Miraculously, the current actual IAT is only 1.4 degrees below the desired IAT. But just look at those defrosts, and the LWT when it does get up to temperature, not to mention the hourly energy use, and a COP that drops to 1.49.
What is the actual temperature at the radiators and what is the temperature drop across the PHE?
@derek-m During the first 14 hours of today, (Tuesday 16th. Jan.) we have kept pretty well to target temperature of 22.5 C. throughout the 4 bedroomed semi detached house using 24 kW/h up until 14:00; I say pretty well, the lowest reading was 21.7 at about 07:00 in the living room but an hour or two later, this was back to 22.5 C. Allowing for perhaps 10% losses through charge and discharge of the battery, this means we have consumed approx. 27 kW/h during those 14 hours @ Cosy cheapest rate. I am quite pleased with that performance. Daikin 8kW EDL08 Monobloc - DHW is independent of this; it is space heating only. Regards, Toodles.
Toodles, he heats his home with cold draughts and cooks his food with magnets.
The defrost temperature (light blue line) is fairly steady around -10C.
what do you mean by the "defrost temperature"? I don't quite follow.
If my understanding is correct, it may be the temperature to which the refrigerant gas falls within the evaporator before the build-up of ice is sufficient to require a defrost to be performed. A lower defrost temperature should therefore indicate that there has been a slower build-up of ice due to there being less moisture in the ambient air.
What is the actual temperature at the radiators and what is the temperature drop across the PHE?
At the moment (just measured), rads ~47, primary in 53, secondary out 54 degrees (not a typo, either measurement error or some sort of lag effect perhaps? Both just about too hot to touch for any length of time). Here is the temp chart for the last hour and a half:
Midea 14kW (for now...) ASHP heating both building and DHW
@derek-m@iancalderbank In the Grant/Chofu docs it's referred to as 'defrost temperature', so that's what Ive labelled it. I'm guessing it's a temperature sensor somewhere close to the expelled air-flow from the HP i.e. when the HP is 'off' it tracks OAT fairly closely; when running, it's much lower than OAT, as shown. Initially I thought it would be a constant (i.e. "the temperature point below which a defrost cycle is required") but observation has disproved that.
@mikefl I think I’m getting the hang of interpreting the graphs now and it seems that the pump has gone through 6 defrost cycles so far today (just under 16 hours worth anyway).
Toodles, he heats his home with cold draughts and cooks his food with magnets.
@ghayneThank you ghayne, i think I’ll ‘make do’ with an approximation as provided by the Govee units, the indoor humidity levels obviously do matter and we are fairly comfortable as we are so I don’t think we need to chase greater accuracy for this purpose. Now when it comes to what the heat pump is being exposed to, I suspect the measurement method used is probably equally ‘ish’, I note that my Homely graph for midnight to this afternoon shows 4 ‘defrost cycles’ though I think the air has been somewhat dryer today. I am not sure how to read the plot for the ‘defrost’ (top trace on this graph) if any reader is able to throw any light on how to read the scale, I would be very grateful; I think the layout is still a work in progress so maybe it is just a relative indication. Regards, Toodles.
Toodles, he heats his home with cold draughts and cooks his food with magnets.
I am not sure how to read the plot for the ‘defrost’ (top trace on this graph)
That seems very high! Did you see the screenshots I posted earlier? my defrost temperatures are much lower (except during defrosting. Hang on I'll post one again!
@ghayne As I say, I think the Homely graphs are ‘a work in progress’ and suspect that the humidity trace needs a line with its’ own parameters! Regards, Toodles.
Toodles, he heats his home with cold draughts and cooks his food with magnets.
I think the Carel platform just calls this ‘coil temperature’…. It’s always below ambient when in heating mode, unless it has just done a defrost.
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
