roadrunnerAlgarve

I can confirm that if I change "Set tank Temperature" on the MelCloud app it changes the DHW water temperature setting on the FTC5 With setting at 40C, the FTC5 shows a DHW temperature of 41C whilst the thermometer shows 44C. However, the probe is at 1/3 tank height and the themometer is at 2/3 height. So one question resolved, but now need to find out where the heating system is getting it's room temperature reading!

No the buffer tank is not Mitsubishi, but I think there must be an operative thermostat in this tank, because when the system was first installed and the FTC 5 was set on 50C , the buffer tank was at the same temperature. I have just bumped up the setting on the app to 50C and will see what temperature is shown on the FTC5 DHW setting and the DHW tank tomorrow.

I have a Mitsubishi Heat pump connected to a radiator system via a buffer tank. I also have a DHW tank connected to the heat pump. On the MelCloud app, there is a provision to "Set tank Temperature" Is this the buffer tank or the DHW tank? It doesn't seem to match either in my case E.G Set temp 45C and buffer tank is 34C and DHW tank is 42C If it is DHW tank and I change setting on MelCloud, does it adjust setting on FTC5?

Sorry to show my ignorance again on Weather Compensation. If I enter the weather compensation 1st screen there are two options with the LHS being presumably for "View" and the RHS for "Edit" However if you select "View" there is a provision for adjustment of the lower temperature with horizontal arrows. What is the purpose of this adjustment? The settings bear no resemblance to those achieved by adjusting the High and Low settings from the "Edit" screen

Thanks Sliderule. The FTC control box is located in the front panel of the Hydrobox and this is mounted in my pump room so will be at near ambient temperature. Ambient temperatures have been significantly below the "Room Temperature" read out so that doesn't seem to fit. The main living room has two rads, each with TRVs, but these are combined into one Tado thermostat which controls the TRV position and this is not connected to the heat pump.

Thanks Sharpener, but I don't know if there is an outdoor temperature sensor. The FTC5 is mounted in my pump room which will be at ambient so a sensor inside the panel would give reasonable results.

Night temperatures are going down so I am trying Weather Compensation, but not promising results so far. I have looked at YouTube videos but the display and available controls on my unit are not the same and I can only change the lower temperature and most times it returns to -32! Photo attached. What am I doing wrong, please?

You have reminded me that there was an additional WiFi relay device that switched the boiler according to chosen timer settings. So the Tados only had a function when the timer setting was "On" and the boiler running. That unit was discarded when the boiler was scrapped. What I would like to find out is where the displayed room temperature comes from, when there is no Mitso room thermometer!

It very rarely gets below -2C /-3C now and even that doesn't last long. When we came to live here 18 years ago, it would get to -5C and for longer periods. The Tado TRV's are only controlled from the Tado app. Most of the rads are individually controlled but the lounge has two rads and these are combined on one Tado room thermostat. In view of the spurious Mitsubishi room temperature it would be good to feed in this signal to the heat pump, but I wouldn't think that is a goer. There is only my wife and I in the house with the lounge and 3 bedrooms on the upper floor. These 3 bedrooms very infrequently used when family, living elsewhere in Europe, visit us (normally in summer!). Downstairs is the master bedroom and a family room/ office. In the colder periods we have lounge and kitchen at say 22-23C in the evening and 19C in the day. Upstairs bedrooms are at 19C. Downstairs bedroom is at 19C during the day and 22C in the late evening. The Tado TRV's were brilliant with the old gas boiler and I cannot imagine how I could achieve the same results without them.

Yes it is the Algarve. I only came to the conclusion that the original contractor was bad when it was too late and that is why I chose not to use him again. However, my main mistake was in choosing Mitsubishi, because the support and I suspect, knowledge is non existent. I suspect the rads will suffice as they are the rather large cast aluminium ones and not the pressed steel ones used frequently in UK. They are all on one circuit, upstairs and downstairs and I want different temperatures in some rooms, hence the Tado TRV's. What I am wanting to do is optimise what I have, but it sounds as though I will have to wait until colder weather before I can get any meaningful results.

A small addition to the above. The House heating is now set on "Compensation Curve" and the buffer tank thermometer (about 15cm from top of tank), was reading 32C before heat pump started at 18:00 and it is now 34C and the heat pump has stopped running. Only a small demand (3 towel rails) Outside temperature is 18C. What is switching the heat pump?

Thank you very much for all the responses. However, it makes me realise that I just took so much for granted with the contractor that insalled the ASHP. For example, as I recall, the system was left with what is now clear, was a 55C target flow temperature and I (wrongly) understood that the buffer tank was being controlled at that temperature. Consequently the radiators were heated at 55C as opposed to the circa 65-70C from the old gas boiler. There was no Mitso room thermostat and the Tado Smart TRV's seemed to do a good job in controlling individual room temperatures. I feel rather sceptical that I will get sufficient heat with a radiator flow temperature of 35to 40 although I recognise that using compensation may deal with this. Equally, I can't see how a Mitso remote controller can work with the multiple Tado Smart TRV's other than setting it at a higher temperature than I would ever need in e.g. the lounge. I would appreciate comments on the above before posting separately on DHW, but I would just make it clear that I recognise the need for timing DHW heat input at a different time to space heating. At the moment, I have DHW heating times of 04:30 to 6:00 and 14:30 to 17:30 and will see how that works

I have a Mitsubishi ASHP (PUHZ-SW120YHA) plus Hydrobox (EHSC-VM20UK) installed by one contractor and a DHW tank installed by another, at a later date. The DHW tank was completed in June and foolishly, I did not check both heating and DHW working together. I do not have a Mitsubishi room thermostat, but have Tado Smart thermostats on almost all radiators. I am including a photo of the FTC5 panel. I hope that the small tank temperature icon to the right of the tap, is reading the DHW tank temperature, although there is a small difference to the actual tank thermometer reading. What I am uncertain about is the “Target temperature” setting. Before installation of the DHW tank this was set at 55C and it maintained the buffer tank at this set temperature This target temperature has three options: Target Flow; Target Room and Compensation Curve, I.e. Which of these settings must I select to control the temperature in the buffer tank? (“Target Flow” seems to be the only one that allows me to set a temperature of, say 55C) The Mel Cloud app confuses things further by showing a set “Set temperature” of 22C and a “Room temperature” of 24C. How can the system possibly know the room temperature with out a Mitsubishi room 'stat? If I try to increase this setting, it just changes it to some figure around the 22C