Hi everyone. This community has been very useful for me since late last year. So, firstly, thank you all very much for sharing such detailed information, its been incredibly helpful. Did the 9kw to 8kw swap in February having experienced much the same issues as many others resulting from incorrect heatloss survey results. Anyway, aside from the new heatpump still being oversized and the heatloss calculation still being wrong, it is working to heat my house at a much reduced cost.
Something odd has started happening since the daytime temperatures went up though. On the sunniest days we’ve had so far, the pump hasn’t completed the scheduled DHW run, in fact, it hasn’t even started it. I’ve tried to get it to run by; setting a new sheduled start time, setting it to reheat only (tank temp was 29 degrees, eco set point is 44), using powerful mode (immersion heater works, pump does nothing), setting it up so that CH is required but nothing can get the pump to run. On days when the temperature outside is lower, the DHW schedule and reheat works just fine. The pump is againt a south facing wall at the back of the house in full sun. The external temperature sensor on the pump has reported 40 degrees+ at points. The external sensor on the north side of reports 20 degrees at the same time. Sometimes the pump temperature sensor reading is greyed out on the MMI display, sometimes not. Looking at the data from the OEM system, the switch to DHW is attempted at the scheduled time but it immediately stops. The ESBE doesn’t move. Octopus engineers visited and tried to get it to go last week but didnt get much joy. They referred it to Daikin who I’ve heard nothing from since.
Am I missing something obvious? Anyone heard of a heat pump refusing to run because its too hot? Any theories as to why it doesn’t want to work when its hot and sunny?
It has very occasionally done other odd things like a DHW run when not scheduled and not set to reheat. Some odd readings for internal house temperature (28 degrees when it absolutely wasn’t) and phantom rising then rapidly falling tank temperature too but these haven’t happened more than once. The no DHW is a repeating problem that only seems to be linked to the outdoor temperature.
The only help I can offer is a problem we had quite early on with the DHW scheduling misbehaving.
The cure was to delete all the schedules in the app, wait a while, then redo.
It seemed to be that multiple changes in a short space of time confused the app / controller!
I then only entered a single schedule once a day, at 1pm.
I also had problems with the DHW ECO setting being ignored sometimes.
Whereas the comfort setting always worked.
The ECO ignoring thing was confirmed by another user (sorry can recall who).
If I remember correctly the advice was to go LWT only for heating (effectively disabling Madoka) if one wanted the ECO DHW to work properly.
This cured he problem totally.
Not ideal but a workaround.
Never had a problem with it coming on during the cold or recent warmer outside weather.
Usually get over a COP of over 4 too.
In LWT heating mode you can only enter temperature knock back and increases scheduling via the MMI.
The app can monitor and be used to turn off / on the heating (and hot water) as usual.
Since start of May we’ve had the heating off via the app.
If @HeatStig’s suggestions don’t help, I’d suggest looking for a wiring fault, starting around the temperature sensors. Look for bad crimps, or wires not stripped to the correct length meaning the clamp or screw is tightened down onto insulation and not metal, and things like that.
I have a Daikin EDLA 4kw. It sits against the west wall of my house, and there’s a remote thermostat on the north wall out of the sun. I can confirm that if the unit decides it’s too hot, it’ll refuse to run the DHW cycle. More insanely, even though my unit is set to use the remote sensor to determine the external temperature (and does for weather compensation), it’s the sensor on the unit itself that’s used to determine whether it’s too warm to run. I think the cutoff was about 30°C, but I can’t be sure. The sensor on the unit is on the back in a plastic tube, and at certain points of the day during the summer last year it was in direct sunshine, and way hotter than the ambient air temperature. I sat a roof tile over it to give it some shade, and hey presto, hot water. Madness.
Thanks for all the replies. Looks like I’ll have to find for a sun hat for the heat pump then. Maybe a hole in the market for Octopus to fill. Sure they can knock up some fetching pink/purple heat pump sun shields for a post install upgrade or maybe just stick a purple fluffy octopus pen topper toy over the sensor.
I doubt there will be demonstratable consistency with when it’ll run or not. It wouldn’t run last week at 35 degrees but there was no hesitation today at the same temperature.
