Posted by: @cathoderay

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I'm asking what is the equivalent data/display from a Shelley so called 'integrated power meter', given that what we actually want to measure and record is energy use over time (kWh use per hour/day/whatever).

The Shelly provide “Current” (amp), “Power” (watt) and “Voltage” (V) for the current state and “Total energy” (kWh) as a counter since the last reset. I suspect that the device you referred does (almost) the same. 

For myself the reason to use the Shelly devices is that they integrate perfectly with Home Assistent.

Posted by: @majordennisbloodnok

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doing what it says on the tin

But what does it actually say on the tin, in words that a thicko like me can understand? Having read most of the Shelly web page linked to above, I am none the wiser.

The Eastron meter has a visual cumulative kWh used display I can read manually, with a modbus option for getting the same kWh data into HA or whatever. What I am asking for is a similar description of what a Shelley device can do. If anyone can add pros and cons of the two devices, so much the better. 

Posted by: @mosibi

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The Shelly provide “Current” (amp), “Power” (watt) and “Voltage” (V) for the current state and “Total energy” (kWh) as a counter since the last reset. I suspect that the device you referred does (almost) the same. 

For myself the reason to use the Shelly devices is that they integrate perfectly with Home Assistent.

Thanks, that is exactly what I was hoping for (and apologies for my immediate past comment, posted before I saw your reply).

In summary, the two are different ways of doing almost but not quite the same thing. The differences are the Shelley device has more variables, and more ways of communicating, but doesn't have modbus.  

@mosibi are you able to give an idea of how inaccurate the midea consumption data is at all ie how your Shelly data compares to what the control panel indicates?

Ah, understood. @cathoderay.

Eventually, the two are not the same product. The Eastron is a meter pure and simple whilst the Shelly is a smart switch with metering capabilities. That, I suspect, is why the Eastron has a display. Shelly does also have a range of energy meters but once again the emphasis is on the IoT idea of data being crunched elsewhere so none of them have a display. For simple displaying of the information one would be relying on the app or a link with another system such as Home Assistant.

For simplicity, I suspect the Eastron would be the ideal. For meters feeding into a central point Shelly energy monitors might be a good alternative. For monitoring a single outlet, something like the EM Mini Gen4 (which can be installed behind the socket) or for monitoring something beefier - a heat pump, for example - something up to the Pro 3EM 120A. None, as you say, does modbus though, although the range of other communication methods is wide.

Posted by: @benson

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are you able to give an idea of how inaccurate the midea consumption data is at all ie how your Shelly data compares to what the control panel indicates?

I can't do it for a Shelley device, but I can for Eastron kWh meter - the Midea energy in data is an underestimate of the total energy in to the heat pump, as measured by the Eastron meter, by a factor of around 1.18 (ie I have to, and do, multiply the Midea reported data by 1.18 to get it approximate to the Eastron value), and it is the up-rated value I use for my COP calculations. I have assumed without any real evidence that the extra energy is used by ancillaries eg the circulating pump.    

@majordennisbloodnok — thanks, a useful expansion on the pros and cons.

@benson I checked the last week of data and i must say that is pretty accurate in those days, where the Shelly measures for example 4.65, the heat pump states 5 kWh. But this is only a quick check, to have a better insight, more data is needed.

I would not be surprised that with more data I would have something in line with what @cathoderay states.

Posted by: @mosibi

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@benson I checked the last week of data and i must say that is pretty accurate in those days, where the Shelly measures for example 4.65, the heat pump states 5 kWh. But this is only a quick check, to have a better insight, more data is needed.

I would not be surprised that with more data I would have something in line with what @cathoderay states.

I have just looked at my heat pump 'long interval' (27 March 2023, because that is when I started full monitoring, to 3 Nov 2025) energy in data as measured by (a) the external Eastron kWh meter and (b) the Midea total cumulative kWh in data and (c) my calculated (minute by minute volts x amps) energy in data they are not that far apart:

Eastron total: 15883 kWh

Midea cumulative total: 14955 kWh

Calculated total: 15176 kWh

Assuming the Eastron is the correct value, then my calculated value is out by a factor of 1.046574303 (ie needs to be multiplied by that number to get the Eastron value), ie it is pretty close, within about 5%. The Midea cumulative total is less accurate, but still not too bad, within 6%.  

Hi all - haven't been on here for a while as I was in ASHP monitoring mode although I still don't have great data and it's generally been a bit too warm for good test conditions. All I can feel fairly confident about is that the estimated heat loss of 14kW is (no surprise) overstated and probably by 15-20%. I think reality is in the 11-12kW range. 

I have been "fighting off" my original installer's desire to fit a 20kW cascade and their other option was a Grant R32 17kW which I still think is way oversized. I suggested the Grant 15.5kW 290 but now I see that the regs on siting of the 290 heat pumps is very restrictive and may not work with our building/plot layout, in particular the requirement to have 1m clearance around the pump. So much more risky than propane tanks!

Of course, my original installer is making life difficult by insisting that they will only fit an ASHP with a minimum output of 14kW (to match the estimated heat loss) at -5C and 50C flow temperature, which they claim are MCS requirements. They have no interest in what the actual heat loss from monitoring is, which is very frustrating.

Anyone have datasheets for their heat pump, which show that the published data notes at least 14kW at -5/50C? I'm struggling to find alternatives and considering just asking them for a partial refund (cost of ASHP and installation of pipework) and getting my own choice of installer and system but no idea whether they will consider that. I assume there are lots of examples on here of ASHPs that are massively oversized due to installer reliance on predicted, over-estimated heat loss calcs but that redress is like banging your head against a buffer tank? A classic tale of installer impracticality and veering from undersizing to massive oversizing.

Regards

Posted by: @pash44pump

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 the requirement to have 1m clearance around the pump. So much more risky than propane tanks!

For clarity there is no requirement for clearance behind (other than for airflow of course - typically 200-300mm) and you can have a window directly above so long as no opening part is lower than the top of the pump casing.

Posted by: @pash44pump

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They have no interest in what the actual heat loss from monitoring is, which is very frustrating.

If it matters in your case, find another installer!

Posted by: @pash44pump

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I assume there are lots of examples on here of ASHPs that are massively oversized due to installer reliance on predicted, over-estimated heat loss calcs but that redress is like banging your head against a buffer tank

Yes there are and many installers are immovable. 

Posted by: @pash44pump

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at -5C and 50C 

Why 50C, is that what the emitters are designed for (lower would be better, and may open up another heat pump or 2)

Posted by: @pash44pump

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Anyone have datasheets for their heat pump, which show that the published data notes at least 14kW at -5/50C?

Obvious one I know of is the Mitsubishi, here is the R32 datasheet, they also do R290 of course. Samsung R290 also https://midsummerwholesale.co.uk/pdfs/samsung-r290-capacity-table.pdf, Bosch also; have a look on the Midsummer Wholesale site they seem to publish the capacity tables which can be tricky to find on manufacturers websites.  There are definitely alternatives to the Grant!

@jamespa thank you. The "incentive" for using the original installer is that because they accept that they put in an undersized HP at the outset, they have agreed to replace it with a new HP at their cost (kit and installation). The downside is that they are being prescriptive on what they want to fit so I'm trying to find a reasonable compromise. 

Regards

Also installers are insisting on min 14kW output at -5C/50C because that's what the heat loss estimate parameters were 🙄