MelCloud readings

DavidAlgarve · 2024-10-15T08:34:46Z

I don't rely on MelCloud for control of my ASHP, but recent discussion on another topic regarding the application, has prompted me to look again at something I didn't pursue earlier. I have no inside thermostat/ thermocouple, but my MelCloud gives a reading for "Room Temperature" (currently 23.5C) and I can't understand where that figure is being sensed. There is a Mitsu Air Conditioner, but I doubt there would be interaction between the two systems. The Ecodan is in an outside pump room with much lower temperatures so it is unlikely to be from there. There is also the facility on the app to "Set Temperature" but this has no apparent effect. Prior to winter I am refining my weather compensation curve, but wonder if these features are of any value to me. I would appreciate advice on how I might determine where this data is being sensed and if it and the variable "Set Temperature" can be used to advantage.

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Air Source Heat Pumps (ASHPs)

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SUNandAIR

(@sunandair)

Noble Member Member

Joined: 3 years ago

Posts: 542

18/10/2024 7:45 pm

Hi @davidalgarve

It’s interesting to hear your thoughts on the wireless remote and why it might be confusing for others.

I hope you can see from the picture that the only information on display is an adjustable target temp and an actual room temp.

It has up and down buttons to raise or lower the target temperature plus a “tap” button to override heating at any time to heat the domestic hot water whenever it’s needed.

At face value that might be all you need to operate in weather compensation. But you also have the benefit of having the room temperature on display. And you can always boost the DHW at the press of a button.

If you’re still tweaking your weather compensation downstairs in the plant room the wireless controller would give you simplified controls just for the living space.

In Auto Adaptive mode the wireless unit becomes a smart controller in that the target temperature provides feedback to the FTC to modulate the heat pump as the temperature is approaching the target or to boost the heating if the target is much lower than the target temperature.

Regarding your thermistor TH2 I’ve not encountered that thermistor so not sure what it relates to….

hope Thats useful

This post was modified 1 year ago 2 times by SUNandAIR

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Abernyte

(@abernyte)

Honorable Member Member

Joined: 3 years ago

Posts: 254

19/10/2024 11:54 am

From my experience of using the Mitsi wireless controller in auto adapt mode since 2019 it is the ultimate in fit and forget. It sits in the centre of the house and with my programmed MelCloud schedules providing the target temps at the appropriate time it just gets on with it without any intervention and the house is uniformly heated at the energy use predicted by the heat loss survey. It usually overshoots the target temp by 1 degree C and then stops heating and just circulates fluid until there is a change of state. OAT rises and IAT stable or rising system goes off, OAT falling it monitors the IAT and eventually comes back in.

It really couldn't be easier.

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DavidAlgarve

(@davidalgarve)

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Joined: 2 years ago

Posts: 217

Topic starter 19/10/2024 2:01 pm

Two keen users and I will reconsider, but what I was anticipating was conflict between what I had carefully arrived at on the FTC5 and what someone else (my wife?) might do on the wireless unit, without necessarily understanding. It sounds as though auto adapt avoids that.

It is academic I suppose, but I am still perplexed about where the "Room Temperature" on the app comes from and it does not appear to come from TH1 as has previously been suggested, because e.g. as I write the app is telling me "Room Temperature" is 21C and both TH1 and TH2 are reading 23C.

I am convinced that there is no thermocouple in the FTC5 as there are just two wires (Data?). In the Ecodan cabinet there are just 3 thermocouples, with 1 each on secondary flow pipes and a third on one of the primary pipes from the outside unit. To confuse matters further there is nothing plugged into connection point CN20 which, according to the manual, is designated as "Room Temp"

Could be the third thermocouple I identified above be the one referred to in the manual as "Ref liquid temp" as that is plugged into CN21?

This post was modified 1 year ago 2 times by DavidAlgarve

342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW

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