On the topic of ratings, have a look at this rating plate for a 5kW ecodan - note the actual maximum is quite a bit higher than the model number suggest. Perhaps mitsubishi are the good guys in this whole mess?
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
On the topic of ratings, have a look at this rating plate for a 5kW ecodan - note the actual maximum is quite a bit higher than the model number suggest. Perhaps mitsubishi are the good guys in this whole mess?
I think you're right. If you believe their numbers (and I don't know of any reason not to) you can see that the badged capacity is available down to -7C ambient and 45C flow, which will cover most of what a UK winter has to offer.
On the topic of ratings, have a look at this rating plate for a 5kW ecodan - note the actual maximum is quite a bit higher than the model number suggest. Perhaps mitsubishi are the good guys in this whole mess?
I think you're right. If you believe their numbers (and I don't know of any reason not to) you can see that the badged capacity is available down to -7C ambient and 45C flow, which will cover most of what a UK winter has to offer.
Encouraging to see them publish such a good collection of data points. Thanks for digging that up.
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
Midea (and no doubt others) do publish this data as well, and their 14kW model can also produce more than 14kW, but only in ideal conditions, when 14kW is not needed, because it is warm outside. The point for me is the real world capacities are not in the headlines, there are buried in ratings plates on machines (which your average consumer will never see until it is too late - you don't go to a Curry's showroom to buy an ASHP) and in hard to find technical data sheets and books. Mr and Mrs Joe Average is not going to choose page 60 of a 442 Ecodan ATW Databook pdf as their bedtime reading. They are far more likely to assume that just as a 2kW convector mains electric heater outputs 2kW when switched on, a 14kW ASHP will output 14kW when it is running. They have been misled, because while it can produce 14kW when it's not needed, in practical real world conditions when sensible heating is required it will never produce its rated output. I thought transparency was supposed to be all the rage these days, and I absolutely cannot see why an ASHP that outputs 11.5kW when it is zero degrees outside cannot have 11.5 in its model number, and is instead allowed to have a higher number. Not only does it make no sense, it is positively harmful, because it is a direct cause of people getting undersized heating systems.
I suppose the alternative is that old standby, better education. If people can grasp that cars achieve different mpgs depending on driving conditions, then maybe it can be made common knowledge that ASHPs are inherently and significantly less capable and less efficient at the lower end of their normal operating conditions, then Mr and Mrs Joe Average might routinely ask about performance in these conditions.
Alternatively, MCS could simply make it a requirement that the data is part of their certification, ie published alongside their SCOP data. Simple, but effective, which means it probably won't happen.
Midea 14kW (for now...) ASHP heating both building and DHW
I think we need better education for consumers (most, my wife included, wouldn’t know what a kW is, they just want to be warm) and better education of installers / specifiers.
The test specifications to EN whatever it is, being at A7/W35 is useless too - fine if you’re heating a ufh slab in a passive house, in Southern Europe…
A-3/W55 is where we should be rating units at.
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
I think that you will find that on this forum we have been making people aware of the shortcomings of ASHP's for approximately 1 Year.
Absolutely, I am one of those who have benefited hugely from the knowledge generously made available here. But I had to seek out the forum. The problem is Joe Public doesn't necessarily ask the questions he/she needs to ask, and not unreasonably (!) assumes professional installers accredited by national bodies know what they are talking about. Before anyone says it, of course some installers are brilliant, but others...
I have just started a new thread with some interesting/depressing depending on your view point statistics on Green Home Grant installations. Something is going horribly wrong, and it probably isn't too hard to figure out why.
Midea 14kW (for now...) ASHP heating both building and DHW
The test specifications to EN whatever it is, being at A7/W35 is useless too - fine if you’re heating a ufh slab in a passive house, in Southern Europe…
A-3/W55 is where we should be rating units at.
Totally agree. A0/W55 might be more intuitive, as most people can relate to at/above/below zero. Also agree about knowing what a kW (and kWh) is, even those in the supposed know struggle sometimes. But making some basic concepts common knowledge would be a good starting point.
Midea 14kW (for now...) ASHP heating both building and DHW
@cathoderay On the subject of derating manufacturers specifications, LG (despite having what appears to be the nicest controller, and the cheapest units when comparing £/kW output), seem to be the worst. Have a look at this screenshot for their 5, 7 & 9kW units
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
Not the most clearly laid out table, I wonder why, and some odd choices for Air/Water values. What about A-2/W55 or W50 - they only give A2/W35, which few retrofit are going to run at. On the figures they do give, I suspect the A-2/W50 or 55 is just downright embarrassing. Its clear they want to obfuscate as much as possible...
Midea 14kW (for now...) ASHP heating both building and DHW
Not the most clearly laid out table, I wonder why, and some odd choices for Air/Water values. What about A-2/W55 or W50 - they only give A2/W35, which few retrofit are going to run at. On the figures they do give, I suspect the A-2/W50 or 55 is just downright embarrassing. Its clear they want to obfuscate as much as possible...
I honestly think that they just 'didn't think that people would need those values' in the table - From following numerous Korean builders on Instagram, it looks like they are building high efficiency, UFH heated, timber framed places, so I doubt retrofit even appeared on their radar.
Or perhaps I'm just giving them the benefit of the doubt.
Either way, I think LG is off my list for now. Back to Midea vs Cool Energy
EDIT: Have you seen these TUV reports? They seem to test at decent temperatures, the defrost requirement is quite interesting:
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
The defrost cycles appear to be a particular nuisance, because they kick in, as I understand it, at around 5 degrees ambient (and stop at minus something, no longer needed for a reason I can't remember) but the key point is they reduce output when it is most needed. Very crudely, again as I understand it, the unit becomes a cooling unit, sucking heat from the house to achieve the defrost. Clever, or what? Again, it is not always clear whether manufacturers include the defrost effect in their output data. If you plot output by ambient, and see a dip around 0 to 5 degrees ambient, that is most likely the defrost cycles kicking in.
What's odd about that TUV (TUV = ?) table is that there is only one column showing a defrost cycle. But it is also the column with the longest data collection period, 4 hours vs 2 hours for the rest. If my 5 degree threshold is correct, the A7 and A12 tests wouldn't have defrost cycles anyway. One way of getting rid of embarrassing defrost effects at lower ambients would be to run tests that last less than the interval between defrost cycles.
I wonder how many installers tell customers that their ASHP will periodically turn itself into a fridge unit in colder weather.
Midea 14kW (for now...) ASHP heating both building and DHW
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