As it happens, I have been a fairly close eye on things for the last week.

First up, context. Three bed leaky old building in Southern England. Hourly ambient temp from a local Met Office WOW website:

Midea app reported kWh in and kWh out. They are taken from the History pages, not current pages. They are heating only ie not including DHW:

Actual daily figures for heating, DHW, plus totals and COPs:

There are some odd ones in the table eg the 2nd Dec DHW out of 8kWh. You can boil a lot of lobsters with 8kWh. I also suspect the COPs may be creatively high. The Midea App also under records total kWh in - interesting given the speculation is that it always rounds up to the next integer. Perhaps it only records compressor use. Another example perhaps of manufacturers not telling the truth, the whole truth and nothing but the truth.

Now some data on the mysterious Set temp. This looks as though it is meant to be the set, as opposed to actual, LWT. I am currently in always on weather comp mode, 53@-2 / 30@15 settings. Here is the set LWT vs actual LWT, former from the app, latter from twice daily manual obs on the Controller (the LWT has been fairly steady throughout, and compressor was always running when I took the obs). Looks rather random to me:

Nor is the Apps own record of the daily Ambient vs daily Set temp any better. This should approximate a straight line, from top left to bottom right, Set temp goes down as ambient goes up. I don't see that happening: 

  The only caveat is last week only covered a smallish temp range, 5 to 7 degrees, the curve hopefully will be more apparent over a wider range. 

Just for ecodan 11.2k

Wk com 14/11/ 22,  average daily  18.31kwh, average daily temp 8.4 degrees, average daily cost £6.41

Wk com 21/11/22 average daily 23.36kwh, average daily temp 7.4 degrees, average daily cost £8.18

Last wk average daily average 28.97kwh, average daily temp 5.3 degrees, average daily cost £10.14

Running on weather comp
Target room temps 19 degrees, ceramic floor always overshoots rooms 20/21

2 zones
Ufh heating 7 rooms downstairs
5 rads upstairs and 2 heated towel rails

Saved 256kwh over last 3 week compared to last yr.

Posted by: @benseb

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Posted by: @editor

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At 5-10C outside, we easily push 55-60kWh per day. When temperatures tumble to zero and below, we had days in Feb two winters ago where we did over 100kWh. On today's tariffs that's a killer.

 

Ours used to be like that until we de-zoned everything. Much better now 

 

Did you ditch the buffer too?

Posted by: @derek-m

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Posted by: @marvinator80

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These are quite scary amounts of electricity consumption. Is this normal?

The amount of electrical energy used is dependent upon the overall heat loss and how efficient your system is operating, plus of course the none heat pump electrical energy used.

 

Thanks. This is what my system has been designed at after survey.

“9.2 Kw heatloss using current sap and U-values , design temperature of - 5.4 degrees C and room temperature of 21 degrees C and 22 degrees C for bathrooms/cloakrooms .“

I’m hoping my Grant Aerona R32 13KW will be reasonably energy efficient. Have 5.46KW solar array and 10KW battery installed also. 

@editor no kept the buffer

Unfortunately can't see yesterday's consumption figures from Octopus; they're normally pretty good.

Nonetheless...

W/C 20th Nov

Total consumed from grid - 152.1 kWh (avg 21.7 kWh per day, min 15.73 and max 32.99). Of that, ASHP heating accounted for 106.9 kWh (avg 15.3 kWh per day, min 4.2 and max 22) and hot water 26.6 kWh (avg 3.8 kWh per day). Our non-ASHP consumption was 58.8 kWh, averaging 8.4 per day.

W/C 27th Nov

Total consumed from grid - 209.5 kWh (avg 29.9 kWh per day, min 15.73 and max 34.66). Of that, ASHP heating accounted for 121.9 kWh (avg 17.4 kWh per day, min 2.4 and max 25.1) and hot water 37.7 kWh (avg 5.4 kWh per day). Our non-ASHP consumption was 70 kWh, averaging 10 per day.

Obviously this was offset a bit by the solar panels, but not by that much. Over the whole fortnight we only generated 60.3 kWh which is better than a kick up the bum with a spiked boot but only 4.3 kWh per day on average.

Posted by: @majordennisbloodnok

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W/C 27th Nov

Total consumed from grid - 209.5 kWh (avg 29.9 kWh per day, min 15.73 and max 34.66). Of that, ASHP heating accounted for 121.9 kWh (avg 17.4 kWh per day, min 2.4 and max 25.1) and hot water 37.7 kWh (avg 5.4 kWh per day). Our non-ASHP consumption was 70 kWh, averaging 10 per day.

123kWh for the ASHP here that week, 100kWh heating and 23 kWh hot water. Not much idea of non-ASHP because I've still not got Octopus talking to emoncms in a suitable format.

@benseb 

I’m in the process of trying dezoning in our house.  How did you achieve it?   So far I have removed the zone heads for each of the underfloor heating zones, and only have it controlling from the coldest room controller.  All the rest of the controllers are set low enough so they will not set the heat pump off.  Just waiting to see the longer term results now.  

My Midea 8kW heat pump is using about ~15-17kWh a day at the moment. Will be interesting to see how it does with the frost. 

Batteries are earning their keep with this sun today!

Small house of approx 90m2. - Partly renovated and insulated 

Avg 7C Day

Consumption ~14kWh

Avg 4C Day

Consumption ~ 17kWh

These numbers are approx 2kWh high as they include DHW production.

Room Temp 20C however we have used the log burner on some evenings and reduced the heat pump use.

140m2 and heated background circa 18degC daytime 16degC night time. Grant Aerona3 on 24/7. Currently about 24kWh per day for heating and DHW (45degC stat setting on 250l cylinder) combined. Weekly Legionalla boost by immersion on the Solar iBoost. In addition we'll typically consume about 8kWh per day for lighting, small power, cooking, washing machine, etc. So 32kWh per day on average. I think later this week we'll see that creep to nearer to 40kWh as the temperature and CoP plummets and the ASHP defrost cycles start to add up. We have the log burner on low during afternoons and evenings. We use it to dry clothes in preference to a tumble drier.

If I think of what my my wife and I would have been paying 5 days a week in petrol and diesel respectively on our former commutes then we're in pocket even having the heating on 24/7 while we're both mostly WFH.