin with ESPAltherma?
I have found the increased power draw corresponds to ESPAltherma reading the inverter frequency as 10Hz. But 10Hz isnāt really a valid value, as 22Hz seems to be the minimum frequency reported when actually operatingā¦
Hereās a day when it happened:
https://emoncms.org/app?readkey=0e9ab50e73d8ae59d9e6dcc70e5dd5f7&mode=power&start=1715385600&end=1715472000#myelectric
We were out of the house at this time (I have Home Assistant send me a notification when it happens), so I tried switching the heating on for a few minutes, as previously I had found that running the system for a few minutes until the compressor kicked in would clear the condition and restore the usual 24W standby power. This is why the flow rate spiked briefly on this day. However it didnāt work.
1 Like
Hi Jonathan,
It stopped after a few days. I really donāt have a clue what is causing this behavior.
I have only space heating, no hot water, neither backup heaters and the heatpump is inactive for the moment.
I dont have a ESP but I do have a good Smappee monitoring in my electrical board, so I can follow in detail strange consumptions.
Starting the heating for a short time can resolve it, but not always.
So still a mystery for meā¦
Geert
Hi Geert,
Did the heat pump go back to 24W at the same time of day as when it went up to ~60W? It looks like it approximately did, from your graph.
My system started drawing increased power at around 12pm every day, but not exactly. It varied from about 11:50am to 12:10pm. Very strange.
Please let me know if you find any correlation with outside temperature, time of day etc.
Thanks
Jonathan