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Well the heating has been on - possibly didn't really need it but I wanted to try it out. Given it's not particularly cold, the software has compensated for that and runs the HP at super low flows and temperatures. Basically the rads are just about lukewarm at the top - but the house is still fine even in the mornings, because it's got the timing right. In fact, the house is 20C or thereabouts all day, and we haven't been able to even tell what it's doing unless I actually go in and check. I'm highly impressed. It's using maybe 3-500W when running as far as I can tell from the home consumption, and currently about 2kWh a day or 50p
Right, well we've had the first cold snap. Last night when it was -2C or so here, it was consuming about 1.5kW between midnight and 6am, however the previous night it was only about 500W? Not sure what happened there. It may have been a little colder last night than the night before but 3x as much power consumption seems odd.
With some very rough calculations it looks like it's going to come in at a similar cost to the gas boiler. I've got it running at the same temperature all day and night, with no set-back, because if I do this the highest consumption is midnight-6am and we have cheap rate due to the EV tariff.
Keep posting even if no-one is replying, Molgrips, I'm following with interest.
The COP is temperature and humidity dependant. Once you have the condtions for icing you heat pump will be reversing and heating outside for periods. So COP falling along with a bigger temperature difference might explain the increase in energy consumption. Still not bad though1.5kW for a cold night. Given how cheap your EV rate is I'd be tempted to superheat the house over night and benefit from the thermal inertia in the first part of the day.
There was certainly ice on the heat exchanger this morning when there wasn't last night. I don't know anything about the de-icing since Daikin don't really tell you anything of use except the consumption in 2-hourly chunks, and there was a fair old spike this morning. I don't know what the flow and return temperatures are, it won't tell me.
I don't think I want to super-heat the house since it'll get too warm to sleep. I already turn the radiator off in the bedroom at night and turn it on in the morning. I am going to get a smart TRV to automate this.
I am seriously thinking about getting one installed. If nothing else, it should be cheaper to run than the three oil-filled radiators that currently keep the ground floor of the house warm. The upstairs will warm up a bit by natural heating and I'm not that worried about it. The cost is another matter, although I can claim some money back from tax for the time/labour of the installation.
I'd really be ok with a lounge/kitchen that would stay a near constant 19c over winter instead of constantly fluctuating.