I don’t have any of these problems. ?

but I don’t have a Tado either

Welcome, ecodan- prisonar. You raise so many points that I don't think I can attempt to answer all in one post, but I hope that answers will unfold from others in future posts. I will just comment on three.

I do agree that the MElCloud app is a disappointment for a heat pump and it is beyond me why it can't be as good as it is for air conditioning units. If others agree on this, perhaps we could put some pressure on Mitsubishi?

Regarding Tado, I am not sure I understand you, because I still have Tado working with their app and it is no problem.

However, as I have learned from others on this forum, with an ASHP you should not use them as you used them with a boiler, but they should be set them just beyond what you want the room temperature to be (to deal with e.g. any solar gain etc.) and let the ASHP control the internal temperature. My installer set my heat pump at a fixed 50C and with timer settings (just like a boiler!) and it was very expensive for the first winter. On advice received here, I changed over to Weather Compensation and it transformed the performance. The Tado's are still there clipping temperatures in some rooms that are underused, or subject to a lot of sunlight.

Noise - I don't understand this at all, because my big unit makes less noise than the boiler used to make at say, 2m!

Posted by: @ecodan-efficiency

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Warning for anyone considering Mitsubishi - their melcloud app and internet enabled ASHP control is terrible and hasn't been updated in the two years I've had the system.

It would be nice if one could perform such basic actions as changing the heating mode (Inhibit-Schedule-On) via the app. But no. Not such luxuries are available.

Imagine a world where you could have more than one preset schedules stored in the controller, and were able to switch between them (maybe even via the app!). Alas, you get one.

Good luck figuring out how to use (the melcloud only!) "Frost Protection", given that you can set it to kick in at 4 degrees or so when the minimum temp the system itself can go down to is 10 degrees. If the system was on a schedule and inhibited, would the Frost Protection override this? Who knows, it's up to the poor end user to try and fathom this nonsense out. Any why is there a hard minimum of 10 anyway?

How about the manual explains in simple English what exactly "Holiday mode" does.

Why can't I use Tado!?

Sorry for the rant. Outside of these primarily usability issues, the system performs well enough. However I've already decided to move as the incessant noise from the pumps as it struggles to counter the excessive heat loss in my ex-local authority house in Scotland is driving me insane!

As @davidalgarve has said, there's a lot going on in your post. I won't say you're wrong since if a particular heat pump doesn't suit you then it doesn't suit you. However, that doesn't mean all the issues you're facing are down to the heat pump.

Firstly, Melcloud. Yes, it's rather limited and both the app and the web portal only provide a subset of controls for the heat pump when they could offer more. No disagreement here. That said, general received wisdom these days is to set the heating system to do what you want and then leave it alone, meaning the availability in your pocket of access to every detail of its configuration becomes far less important.

That same received wisdom suggests you use the heat pump to control the heat pump. Tado, for all that it's a smart control, is still just a thermostat and that's not the most efficient or effective way of running a heat pump; that's a bit like keeping your car at full throttle and controlling the speed with the brake. Far better to let the heat pump moderate the amount of thermal energy being injected into the heating circuit than to keep it running at full chat and have a thermostat periodically turning it on or off.

Even then, I wonder how well things would work anyway if you're using one smart control to tweak the heat pump and another separate one to tweak the house temperature. My guess is that they'll want to fight each other rather than play nicely.

If you want to gain access remotely to all the functionality the Ecodan is capable of, there are options. One, of course, is to get an optional modbus interface fitted and to connect the heat pump up to a home automation system (Home Assistant, Homely etc.). Each is its own set of compromises but at least all of them involve controlling both the heat pump and the house as one cohesive solution instead of separate apps that don't know about each other.

Finally, let's not forget that the heat pump only injects heat. If you were running a gas boiler efficiently (low flow temperature, weather compensation etc.), those pumps of yours will still need to work just as hard to move the water around the system and therefore produce just as much noise. It's just that it's easier to whack the flow temperature up high with a gas boiler so that less water needs to be moved to inject the same amount of heating energy into the house, but easier still doesn't mean efficient.

It seems pretty obvious you've got into a situation where you're frustrated, and that's not really conducive to an open mind. Nonetheless, if you are still able to keep your mind open there are alternative setups that, with a bit if discussion with you, could be fleshed out and that might remove your issues in ways you might not expect.

@davidalgarve Hi, the noise I'm referring to is the noise coming from water pumps that are located near the cylinder. The outdoor unit is not an issue. I've decided to get a plumber in to determine whether this noise level is "normal". For all I know a pump could be faulty. However I am forced to run the ASHP effectively like a gas boiler ie room temperature mode, because the incessant noise would drive me crazy otherwise. And despite what people say on these forums I remain to be convinced that it would work out cheaper, given the small amount of experimentation I've done in the past.

@majordennisbloodnok Hi, I have a genuine use case that is causing me frustration where the property will only be periodically occupied in winter. Saying that I should set it and forget about it is not helpful in my case. As described above, I use the system more like a traditional boiler, which means Tado would in theory be adequate. I am aware of "Holiday Mode" - however it is opaque, I don't trust its operation, and is too awkward to use - especially for a 3rd party.

I agree if one were running the unit in the much lauded, although too complicated for mass adoption, flow temp/compensation mode then Tado as it currently stands is not an option (I've not spent time investigating where Tado are at with more sophisticated ASHP specific controls since having the unit permanently on is a complete non-starter for me personally). The idea that I would waste money and countless hours researching modbus/home assistant just to be able to remotely toggle the heating mode and have more than one preset schedule is, I'm sorry, questionable at best.

Posted by: @ecodan-efficiency

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It would be nice if one could perform such basic actions as changing the heating mode (Inhibit-Schedule-On) via the app. But no. Not such luxuries are available.

Imagine a world where you could have more than one preset schedules stored in the controller, and were able to switch between them (maybe even via the app!). Alas, you get one.

The app whilst clunky can do a lot of things, there are 3 quick presets for room temps but if you aren't using the heat pump controller to control the temp then it will never work.

There is a timer function in the app that you can tell the heat pump to come on by hour, by day of the week and date of the year and whether to use a fixed temp or weather compensation curve for heating or whether to heat the water.

Posted by: @ecodan-efficiency

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Posted by: @ecodan-efficiency

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Good luck figuring out how to use (the melcloud only!) "Frost Protection", given that you can set it to kick in at 4 degrees or so when the minimum temp the system itself can go down to is 10 degrees. If the system was on a schedule and inhibited, would the Frost Protection override this? Who knows, it's up to the poor end user to try and fathom this nonsense out. Any why is there a hard minimum of 10 anyway?

I'm not sure what you mean by the system only goes down to 10 degrees?  Frost protection will overide a schedule that's the whole point of it, if its not heating and it gets too cold it starts heating to prevent water freezing in the pipes and bursting.  Its also not melcloud only there is frost protection in the main controller that turns on the pumps to cycle water through the unit and the house so it doesn't freeze the temperature that this comes on can be altered or it can be disabled completely if you have antifreeze in the system.

 

Posted by: @ecodan-efficiency

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How about the manual explains in simple English what exactly "Holiday mode" does

Holiday mode just overrides your schedules whilst you are away, apart from frost protection, tell it how many days you are away and it will turn back on when you return.

 

@gary Hi, I realise that there are three preset room temps on the melcloud app. I specifically said preset schedules.

I mean the lowest room temp on the controller is 10 degrees. "Frost Protection" on the melcloud app is not the same as the "Frost Stat" function that is found in the service menu, as I understand. The former is heating related and will bring the room temps up to the set temperature while the latter is about circulating a smaller circuit of water through the heat pump. Someone can correct me if I'm wrong but I don't recall the radiators being warm when "Frost Stat" is active.

It's not clear to me the benefit of "Holiday Mode" vs just turning off the schedule and reducing the room temp. I've also heard about it heating the hot water up while turned on whereas I would expect it to turn off DHW, I guess.

Posted by: @ecodan-efficiency

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However I've already decided to move as the incessant noise from the pumps as it struggles to counter the excessive heat loss in my ex-local authority house in Scotland is driving me insane!

If you have made your decision to change, then there is not much more that we can offer, but I feel certain it would be of interest to our contributors to know a little more about your set up so that we can advise others. (I would certainly be interested!)

In particular, it would be interesting to know if you are operating at a fixed temperature and using the Tado's to control individual heat emitters and what these are, i.e. radiators; under floor etc. or are you using weather compensation 

Posted by: @ecodan-efficiency

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However I've already decided to move as the incessant noise from the pumps as it struggles to counter the excessive heat loss in my ex-local authority house in Scotland is driving me insane!

If you have made your decision to change, then there is not much more that we can offer, but I feel certain it would be of interest to our contributors to know a little more about your set up so that we can advise others. (I would certainly be interested!)

In particular, it would be interesting to know if you are operating at a fixed temperature and using the Tado's to control individual heat emitters and what these are, i.e. radiators; under floor etc. or are you using weather compensation 

@ecodan-prisoner

Posted by: @ecodan-efficiency

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I specifically said preset schedules.

This is why I mentioned the timer function in the app you can set anything you like by the minute every day of the year.  Is there something specific that you are trying to achieve? As you have a third party thermostat controlling the room temperature you won't be able to control that through the app, but you can tell the heat pump when to come on or not in the schedule.

Posted by: @ecodan-efficiency

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I mean the lowest room temp on the controller is 10 degrees. "Frost Protection" on the melcloud app is not the same as the "Frost Stat" function that is found in the service menu, as I understand

Frost protection in the app is to protect the building from freezing you set the minimum that you want the heating to come on at and the maximum you want it to heat up to, is there something you are trying to achieve here?  Its used for when you are away for long periods and you have the heating off.  Its unrelated to the level you can set the internal temperature on the controller to as this is when you are in heating mode and why would you want to set a level of heating lower than 10C.  In your case you aren't using the main controller to control the house temperature so that is irrelevant anyway, but it will use the main controllers temperature sensor for frost protection mode.

Frost stat is to protect the heat pump and you are correct it just circulates the water in the system to stop it freezing it does not heat the water.

The benefit of holiday mode is that you don't have to remember to turn it back on but other than that its the same as turning off the unit.

@davidalgarve Hi, sorry if I wasn't clear - I don't currently use Tado for anything. I had thought it might have been an alternative to using melcloud. (I realise Tado would only control the heat pump in a basic fashion). It's just a conventional over-sized radiator setup.

@gary Hi Gary, have you actually used Frost Protection and verified that behaviour? I was told by the official Ecodan support that Frost Protection will not do anything if the heating is "Off". (it wasn't more clearly explained to me than that and I've not experimented yet) In terms of trying to achieve something, it is to leave the property for extended periods at less than 10 degrees (say six or seven for arguments sake) and remotely warm it up before returning. My current option would be to use a schedule and once a day warm to 10 degrees say, however I can't then get out of that mode while not in the house and it means wiping the schedule I would normally use while in the house.