@derek-m If you want to go the DIY route, I would suggest https://guide.openenergymonitor.org/applications/heatpump/

I am personally considering this, but now I have found my app does power and heat delivered via its own meters, it seems less important. The only issue I do have is a total lack of minute by minute clarity over the data and limited look back; except for whole day data.

@kev-m Good morning Kev,

I had a closer look at your 091121Graph2 and noticed some interesting things.

Looking at the graph I suspect the following sequence of events occurs within your ASHP.

You will notice that the energy consumed trend exhibits a sawtooth at the bottom of the graph when the compressor and fan are not running. I believe this is the water pump being periodically run to check the changes in the flow and return temperatures.

When the flow temperature falls to the value requested by the weather compensation, the compressor is started and water pump is run continuously.

After a minute or more of compressor operation, the pressure and temperature of the refrigerant gas in the condenser has increased to a point where the water is being heated, and gas is flowing through the expansion valve into the evaporator.

At this point it would appear that the fan is started and ambient air is drawn through the ASHP. This flow of air would appear to be detected by the ambient air temperature sensor, which indicates a 1C drop in temperature.

When the water flow temperature has reached the required value, the compressor is stopped, but the fan and water pump continue to operate.

Probably, when the gas pressure has reduced to a predetermined level, the fan and water pump are stopped and the system reverts to the periodic running of the water pump to check the flow temperature.

I hope that this makes sense. If one understands how a system is designed to operate, it makes fault finding much easier when the system does not operate as expected.

@derek-m,

that makes sense.  I did notice the outside temp being affected by the ASHP running and assumed the same. It's only ever 1C so not going to make a lot of difference. 

The return and flow pumps have a maximum power consumption of just under 60W, which corresponds to the numbers behind the 'sawtooth'.   

Update, 11.6kW used 10/11/21.  House temp still 21C.  I'll leave things as they are for now.   

Update, 12.1kW used 11/11/21.  House temp still 21-22C.  No change, weather looks similar for the next few days.   

@kev-m whats the size of your house?

Posted by: @batalto

@kev-m whats the size of your house?

Oh dear, your'e not comparing sizes are you?

@derek-m trying to understand what 11kw means. If the house is 70m2 it seems a lot. I used 17kw yesterday to achieve the same results, but my house is 260m2 - so I am using 65w per m2 to heat my house to 21 when the ambient is 13 degrees.

It would be interesting to see others w/m2 of power use and it would provide a levelling which allows us to compare relative performance between houses.

Posted by: @batalto

@derek-m trying to understand what 11kw means. If the house is 70m2 it seems a lot. I used 17kw yesterday to achieve the same results, but my house is 260m2 - so I am using 65w per m2 to heat my house to 21 when the ambient is 13 degrees.

It would be interesting to see others w/m2 of power use and it would provide a levelling which allows us to compare relative performance between houses.

Sorry Batalto,

I'm afraid my dry sense of humour is an acquired taste. As you are no doubt aware, men are always trying to educate women 'that size does not matter'!!!!!

Actually, comparing heat demand per property size, could be a good guide to level of insulation and how airtight the property may be. 

@derek-m its basically a real world heat loss calculation / EPC - I could work our heat loss per average ambient by keeping a log

@kev-m Try to drop the temperature in the house to 19-20. It will significantly reduce the energy used and will have little impact on comfort, (hide the thermometer), It does appear, looking at the graphs, you may have a low flow problem which may be rectified if you replace the valves.

Posted by: @batalto

@derek-m its basically a real world heat loss calculation / EPC - I could work our heat loss per average ambient by keeping a log

Batalto,

I do believe your heat loss would be given by heat pump output power per m2, since the input power would be dependent upon how efficient your heat pump is performing.

If you look at the spreadsheet that I sent back to you, based on the Midea 12kW data that you supplied, you will see the heat loss should be in the order of 4kWh at an ambient temperature of 10C.