@oswiu - this is something that has come up before (Ecodans having better low temperature performance than Midea units). This is precisely why I suggest MCS include these critical numbers in their database - so that potential customers can be alerted to these varying capabilities, as well as the general fact that all ASHPs are oversold on performance. I naively thought a 14kW unit was, well, a 14kW unit when it mattered, but it's not, it's an 11 point something unit. This marketing is exactly the same as a car manufacturer selling a car as an 140mph car, and omitting to tell you that you will only get 140mph when the car is going downhill with a following wind. On a level road you might get around 120mph, and if it has to go uphill or into a head wind, only 115mph. It's dishonest. It's precisely the sort of thing a regulator with any substance would take strong exception to, and insist that manufacturers not only reveal (which they already do, but in very hidden away places) but highlight the real world performance, and a competent regulator would as a matter of course include these figures in their supposedly impartial open access database. By not including these figures, MCS make cynics like me wonder what their game is. Why don't they want to be up front about real world performance?

I wonder who really pays for MCS? If it is the manufacturers, either directly through membership fees or indirectly through some other route, then one has to wonder how well they will truly represent consumer interests. It might also explain why, and @editor has pointed out, they have a truly terrible record for actually sorting out customer complaints.

Extending my thinking here, I cannot rule out the possibility that MCS are part of some green eco-nut cabal who want to see 'renewables' installed everywhere, even where the sun don't shine, all that matters for them is raw numbers of installations, and they don't give a fig about whether those installations actually work.  

Posted by: @grahamh

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all i care about is what it costs and am i warm, now lets move on. 

I've been thinking about this, because it was a really interesting point - what are my objectives and what things should I care about? Where I've landed is that COP is inextricably linked with "what it costs and am I warm", so we should probably measure COP even if cost and warmth are our sole objectives. It's heat output divided by energy input: heat output determines how warm you are; energy input determines what it costs. COP is a ratio of the two things I'm most interested in, so measuring it seems like a good idea if I care about cost and warmth.

For me personally, I suppose the other reason in addition to "cost and warmth" I want to measure my COP is because I want my system to be efficient and not wasteful, and COP is a measure of efficiency. So for me, I care about more things than just "what it costs and am I warm", and would want to measure my COP even if I was happy with both the warmth and the cost.

On another note, as the forum is called "Renewable Heating Hub", I'd imagine many people here would want to use as little non-renewables as possible. As long as the grid continues to use non-renewables for generation, reducing energy waste and increasing energy efficiency would be a sensible goal for someone who cares about minimising non-renewable energy use. COP would therefore be important for people who have that on their list of objectives.

@cathoderay Easy to find out who is behind MCS. My personal experience so far, and to the detriment of my health, is that any concerned or dissenting voices are quashed due to vested interests. Legitimate questions about design, installs and running costs are constantly stonewalled and I am constantly 'gaslit' (the irony of that term does not escape me). I have discovered the dark side to the industry. It all seriously needs exposing by some good investigative journalism but integrity is in short supply. It literally is get the numbers of installs ramped up, by any deception to the consumer and others necessary. I love this technology. I want to do my bit to save the planet. I just don't want to be the victim of poor design, installs and commissioning and also deceived about the running costs/COPS/SCOPS in the process.

@cathoderay when your heat/loss demand was calculated, it should have shown an assumed flow temp, assumed room temperature, external minimum temperature (mine was designed down to -3C) and hence could the proposed ASHP deliver the required performance and at what SCOP. The power of the ASHP is almost irrelevant. My Daikin Altherma 3H HT is nominally an 18kW unit. But that is 12kW plus 2x 3kW back up heaters (one in the exterior unit and one in the hydrobox). My system is designed to meet 99.8% of demand down to -3C without resorting to the backup heaters. Average winter temperatures for where I live are 5C. So I have headroom. 
And in first year, we only used 56% of the predicted electric usage. I put this down to better insulation in the property than estimated, running the system at a lower flow temperature and only heating the home to 20.5C max. 
This ramble was to explain what happened in my system and what I would expect an installer should supply you to help you make a decision and measure against in the future.

Posted by: @julianc

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@cathoderay when your heat/loss demand was calculated, it should have shown an assumed flow temp, assumed room temperature, external minimum temperature (mine was designed down to -3C) and hence could the proposed ASHP deliver the required performance and at what SCOP. The power of the ASHP is almost irrelevant. My Daikin Altherma 3H HT is nominally an 18kW unit. But that is 12kW plus 2x 3kW back up heaters (one in the exterior unit and one in the hydrobox). My system is designed to meet 99.8% of demand down to -3C without resorting to the backup heaters. Average winter temperatures for where I live are 5C. So I have headroom. 
And in first year, we only used 56% of the predicted electric usage. I put this down to better insulation in the property than estimated, running the system at a lower flow temperature and only heating the home to 20.5C max. 
This ramble was to explain what happened in my system and what I would expect an installer should supply you to help you make a decision and measure against in the future.

They shouldn't badge it as an 18kW ASHP if that's what they do.  But in your case it's fine because the installer/designer did a good job.  Unfortunately what happens sometimes is that less competent installers assume the badged output is available from the ASHP (and not a back up heater) when it's really needed. 

We have a combination of (1)incompetent installers and (2) complicit manufacturers.  Guess who gets left with a cold house and big bills?  A clue; it's not (1) or (2)...

@kev-m yes. Sorry to hear this Kev. If the installer won’t help, MCS won’t help, can you go to citizens advice and say the solution is not fit for purpose? 
Looking on the MCS website, there is a process if something goes wrong.
1.  Complain to your installer formally in a letter.
2. And a form on MCS.
Has this process been followed?

There are then processes after this if you are not satisfied  Lots of extra work I’m afraid, but it’s a large expense 

Good luck 

@julianc - yes, I had all the calculations assumptions etc, room by room and total heat loss at -2 outside/design temps inside, and the problem is that the Freedom Calculator over-estimates the Midea's output at lower outside temps. In my case, I had effectively zero headroom on the calculator - 12.3kW heat loss, 12.4kW (claimed) from the heat pump, but the more realistic output is nearer 11.5kW so at -2 outside my system is going to struggle, to put it politely.

Posted by: @julianc

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The power of the ASHP is almost irrelevant.

I'm not sure I agree. If the building loses 12.3kW, and the heat pump supplies less power, then the the rooms won't get up to temp at design conditions. It's simple thermodynamics, if the loss is greater than the input, then the house will be colder than it should be. It's that simple. OK, its a bit more complicated, the heat pump supplies the heat, the distribution system, pumps pipes and rads, then has to transmit it to the house, and then the house loses it to the environment, all parts of the chain need to be able to do what they need to do, but the bottom line remains the same, a 10kW heat pump will never get a 12kW heat loss building up to temp at design conditions. To that extent, the power (output) of the heat pump does matter, rather fundamentally.

Posted by: @kev-m

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They shouldn't badge it as an 18kW ASHP if that's what they do.

I agree, it's misleading, that's the first problem, and the follow on problems are as you say.

Posted by: @julianc

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Sorry to hear this Kev.

I'm sure Kev was talking generally. There are tales of woe all over the forum, and no doubt many others that don't get told here, just as there are tales of double woe on woe, MCS being toothless and ineffective. Perhaps it's time to invite those who have had MCS successfully sort out a complaint to give an account of what happened.

Posted by: @grahamh

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i think its hilarious that our industry worries about cop when all that matters is run cost. The pumps are there to do a job, they would be there if you had a boiler too. The boiler lads dont take any electrical consumption into consideration when talking about efficiency and despite what you are told neither do the heat pumps. The cop your machine measures is just for the compressor, no pumps, valves, controls nothing else is measured. Get over it. its so bloody dull. 

all i care about is what it costs and am i warm, now lets move on.

Whilst I understand many of your sentiments, I have to disagree with your wording.

As I have mentioned elsewhere on this thread, I care about other things as well as warmth and running costs. In essence, all I care about is how effectively the heat pump is fulfilling all its promises; that includes what you said, but other things besides, like impact on the environment.

It worries me when you talk about warmth and cost as the only criteria since by those benchmarks many people may feel justified in deciding a gas boiler meets those points and bugger the impact on the planet. We already hear plenty of arguments that heat pumps are no good for heating badly insulated homes, which, reworded, implies excessive use of a boiler is an acceptable alternative to making one’s house more energy efficient. It’s the wrong way round, and throwing more energy at a problem should only be a last resort.

COP may be dull and boring but it is one of several measurements to give me and others like me an idea of how well my heating system is doing what it was bought for, so regular real-world data collection should be made as accessible as possible.

Posted by: @julianc

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@mjr sorry to hear that. Can you contact the ASHP manufacturer?  They will want a good installation

Mitsubishi don't answer me. I've managed to get the system working pretty well with help from this forum and another and may be able to complete the installation finishing touches early in the new year. 

Posted by: @cathoderay

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@julianc - yes, I had all the calculations assumptions etc, room by room and total heat loss at -2 outside/design temps inside, and the problem is that the Freedom Calculator over-estimates the Midea's output at lower outside temps. In my case, I had effectively zero headroom on the calculator - 12.3kW heat loss, 12.4kW (claimed) from the heat pump, but the more realistic output is nearer 11.5kW so at -2 outside my system is going to struggle, to put it politely.

Posted by: @julianc

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The power of the ASHP is almost irrelevant.

I'm not sure I agree. If the building loses 12.3kW, and the heat pump supplies less power, then the the rooms won't get up to temp at design conditions. It's simple thermodynamics, if the loss is greater than the input, then the house will be colder than it should be. It's that simple. OK, its a bit more complicated, the heat pump supplies the heat, the distribution system, pumps pipes and rads, then has to transmit it to the house, and then the house loses it to the environment, all parts of the chain need to be able to do what they need to do, but the bottom line remains the same, a 10kW heat pump will never get a 12kW heat loss building up to temp at design conditions. To that extent, the power (output) of the heat pump does matter, rather fundamentally.

Posted by: @kev-m

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They shouldn't badge it as an 18kW ASHP if that's what they do.

I agree, it's misleading, that's the first problem, and the follow on problems are as you say.

Posted by: @julianc

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Sorry to hear this Kev.

I'm sure Kev was talking generally. There are tales of woe all over the forum, and no doubt many others that don't get told here, just as there are tales of double woe on woe, MCS being toothless and ineffective. Perhaps it's time to invite those who have had MCS successfully sort out a complaint to give an account of what happened.  

  

Yes I was using the royal 'we'. My own experience is positive. Reading back what I said I can see that it could have implied otherwise! 

Posted by: @mjr

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Posted by: @julianc

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@mjr sorry to hear that. Can you contact the ASHP manufacturer?  They will want a good installation

Mitsubishi don't answer me. I've managed to get the system working pretty well with help from this forum and another and may be able to complete the installation finishing touches early in the new year. 

Have you tried the support like on 0161 866 6064?  I'm not saying they'll be able to help but I have called them a couple of times recently and they did answer.

I have read some ill informed rubbish in my time but this thread is world class.

First I wrote the freedom calculator. The data is fine. I owned Freedom heatpumps until a few weeks ago. We knew and still do know what we were / are doing.

MCs calculations of all kinds encourage oversizing. So if your calculation is tight there is loads of head room.

The model number of the unit bears no relevance to the actual kWs you get. So we, the professional designers plot your load v.s the output of your chosen unit.

Mitsubishi don't perform better than any other unit. They are a very average unit. Nothing special at all. They just give their output and ignore defrost. Turns out it's a clever thing to do as MCS oversizes everything.

And yes I do have loads of evidence to back this up. 

If you need help have you considered paying someone who knows what they are doing? Asking keyboard warriors on the web is a great way to get shit advice.

I can see why I no longer get involved in after sales. Bloody tedious.