I am using Home Assistant's utility meters, so they add up the relevant data based on live readings, to make up the daily, weekly, monthly and yearly data. These will eventually get better, as right now it doesn't have a whole month worth of data, or a year.
The handicap is that it is still using the Heat Pump sensors, as it is connected to it via WiFi, and every now and then, Samsung wants HA to re-authenticate, which will cause a gap in the data, unless I can pick it up straight away.
In effect you are relying on the manufacturer marking their own homework. Is there any way you can validate these readings? For example, I have an independent kWh meter that supplies only the heat pump, that I use to validate my modbus collected kWh in data, and yes, there is a discrepancy, the modbus/Midea data is an under-estimate, possibly because that data is just for the compressor, excluding ancillaries like the circulating pump. The discrepancy is reasonably stable over long periods of time, and I deal with it by using a 'discrepancy correction factor' in my calculations to bring the calculated kWh figures into line with the independent kWh meter figures.
I do think you need to get to the bottom of the discrepancies in the earlier image you posted where the daily and weekly totals are significantly less than the sum of the parts. I presume these are energy inputs, can you also do the same checks on energy out data (which I believe you have access to, based on your earlier posts)? It may throw some light on why your COPs are low. GIGO and all that...
Midea 14kW (for now...) ASHP heating both building and DHW
No. 12kW is obviously the maximum heating capacity (at certain conditions, dependent on manufacturer) but the actual maximum consumption will be much lower than that. I think our 12kW max power input is around 5kW. You can get the figures for yours from the technical bulletin, data sheet etc.
This is all part of the smoke and mirrors around heat pump marketing. My unit is badged as a 14kW unit, but the maximum it has ever put out is 11.52kW. The problem is that while it may be able to put out 14kW on a sunny spring day, in practice it never does, because I don't need 14kW to heat the house in those conditions. When it is much colder outside, and I could do with a few more kW, the heat pump performance is compromised by the lower outside temperatures, and cannot reach it's badged output. As it happens, 11.52kW is pretty close to the tabulated output in the Midea Engineering Data manual at around zero degrees outside, but that is cold comfort so to speak for the disappointed owner who thought he or she might have had a 14kW heat pump.
It's the same as selling a car as an 100mph car and not mentioning that only happens going downhill with a following wind. Going uphill with a head wind is a rather different story...
Midea 14kW (for now...) ASHP heating both building and DHW
@cathoderay I think this was a different point unless I've misunderstood. DREI was asking about the actual power input to the unit itself and whether this meant, for example, a 12kW unit actually consumes 12kW (which it doesn't). Midea do indeed use some slightly misleading test conditions, some might say, to give their power output rating. Personally speaking I wasn't overly bothered as it is what it is and we just consulted the data sheets.
. As it happens, 11.52kW is pretty close to the tabulated output in the Midea Engineering Data manual at around zero degrees outside
I think the first comment is a little unfair. The thermodynamics mean that heat pump output inevitably varies with OAT and FT. The only way to circumvent this is artificially restrict the output in firmware, which some manufacturers do, but honestly what's the point as it simply restricts the use unnecessarily?
The manufacturer has to give the model a name and ideally one which are least tells the designer something about the output to point her in the right direction. What are they supposed to do in this circumstance?
So long as the name is in the right ballpark and the engineering data is published and correct, it seems to me that what they do is fair enough.
for example, a 12kW unit actually consumes 12kW (which it doesn't).
I agree, the badge rating is about output, and I think @drei's recent posts showed inputs, which is why I asked about outputs, and thereby COPs. Recall, if I am not mistaken, one of @drei's chief concerns is low COP values. But if the energy in or out are out of whack, then the COP will also be out of whack.
Midea 14kW (for now...) ASHP heating both building and DHW
The thermodynamics mean that heat pump output inevitably varies with OAT and FT.
The thing is most people aren't physicists. If they buy an 100mph car, they expect it to go 100mph. I've suggested many times that the standard conditions used to describe heat pump outputs should be close to the conditions when real output really matters. Various flow temps at zero degrees OAT for the UK for example. My heat pump might then be badged as a far more realistic 11.5kW heat pump. The fact it can do 14kW on a day when I don't need 14kW is neither here nor there.
I agree the data is usually there for the designer who knows where to look for it, and cares to do so, but I think we know not all of them do that. But this is really about managing expectations for the buyer, not the designer.
Midea 14kW (for now...) ASHP heating both building and DHW
Not 100% accurate, but it is better than we I had, and I made the power level to a maximum of 8kW and red over 6kW, no idea if the HP would even reach that but, if it is a 12kW Heat Pump, does it mean that it can draw 12kW electricity at maximum usage?
No. 12kW is obviously the maximum heating capacity (at certain conditions, dependent on manufacturer) but the actual maximum consumption will be much lower than that. I think our 12kW max power input is around 5kW. You can get the figures for yours from the technical bulletin, data sheet etc.
Good to know, if you have a look at that screenshot you might be able to see, hot water hit a maximum of 4.68kW and heating it reached 5.5kW.
I am using Home Assistant's utility meters, so they add up the relevant data based on live readings, to make up the daily, weekly, monthly and yearly data. These will eventually get better, as right now it doesn't have a whole month worth of data, or a year.
The handicap is that it is still using the Heat Pump sensors, as it is connected to it via WiFi, and every now and then, Samsung wants HA to re-authenticate, which will cause a gap in the data, unless I can pick it up straight away.
In effect you are relying on the manufacturer marking their own homework. Is there any way you can validate these readings? For example, I have an independent kWh meter that supplies only the heat pump, that I use to validate my modbus collected kWh in data, and yes, there is a discrepancy, the modbus/Midea data is an under-estimate, possibly because that data is just for the compressor, excluding ancillaries like the circulating pump. The discrepancy is reasonably stable over long periods of time, and I deal with it by using a 'discrepancy correction factor' in my calculations to bring the calculated kWh figures into line with the independent kWh meter figures.
I do think you need to get to the bottom of the discrepancies in the earlier image you posted where the daily and weekly totals are significantly less than the sum of the parts. I presume these are energy inputs, can you also do the same checks on energy out data (which I believe you have access to, based on your earlier posts)? It may throw some light on why your COPs are low. GIGO and all that...
Part of the remedial work, whenever I get the green light and it commences, I will ask the installers to replace the fuses on the heat pump with the same ones I have on my solar, micro meters. Hopefully that will help.
I can see what you mean, somehow the Heating comes up a lot more, and when added together they are way above what the heat pump usage is.
when added together they are way above what the heat pump usage is.
Which tells us something (including possibly everything) is not right. can you describe exactly how the data gets from wherever it originates to this set of results (the one you posted earlier):
The more I look at it the less sense it makes. I have now just noticed the top panel, under a heading which says 'Energy split - totals' has both heat pump power and hot water and space heating energy, while the units for all three are kW (power). The middle and lower panels appear to be energy (in kWh) but they don't add up correctly. I presume they (middle and bottom panels) are all energy in, but even that is not 100% clear.
Just a reminder: power, measured here in kW is a measure of how powerful something is, or if it is not in use, how powerful it is capable of being. A 2kW conventional electric heater is twice as powerful as a 1kW conventional electric heater, while energy (in kWh) is what is used up (and so has to be paid for) to get something done, in this case heat a room. If you run the 2kW conventional electric heater you will use 2kW x 1 hour = 2kWh of energy, if you run the 1kWh conventional electric heater for an hour you will use 1kW x 1 hour = 1 kWh of energy. But if you then run it for another hour, making two hours in total, you will have used 1kW of power x 2 hours = 2kWh.
Midea 14kW (for now...) ASHP heating both building and DHW
when added together they are way above what the heat pump usage is.
Which tells us something (including possibly everything) is not right. can you describe exactly how the data gets from wherever it originates to this set of results (the one you posted earlier):
The more I look at it the less sense it makes. I have now just noticed the top panel, under a heading which says 'Energy split - totals' has both heat pump power and hot water and space heating energy, while the units for all three are kW (power). The middle and lower panels appear to be energy (in kWh) but they don't add up correctly. I presume they (middle and bottom panels) are all energy in, but even that is not 100% clear.
Just a reminder: power, measured here in kW is a measure of how powerful something is, or if it is not in use, how powerful it is capable of being. A 2kW conventional electric heater is twice as powerful as a 1kW conventional electric heater, while energy (in kWh) is what is used up (and so has to be paid for) to get something done, in this case heat a room. If you run the 2kW conventional electric heater you will use 2kW x 1 hour = 2kWh of energy, if you run the 1kWh conventional electric heater for an hour you will use 1kW x 1 hour = 1 kWh of energy. But if you then run it for another hour, making two hours in total, you will have used 1kW of power x 2 hours = 2kWh.
At this point, I will work on refining the code. But ignore it for now, as this is me writing code, to work out the two different usages and the total based on sensors provided by the heat pump. It's all code and algorithm, not a sure thing. I was happy and posted it, because I thought I was smart:)))
Anyhow, something worth writing about, over the past two months, I’ve observed a significant improvement in system performance. The measured COP has increased from approximately 2.2 to 2.6, despite no hardware changes being made. This is the highest I've EVER had it.
The only adjustment was:
Reducing the speed of the circulation pump feeding the buffer to its lowest setting.
This simple change appears to have reduced the hydraulic distortion (previously a 10 °C loss between the heat pump flow and radiator flow). Thermal surface scans now show flow temperatures around 44 °C and returns 38–40 °C, meaning the energy delivered to the emitters now matches expected ΔT values.
This confirms that the existing buffer configuration, circulation pumps and radiators are the main culprits, but more specifically the buffer configuration alone. Once the remedial works are completed: re-piping the buffer into a volumiser configuration, replacing or repositioning the circulation pump, and upgrading the radiators. I’m confident the system could reach a seasonal COP of 3.0 to 3.5, anything better than that would be an achievement.
This post was modified 3 weeks ago 4 times by DREI
At this point, I will work on refining that. But ignore it for now, as this is me writing code, to work out the two different usages and the total. It's all code and algorithm, not an automatic thing.
If you care to post the code, we can have a look at it. Simple python should not be complicated...
I've done a thermal surface scan, and the flow is at 44 and the return around 38-40.
That's OK, assuming the thermal scanner is accurate. They normally have an emissivity setting, because different surfaces 'emiss' at different values. It may be the absolute values are out about, but the relative ones are OK (ie delta t is 4-6 which is OK).
I actually believe now, even more than before, that once they replace the circulation pump, or move the one pumping into the buffer, and turning the buffer into a volumiser, plus the upgraded radiators, I can easily achieve 3.5, or at least 3, which is what I want. Anything higher will be an achievement.
I agree, it is the physical changes to the system that are needed now, then see what happens to the temperatures and COP, assuming you have code that does that correctly.
Midea 14kW (for now...) ASHP heating both building and DHW
