@f1p Thanks for your interest. Yes it is set for Room RC1. I am going to move the Par 60 from the second coldest room in the house to an upstairs bedroom, currently registering 21C on a Shelly Gen 3, and see what happens.

I am ordering a connector to be brought out to me later in the month.

The default for an unpaired or incorrectly assigned thermostat is also 20, could you further check:

Initial settings > Room sensor settings > Room RC zone select > Room RC 1 = Zone1 (black background)

@f1p1p I have checked both and believe them to be correct, (see photos), but I would appreciate your confirmation.

I now think this was a false trail because moving the PAR 60 to a warmer room resulted in an "Inside Temperature" readout of 21- 21.5 C

Weather compensation is now 27C @ 18C, but at +8, in an attempt to get an increase in inside temperatures. For the first time in 3 years we are getting signs of mould in the North facing rooms.

I have ordered a connector but I won't get delivery for about 3 weeks.

The only thing that I can think of trying now is the dip switch for Mixing (Buffer?) tank.

@davidalgarve 

The settings look correct, and i see you now have movement in the value - so it appears to be working.

I know there is some filtering, but is it accurate or is there a difference with other sensors?

@f1p

Right now it is sitting next to Shelly Gen3 in the living room. The PAR 60 is reading 21.5 and the Shelly is reading 21.8

The detailed report is here:

https://melpump.com/public-report/view/019c1e2a-6844-7aeb-9f9a-f0f6270fe56e

Thank you for your continuing support.

P.S. I have just received confirmation from Mitsubishi UK that my PUHZ-SW 120YHA is 12 Kw and not 16kW so will change it on the app.

The DeltaT is pretty high, by the sounds of it flow rate too low for the outdoor unit size
Pump might be set on 5 - but potentially it needs replaced with a larger circ pump

It's quite impressive you are pushing 44C flow at a freq of 26Hz

Posted by: @f1p

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The DeltaT is pretty high, by the sounds of it flow rate too low for the outdoor unit size
Pump might be set on 5 - but potentially it needs replaced with a larger circ pump

Or the filters cleaned ...   OP says upthread that he hasn't checked them!

Posted by: @jamespa

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Posted by: @f1p

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The DeltaT is pretty high, by the sounds of it flow rate too low for the outdoor unit size
Pump might be set on 5 - but potentially it needs replaced with a larger circ pump

Or the filters cleaned ...   OP says upthread that he hasn't checked them!

Also worth checking for broken springs in 2 port zone valves or 3 way valves not seating/passing and restricting flow.

@f1p 

I would appreciate some clarification on a few points:

1 At time of forwarding the Detailed Report the pump setting was 3 and the flow rate 11 l/min. Were you able to see a different flow rate on the detailed report?

(I have now increased this to setting 5 and 16 l/min, so would a further detailed report be useful once things have settled down?)

2 Is the flow rate on my display a specified figure at a setting or an actual flow rate? (Note that in an old note to myself I had said setting 5 corresponded to 25 l/min)

3 What would cause the Ecodan to "modulate it down"?

4 As reported, I can find nothing to switch off the second pump which you record, but I can see a hidden menu item for selecting reporting on multiple pumps, here.

Is that what your system is seeing?

5 The strainer is not very accessible (see below) and may require removal of the main PCB so I need to be sure I am on the right track before tackling this.

Posted by: @davidalgarve

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1 At time of forwarding the Detailed Report the pump setting was 3 and the flow rate 11 l/min. Were you able to see a different flow rate on the detailed report?

Without the adapter installed there is no flow rate information available to plot on the graph (as MELCloud does not record it)

Posted by: @davidalgarve

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2 Is the flow rate on my display a specified figure at a setting or an actual flow rate? (Note that in an old note to myself I had said setting 5 corresponded to 25 l/min)

Service > Running Parameter > "540" reports Flow Rate in l/min

Pump speed PWM setting (1-5) is no certainty of actual flow rate, but it will be directly linked

Posted by: @davidalgarve

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3 What would cause the Ecodan to "modulate it down"?

When flow temperature is approaching overshoot of setpoint

Posted by: @davidalgarve

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4 As reported, I can find nothing to switch off the second pump which you record, but I can see a hidden menu item for selecting reporting on multiple pumps, here

 

Is this a cross post with someone elses suggestion? I'm not sure we wanted to - i haven't checked the Hydrobox schematic as to see if there is a zone pump in addition to the primary circulation pump

Shame that strainer is difficult to access

Posted by: @davidalgarve

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4 As reported, I can find nothing to switch off the second pump which you record, but I can see a hidden menu item for selecting reporting on multiple pumps, here

 

Is this a cross post with someone elses suggestion? I'm not sure we wanted to - i haven't checked the Hydrobox schematic as to see if there is a zone pump in addition to the primary circulation pump

Shame that strainer is difficult to access

I was just wanting to eliminate any possibility that the second pump being reported (removed when buffer tank modified) could be influencing the flow rate of the remaining pump.

Further to this, would Mitsu change the flow rate of the pump depending upon whether a buffer ("mixing") tank was being used? Considerably less resistance in a buffer compared to e.g. multiple radiators. Will try dip switch 2-6 tomorrow.

Posted by: @davidalgarve

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Shame that strainer is difficult to access

Madness, like putting the oil filter somewhere that necessitates removal of the engine before cleaning it.  Unfortunately, inconvenient as it is, it will need to be checked.  Mine, after just six months in a system that had been well flushed, was totally blocked.  Perhaps consider fitting an additional external strainer so that the internal one is 'protected'?