Posted by: @derek-m

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I think that you may need to ask Freedom to clarify exactly what they mean

It is typical Freedom obfuckstration, balderdash and confusion. It's obvious that LLHs, buffers and PHEs are not the same thing when it comes to hydraulic separation. As you say, only a PHE truly does that. As I said elsewhere, the best you can hope for from Freedoms's 'engineers' when asking technical questions is the answer to how does it take to get to Tipperary (clue: answer is it's a long long way). And anyway, they don't talk to punters like me. 

@mike-h The short cycling problem is improved but not resolved. It seemed like it was the thermostat constantly switching it on and off so I dropped the upper flow temp to 42 then set the thermostat to 23. This causes the heat pump to constantly try to reach that temp but can't - so it stays on. Not an ideal solution but it works in the evenings while the wife is home. During the day and at night when the stat is set lower it still goes on and off.

@hughf I actually wanted a TADO but its not compatible with the Samsung. The Samsung controller is in the kitchen next to the hot water tank, why do you ask?

Posted by: @riponowl

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@hughf I actually wanted a TADO but its not compatible with the Samsung. The Samsung controller is in the kitchen next to the hot water tank, why do you ask?

A TADO in on/off mode is equally compatible with the Samsung as the Hive. I ask where the Samsung controller is located as that can be used as the room ‘thermostat’, and is the obvious choice for this task. It can adjust the flow temperature down when the room reaches the set point, instead of just turning the heat pump off. It might also be able to revert to load compensation to recover quickly from a setback temperature.

You’d typically only use a normal room stat when you’ve got the heat generator and the heat user separated by a buffer or llh, with a secondary pump being driven off the room stat. It’s the worst way to plumb these up. 

@hughf Thanks for that. If its true that the Gen 6 Samsung controller reduces the flow temp when it reaches the set temperature then that's exactly what I need. I have no problem dropping the Hive if need be. It raises a few more questions though.

1. As the Samsung controller is currently stuck on my hot water tank it will need to be moved elsewhere and the cable is short. Can it be used wirelessly?

2. Is 'disconnecting' the Hive as simple as changing a setting on the Samsung controller to say its not using an external thermostat?

3. Does the Samsung have the ability to set a temperature schedule for different times of the day? I need it to be hotter in the evening (when the wife is home). At the moment I can't nosey around in that menu as it locks you out if you have an external thermostat set up.

If anyone has answers to be the above I would be very grateful.

One last thing, I did speak to the TADO support team at the time and they said that the TADO is not compatible with the Samsung MIM-03 controller.

@cathoderay, who installed your system?

Posted by: @riponowl

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@hughf Thanks for that. If its true that the Gen 6 Samsung controller reduces the flow temp when it reaches the set temperature then that's exactly what I need. I have no problem dropping the Hive if need be. It raises a few more questions though.

1. As the Samsung controller is currently stuck on my hot water tank it will need to be moved elsewhere and the cable is short. Can it be used wirelessly?

2. Is 'disconnecting' the Hive as simple as changing a setting on the Samsung controller to say its not using an external thermostat?

3. Does the Samsung have the ability to set a temperature schedule for different times of the day? I need it to be hotter in the evening (when the wife is home). At the moment I can't nosey around in that menu as it locks you out if you have an external thermostat set up.

If anyone has answers to be the above I would be very grateful.

One last thing, I did speak to the TADO support team at the time and they said that the TADO is not compatible with the Samsung MIM-03 controller.

Attached is the samsung gen6 manual as supplied by midsummer wholesale. Their installation instruction and wiring is more advanced than that from Joule/Freedom in that they talk about the primary pump being PWM (speed) controlled and show the settings needed to run the samsung controller as the room stat.

The freedom samsung gen6 videos that are floating around on youtube make passing mention of the PWM wiring to the pump but GH says in the video 'we played with this, it didn't work so ignore this wire'.

You'll need to remove the samsung controller from the front of the tank in the airing cupboard and fit it nicely somewhere downstairs. You can use the two core cable that's currently running the hive to connect the controller back to main PCB.

Yes, I'm pretty sure the gen6 controller will have a scheduling capability.

I should add, I'm an electronics engineer and this stuff doesn't phase me. If you're not technical and aren't happy working in and around your house electrics then please find someone who is.

@editor - a local firm, I've been at pains not to drop him in it because he has been very helpful throughout (I would recommend him), though I think at times he might have been a bit out of his depth. He's not new to heat pumps, but does a standard by the book Freedom installation, which is why I tend to point my finger in their direction, my installer was just following their instructions. His sub-contracted plumber is mainly a gas plumber, and not that clued up on the finer points of ASHP systems eg the PHE being piped up with non-contraflow.

Apart from obviously needing a new heating system given my oil system was on the way out (after 25 years or more of use), and Argos type heaters had shown themselves to be expensive to run and not effective enough, and not wishing to spend ££££ on a fossil fuel system that in a few years time might look like something of a dinosaur, my main driver for going with an ASHP was to see whether one can work in an old leaky building. I think this matters, because a lot of our housing stock is old and leaky, maybe not as old and leaky as mine, but still not text book ASHP homes. If anyone is serious about installing a lot of ASHPs, then they have got to be made to work, and shown to work, in these less than ideal properties. My property is also listed, and that was another hurdle, no permitted developments for ASHP for listed buildings, so needed both planning permission and listed building consent. The later was a major factor is the choice of heat pump, most >10kW units are tall and narrow, but Midea's are short and wide, making them less visually intrusive.   

I did my research, and on paper there was no reason why an ASHP shouldn't work in an old building, but there would need to be compromises, eg higher end LWTs, and an acceptance that old leaky buildings are always going to lose more heat, and so will be more expensive to heat. But that applies whatever the fuel/system is in use. One possible positive which I hadn't spotted in advance is that, although the house takes a long time to warm up from cold, once it is up to temperature, the fabric acts as a huge heat sink/store, and that helps level out the temperature (most of the time, there have been some exceptions).

One thing I learned very early on in the process is that there are a lot of chancers and cowboys out there. I did my own heat loss calcs when I fitted central heating using a solid fuel boiler almost 40 years ago, and they got updated when I had an extension done (just before the building got listed!), so I know the basic principles, and it was obvious not all ASHP installers do proper calculations. There was also a huge variation in potential design solutions, from 'it can't be done' to over-complicated (and expensive) solutions to obviously inadequate solutions that used the old rads and an undersized heat pump. The installer I chose, as well as being helpful and accessible, was roughly in the middle, definitely not an outlier. I also had a prolonged and increasingly unpleasant experience with a LAD grant preferred installer which end up with me saying I would not let them within 10 miles of my property on pain of being shot on sight, and going back to my preferred installer.

It's still early days, and that matters because by and large my system has only been running in mild ambient temperatures, and I don't yet really have a proper feel for running costs, but from a heating and hot water point of view most of the time it is fine. The necessary caveats are I don't know whether it will be fine in colder weather (on paper it is borderline), and it does have periods of a few days up to a week when it just decides to run colder, maybe with rooms about 3 degrees below design temps. This has happened twice, once in the spring, probably linked to cold weather at the beginning of April, and once at the beginning of November, with no obvious explanation except possibly it was immediately after a period in which I was balancing the rads, maybe the Midea controller got confused. It wasn't the balancing itself, I went from valves fully open to closing them as needed to get rad temps and more importantly room temps balanced. I may also be in for a nasty kWh usage shock if when we get cold weather, I just don't know yet.

Sorry, rather a long answer to a simple question which I seem not to have answered!         

@cathoderay 

Similar to our install, 1946 block/block construction with a 2" cavity, that has been blown. Double glazing, suspended timber floors and a chimney running up the middle (that if I had my way, would be removed and sealed up)... Old and leaky but typical of a lot of building stock.

Freedom toolkit gave us 6.6kW at -3 outside, heatpunk software gave us 4.8kW at -1.5 outside... A bit more rad sizing to do and I'll be cracking on next spring.

@hughf - mine's a bit older, mid 1700s with later additions. All solid stone walls with the exception of the extension I added. Single glazed with a mixture of frames, some old oak, some cast iron (unusual and attractive) and some galvanised, all of which which I am going round adding secondary glazing. The work is not straightforward, many of the frames are not square, and lack a flat landing surface of the magnetic strips. Draughts almost everywhere. My calculations and Freedom's calculator came out very similar, where the Freedom calculator got it wrong was on the Midea outputs, over-optimistic given what we now know. The other big factor I had to deal with is lack of wall space and solid floors, which significantly limited available space/options for where to put the rads. I ended up with mostly K3's, the visual bulk, they are not pretty, somewhat reduced by surrounding furniture which sticks out more than the rads. I have virtually no free wall space at radiator height in any room.

Many of the houses I can see from my windows are just like mine, small old stone cottages. They will all have exactly the same problems as I have had when they try to fit ASHPs. Many will be told by those who should know better there is no way an ASHP will work in their homes. As I said above, they can work, with compromises, and realistic expectations about energy usage, given old leaky buildings all other things being equal will always use more energy. 

I know you will know this, but others may not, if you have the choice, always go for the higher output rads. It gives you more options for running at lower LWTs. The constraints I had, limits to the practical size of rads that could be fitted, meant the system had to be designed to run at a high-ish LWT, with the efficiency penalties that entails. It is a heating system, and it just as important that the rads can deliver the heat to the room, as it is that the heat pump and circuitry can deliver the heat to the rads.   

@cathoderay I've modified Freedoms calculator (tweaked the w/m2 value) to size my rads for a 45 degree flow temp and I'm shooting for 35% oversize in the two lounges which are the hardest rooms to heat with the current rads.

At the moment it looks like I can get a job lot of 600x1200 type 22's and stuff one of those in every room and 2 in the north facing lounge.

@hughf - I didn't use the Freedom w/m2 values, 500W x 1000H is not the same output as 1000W x 500H, its a typical Freedom fudge. Better to use the 'conversion factor' ie how much to downrate the output depending on flow temp/delta T. Very roughly, ASHP systems need rads ~ x2 compared to fossil fuel systems. Suppers on the boil, unlike my rads, will explain more if needed tomorrow.