@toodles If it does exactly what you need it to do, that’s perfect function.

@papahuhu The decision as I say, was influenced very heavily by lack of space for a conventional tank. This was installed before any alternatives from Heat Geek might have been considered though I gather they have several offerings now that fit in a smaller space. Regards, Toodles.

@papahuhu @old_scientist  Again today, you may see that I have kept that small thimble measure of hot water for my wife to shower with😉. Regards, Scrooge.

Not that it matters, but those numbers are an impossibility. Therefore the measurement or reporting must have a very large error.

@papahuhu The consumption figures agree with those from the Tesla app and I can even see the sudden rise in consumption when Eddi kicks in and how long it takes to charge so, yes the figures are genuine! The maximum rate of consumption is 3.2 kW and it varies downwards when solar yield drops and as you can see, it is taking less than an hour to complete a charge. Of course, at present, our ‘cold water’ is coming in at a somewhat elevated temperature which must contribute to Scrooge economics. Regards, Toodles.

Please don’t take my manner as condescending, it’s not intended but it is my habit.

So it seems that all your measuring devices are reporting you heat you hot water using a chemical process for 2 persons with 2kWh daily. So, let’s try to use analogy.

Your 2kW kettle boils 1L of water in 4 minutes, let’s assume the starting water was 0C. 
Therefore in 1 hour, using 2 kWh of power, it boils 15L of water.

Therefore that power will give you 30L of water at 50C. 
However that assumes 100% efficiency, at best and being very generous, a chemical phase change might give you 75% efficiency, ie 23L of water at 50C. Not quite a thimble but you aren’t getting 2 showers from that. 

I have no idea why, but the reported numbers must be erroneous by several hundred percent. 

@papahuhu Please remember I did state a range for summer and winter and included the ‘~’ before the figures. It just so happens (probably due to hot weather pre-warming our ‘cold’ water) that the last few days have shown very low consumption. Having said that ~3 - 3.5 kWh is about right for normal summer days. As to meter accuracy, during the winter months when I am using the grid almost entirely (perhaps a few kWh of solar on a sunny day) I have observed the consumption on the Octopus Energy stats too. They all seem to tally and if I deduct my other household consumption and all exported energy, again the figures tally with Eddi’s consumption. If the system is cheating in some way, all metering (inc. the smart meter) are being fooled! I am very pleased that my DHW is defying your calculations then, long may it continue!!!😉 Toodles.

It’s my goal to attempt to be more magnanimous and do it without any sarcasm.  To that end, yes you are absolutely correct and it does indeed generate more energy than it consumes. I may need to practice a little harder.

I am new to heat pump jiggery-pokery and thought I must be stealing something from somewhere!!

You have shown me I am not a proto criminal, so thank you.

180l @ 45c two showering (one properly apparently) and dishes etc.

@papahuhu 😳 As I mentioned, it is a small thimble!😉 We have a Mira shower, our water pressure is nothing to write home (or even to a forum such as this!) about and we struggle to reach the 1.5 bar level on the heat pump system. This flow is enough for a shower though but we don’t stand in there for the duration! We will just have to continue defying the laws of physics I think! Perhaps come the winter, I’ll remember to make a similar reading under more severe conditions and post here. 😆 Regards, Toodles.

@toodles You might have gotten away with a 50L hot water cylinder then, they must make some dinky ones for folks in single occupancy flats.

@papahuhu We might well have found that a much smaller tank would have served our needs; previous to having a heat pump installed we had a gas boiler and the DHW systen bristled with a 99 litre tank. The settings were as far as I could manage arranged to heat the water to a litle lower than 60 deg. C. to reduce the damage from our very hard water supply. We didn’t at any time run the tank out of hot water. Your suggestion of 50 litres may not be that far off the mark!

The reason for the larger tank? MCS! They set the parameters for the guidelines the installer should heed. A ‘four bedroomed’ dwelling requires a 210 litre tank they say. As you may well appreciate, that is a large tank capable of serving four or more occupants! If a room less than two metres square can be regarded as a bedroom, then, yes we have four bedrooms! We wished to accept the Govt. £5K grant so MCS guidelines had to be adhered to. Regards, Toodles.