Posted by: @harriup

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@davidalgarve

My surplus power 'consumed' last year was around 630kWh, so around 1.75kWh every day. Some fairly random variation either side of this, not related to consumption, and certainly not a straightfoward percentage overestimate. A standard deduction would get you closer to the figure, but if you want accuracy then the most cost effective would be a standard electric meter (c£40ish?) that has a pulse output which can be plugged into the FTC controller and will replace the units guesstimates with accurate measurements.

glpinxit

I also spent a long period at first noting down daily figures from the controller - most tedious. But then mastered looking at the code generated by MelCloud in a browser window (in my case Firefox >Tools >Browser Tools >Developer Tools> then Network and Response options) and have managed to create an entire history of the unit's performance in a spreadsheet. This is much more useful to make comprisons with.

I have just been looking at the Ecodan manual for a different reason and remembered your post. So taking your figures of 630kWh last year, that gives 1.726kWh per day, or 71.9178W for each hour.

According to the manual, Water Pump 4 in the Energy Monitor settings has a default value of 72W.

Has anyone checked the settings within their system?

The surplus consumption appears even when the heating is off over the summer, sometimes weirdly high, ie 3kWh - and though there is proportional relationship to the heat generated when the unit does run, it is quite loose.

I have a 20W continuous draw, partly the controller board, but I also suspect the MelCloud wifi module is responsible for some of that. Given that the units can draw several kW of power I think that the lower current draws in particular are not being measured accurately. And Mitsubushi are quite clear that if you want an accurate measure of the energy consumed you should fit a proper meter.

Posted by: @harriup

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The surplus consumption appears even when the heating is off over the summer, sometimes weirdly high, ie 3kWh - and though there is proportional relationship to the heat generated when the unit does run, it is quite loose.

I have a 20W continuous draw, partly the controller board, but I also suspect the MelCloud wifi module is responsible for some of that. Given that the units can draw several kW of power I think that the lower current draws in particular are not being measured accurately. And Mitsubushi are quite clear that if you want an accurate measure of the energy consumed you should fit a proper meter.

I fully appreciate that an external power meter will probably be more accurate than any internal equipment.

The point that I am making is that even an external power meter will only provide truly accurate system power consumption, if all the auxiliary equipment (pumps, valves, heaters etc.) are actually powered via such an external power meter. I assume that the external power meter is monitoring the power being fed to the outside unit. If you have the pre-piped Ecodan water cylinder, the power for the control box can be via the outside unit or from an alternative power supply. If it is from an alternative power supply then the power used by all the equipment connected to the cylinder control box will not be measured by the external power meter. This could be the reason why the external and internal readings differ.

According to my interpretation of the information contained within the manual, the controller can accommodate up to 4 water pumps, and if each of these water pumps had its own dedicated power meter, the controller could accept a power meter reading for each, and collate these values along with all the other power used by the system. In the absence of dedicated power meters for any water pumps, it is possible to set an estimated value of power consumption for each of the 4 possible water pumps that could be installed. The default setting for water pump 4 is 72W, which I assume will be the value used by the controller in its calculations whether pump 4 is installed and is running or not.

I would again suggest that you check the values that have been set within the service menu, covering water pumps and any other equipment that could be using power.