Posted by: @batalto

@majordennisbloodnok exactly. Very few things you actually buy direct from the supplier. I'm surprised people take it so personally.

I see it as an appliance, and Freedom are the UK agent. An agent exists to sell products to users of said product.

No different to buying any other appliance from AO or similar.

I can buy any other manufacturers product just by adding it to my basket and waiting for it to show up on a pallet, why should freedom be any different with the Midea line?

@hughf except you aren't the customer, the fitter/plumber/installer is. You are the customers, customer (the end user). A better example is car engine parts, most get sold to garages, not to end customers. Sure, there are some people who want to buy them direct, but it's a tiny minority. 

Freedom won't care as it's not their business model/strategy to supply end customers. It's easier to manage 200 customers and let each of them deal with 200 end users than it is to set up support for 40,000 customers - all of who will want help with every little setting. Constant calls and emails. Better to leave it to the fitters and just supply/train them.

If you want to fit your own heat pump you are very much the exception to the rule. But the same would be true of most heating/plumbing work. Most people would rather get someone in because they don't see a heating system as a fridge (appliance).

I buy my paint from a decorators merchant, but when I have a particular technical question about the product that goes beyond what a jobbing decorator might get to know from a decorators merchant, and what I need to know isn't available online, I go to the UK manufacturer/distributor's technical department. I am not over-bothered by who I hand my money over to, but I am very bothered about getting access to accurate and competent technical advice. This becomes even more important in a field like ASHPs where the technology is poorly understood, and the individual products all have their own complex and quirky setups and controls. The Midea technical manuals (the full ones) are often incomplete (eg the use of 'DIP swicth 6 to control output is implied rather than stated) and/or incomprehensible (eg abbreviations used with out explanation), and the average installer/merchant by definition will only know average stuff. That's why you need access to the technical department. Putting the installer/merchant as the man in the middle just complicates things unnecessarily. Of course businesses like Freedom like the B2B model, easy life for them, but it does nothing for good will.

Posted by: @cathoderay

I buy my paint from a decorators merchant, but when I have a particular technical question about the product that goes beyond what a jobbing decorator might get to know from a decorators merchant, and what I need to know isn't available online, I go to the UK manufacturer/distributor's technical department. I am not over-bothered by who I hand my money over to, but I am very bothered about getting access to accurate and competent technical advice. This becomes even more important in a field like ASHPs where the technology is poorly understood, and the individual products all have their own complex and quirky setups and controls. The Midea technical manuals (the full ones) are often incomplete (eg the use of 'DIP swicth 6 to control output is implied rather than stated) and/or incomprehensible (eg abbreviations used with out explanation), and the average installer/merchant by definition will only know average stuff. That's why you need access to the technical department. Putting the installer/merchant as the man in the middle just complicates things unnecessarily. Of course businesses like Freedom like the B2B model, easy life for them, but it does nothing for good will.

  

I agree totally.

Who sells you the kit is what is likely to be covered contractually. Who provides tech support is up for grabs. This is particularly important with things like heat pumps.

@HughF said earlier that he views ASHPs as appliances, and draws the analogy of purchasing from AO. But they're not just appliances. If you buy a fridge and plug it in you know what to expect and if it doesn't get cold then you take it back. If you buy an ASHP and wire it in, it's only one part of a much larger system to provide a solution and if your house doesn't get warm then the issue could be in so many different areas only some of which are related to the ASHP itself. AO have factored in the costs associated with customer support and faulty goods because it's easy to quantify. An ASHP manufacturer is in a different position, hence farming out the bulk of the problem to an installer network and putting itself in as a third line of support.

Like you, @cathoderay, even if I have to buy something complex from a distributor or retailer because of the sales model in place, I'd expect the manufacturer to provide all the technical details on request unless there's a VERY good reason to do so (e.g. only providing wiring diagrams to certified professionals to avoid amateurs blowing themselves up). If a manufacturer wasn't prepared to do that, that's definitely a fight I'd be prepared to wade into.

Posted by: @batalto

If you want to fit your own heat pump you are very much the exception to the rule. But the same would be true of most heating/plumbing work. Most people would rather get someone in because they don't see a heating system as a fridge (appliance).

I guess I’m in the minority as I do all my own plumbing, mechanic’ing, and construction work. 

My dad built our place from demolition materials in the 70s and we’re totally off grid there. He built the sewage plant, dug all the footings, did all the plumbing and electrics. Since then I’ve built and installed a new solar PV and lithium battery storage setup, plumbed in a new well, wired in new backup generators.

So you can probably see why I’m of the ‘buy it and fit it yourself’ camp.

My day job is software and embedded electronics for the offshore industry so setting a few parameters in an air source controller is a walk in the park 😂

Hi Hugh,

Have you considered an Air to Air heat pump, which can be purchased from Appliances Direct, and they also have a technical help department. I ordered a unit during the afternoon and it was delivered the following day. Cannot fault their service.

If you prefer an Air to Water heat pump then Google 'ASHP' which should reveal a number of units that it may be possible to purchase.

Posted by: @derek-m

Hi Hugh,

Have you considered an Air to Air heat pump, which can be purchased from Appliances Direct, and they also have a technical help department. I ordered a unit during the afternoon and it was delivered the following day. Cannot fault their service.

If you prefer an Air to Water heat pump then Google 'ASHP' which should reveal a number of units that it may be possible to purchase.

 

Indeed I have, but I don’t have F-gas, and my wife doesn’t want the warm air blowing around, and I want ufh in the new extension slab. So air-water it is, for now.

Believe me, I’ve spent three weeks pouring over spec sheets, price lists, user manuals, YouTube etc, I’ve narrowed it down to Cool Energy and possibly Acond. Was also looking a Sprsun, but can’t get any response from the UK agent, and taking to the factory in china, their MOQ is three units.

Some evidence that the Midea 14kW unit can't quite cope at low ambient temperatures...

I have finally got round to plotting hourly room temps vs outside ambient temps for February March and April this year. Most of the time, it was relatively mild, but there was a cold spell in early April, when the average ambient temp hovered around 2.5 to 3 degrees. During that cold spell, the room temp fell to average around 16.5 degrees, when the design temp for the room was 19 degrees. There was then a brief spell when the room temp exceeded 19 degrees, and then for the rest of the month it hovered around 18.5 degrees - see chart below.

The outside ambient temp wasn't the only thing that changed, which complicates interpretation a bit. The chart has boxes indicating changes that were made, the main one being switching from weather compensation to fixed LWT at 55 and then 50 degrees, see posts passim for why this was done. What the chart shows is that when the ambient temp is low (first few days of the month), and weather compensation is on, as recommended, the room fails to reach design temp by about 2.5 degrees. When the average ambient temp is over about 5 degrees, the heat pump can all but keep up (18.5 actual vs 19 degrees design).

Data: hourly room temp from an RC-4 DataLogger in my kitchen, hourly outside ambient temp from a nearby weather station (Alice Holt) downloaded from the Met Office's Weather Observations Website.

It’s not that the heatpump can’t keep up when weather comp is enabled, it’s that your curves are wrong and your rads are undersized for the flow temp that the curve has picked for that specific ambient air temp.

That’s why when you set a fixed flow temp the house was able to stay warm, the flow temp was higher than that chosen by the curve.

Higer temp = more heat output from the rads.

Posted by: @hughf

It’s not that the heatpump can’t keep up when weather comp is enabled, it’s that your curves are wrong and your rads are undersized for the flow temp that the curve has picked for that specific ambient air temp.

You may well be right, but I don't think I can be sure, because two things changed, but not quite at the same time: the outside temp and the heat pump settings. But if we look at the period when weather comp was on (1 to 8th April, meaning the only major variable changing was the outside temp), the shape of the room temp line pretty much mirrors the shape of the eye-balled average ambient temp line. Can't cope during cold spell 1-4th April, room warms up as outside temp warms up 5-6th April, and then cools down as it gets colder again outside 7-8th April.

The rads are sized to design temps at -2 outside, LWT 55 degrees (which is what the standard Midea curve that I had is set to at -2) 'plus a bit' as the rads have fixed sizes and the actual rad selected is the one that (a) fits available space, a major constraint in my house eg low ceilings and short walls means going for width rather than height and (b) has an output that exceeds the room's heat loss. Typically the 'plus a bit' is ~10 to 20% over the room's heat loss, a room with 1000W loss might have a 1100W or 1200W rad (at LWT of 55).

I thought the whole basis for weather comp was that there is an inverse linear relationship between heat loss and outside ambient temp, and the weather comp manages this varying demand by varying the LWT. This means the heat pump can operate in Steady Eddie mode, rather than fast and furious on/off mode. My old oil boiler managed increasing demand by firing more often and for longer, the heat pump does the same thing by raising the LWT. Conversely, when it is warmer outside the oil boiler fires less often and for less time, and the heat pump lowers the LWT.

For a room with a 1000W heat loss at 18 design, -2 ambient, it will have zero loss at 18 ambient, and 500W loss at 8 ambient. At this ambient, the heat pump lowers the LWT and the 1000W (at LWT 55) rad lowers its output (because the LWT is lower) to match or more accurately approximate the lower heat loss.

What this means in practice is that the nominal 14kW Midea unit can cope at higher ambients, but fails at lower ambients, when, crucially, its actual output falls way below the nominal 14kW to around 11.5kW (Midea's own figures, see posts passim). Given my house has a loss just over 12kW at -2 ambient, this means the unit will fail at these lower ambients. The house demands 12.4kW, but the heat pump can only produce 11.4kW, and so the design temp is not reached. I think the left hand side of the graph, when weather comp was on, shows this happening: lower ambients, cant cope, higher ambients, can cop.

The rest of the graph, when the design temp was reached, unfortunately can't tell us whether the design temp was reached because the LWT temp was set to a fixed 55 and then 50 degrees, or, as I believe is more likely, the heat demand fell, because the ambients were higher, and the heat pump output could meet the lower demand.

Until evidence emerges to the contrary, I am strongly inclined to think the limited evidence available in the graph shows that at warmer ambients the heat pump can cope, but at lower ambients, when crucially you most want to be warm, it can't cope. It's what the heat loss/heat pump/rad calcs predict (once we had the real Midea output figures, unfortunately only after the installation had gone ahead) and I think it is what we see.

All this only happens and only matters when it is cold outside. Maybe with global warming it'll stop being cold outside. More realistically, I will have to wait until next winter, and see what happens in cold spells. I rather suspect the can't cope threshold is around 4 to 5 degrees average ambient, which just happens to coincide with when defrost cycles kick in, further lowering the heat pumps output. If next winter's data show this to be the case, then it will be time to test the dip switch option to raise the Midea's output from 14 to 16kW. In theory (ie in the calcs), my system is set up to reach design temps at -2 ambient, LWT 55 (the standard Midea curve LWT at this ambient). If it fails, I don't think it is because the rads are too small (the calcs show they aren't), it is either because the weather comp curve of and by itself doesn't deliver the right LWT predicted by the curve, or, more likely, it can't get the LWT up to temp because the heat pump output is inadequate, 11.5kW output is less than the 12.4kW demand.

PS I don't have hourly LWT readings, because that frigging Midea app became just too much hassle to use, and even if I had got it working, then I am not sure it would show hourly LWTs as recorded by the pump unit sensors, which may or may not be accurate. Spot checks on the Midea controller generally showed it was all over the place. However, I did use an IR thermometer on the primary flow into the heat exchanger (with black insulating tape on the copper to get about the right emissivity), where the temp would be less than the LWT because of losses from the pipe between the pump and the heat exchanger but by how much, and got twice daily (0800/200) readings in early April during the time when the design temp was not reached which averaged 45 degrees (range 38 to 52). But the problem in interpreting these numbers is constantly changing variables: as the ambient goes up and down, so the weather comp changes the LWT. Is 45 degrees average, range 38 to 52 as it should be, or wrong (loo low)? That is why I prefer to use a single understandable and relatively stable measurement that also happens to be the one that matters, the room temp. To use quasi-systems analysis language, the LWT is a process variable, but the room temp is the more important outcome variable.                 

@cathoderay Ah, I didn't realise you had such high heat loss and your machine was undersized. That's unfortunate. Who specified the unit?

Posted by: @hughf

Ah, I didn't realise you had such high heat loss and your machine was undersized. That's unfortunate. Who specified the unit?

It's a long story, spread out over many months, and covered in some detail in earlier posts in this thread. In summary, it was specified by my installer (who I am happy with, despite the outcome, as I believe he was acting in good faith), who in turn relied on Freedom Heat Pumps heat pump calculator, which in turn had the wrong output for the 14kW unit at lower ambients. To be fair, the calculator had a note saying the outputs for the unit were estimates, but at the time of specification, they were the only outputs we had, and so had to rely on them. It was only after the installation that the true Midea data came to light, thanks to this forum and its very knowledgeable and helpful contributors.

There is a further twist in that originally a 16kW unit was specified, but when it came to installation time only a 14kW was available, and time was of the essence, because of a combination of my installers availability plus the grant deadlines, meaning we couldn't wait months for a 16kW unit to become available. It was 14kW or nothing (and back to oil fired heating, because it had to be a low profile Midea unit for planning/listed building reasons). We knew the 16kW unit was definitely adequate, and had a margin, but the 14kW appeared (on the basis of the Freedom spreadsheet) to be just adequate (101% of demand supplied), and so we went with it, for the reasons given. We now know it was inadequate, on the basis of Midea's own data.

An even further twist is that it turns out that the Midea 12, 14 and 16kW units are almost certainly the same on the inside, and there output is simply set by three dip switches. Apparently manufacturers do this sort of thing, build the same boxes for economies of scale, and them set them to be different models to make it look as though they have an impressive range, and furthermore sell the 'higher rated' boxes for more money. This means there may be a simple solution, flicking a few dip switches, but I needed to be sure the unit was inadequate in practice, and that meant (and still means) waiting for cold weather, because only then would the inadequacy appear. I also need to clear changing the output with my installer (who I have no doubt will be happy with the change) and more importantly Freedom, because they provide the warranty. But most importantly, I only need to make the change if the unit is inadequate, and that means waiting until next winter and a cold spell, when it should become clear whether the unit is adequate, or, more likely, inadequate.

The high heat loss is typical of an old leaky listed building. Options for improving thermal efficiency are limited. I took the view that if we are serious about moving to semi-renewables or even faux-renewables (how is the electricity that powers my heat pump really generated?) then we need to start installing heat pumps in homes that are not ideal heat pump homes, but nonetheless account for a large part of the UK housing stock (not the listed bit, but the old and leaky bit), and see how things work out. As things stand, the government could not be further from its aspirational 600,000 heat pump installations a year for the next few years. The only way that can change is if we get on and go ahead and install the things. The appalling management of the now inadequate grant schemes doesn't help either, and take up of earlier schemes has been shockingly low, see this earlier post of mine.