Ecodan and Mitsubishi PUMY cooling ena

[AhMario]

Hello all, I am writing to check if there is someone who maybe went through the same case I am in.

 

I have a UFH system based on Ecodan internal unit (ERSC-VM2D.UK) and PUMY external unit (PUMY-125VKM5).

Heating in winter is working very well and energy usage is so far quite low, I am very happy of the system.

 

Now I would like to use the system to cool the house using the UF pipes but I am no pager sure it is really possible..

 

I did the following

1. enable cooling mode in Ecodan by setting SW4 switch

2. Switched operating mode in Ecodan to cooling and I set target water temperature to 16c, 10c less than current temp.

 

the result is that the cooling never starts, no error in display.

Ecodan display just permanently shows the “pause symbol” next to the cooling icon.

I tried to force external request of energy by closing circuit on ecodan IN pins, the pump indeed starts but the cooling still stays in pause.

 

has anybody succeeded in using this PUMY external unit to cool water?
 

I start to doubt that this is not possible..

1. In the design phase technician told me that this would be possible.

2. Mitsubishi staff is now saying that the external unit does not support water cooling and the only way to use it to cool something is to add branch boxes and splits

3. Mitsubishi website states that water cooling is possible for this very external unit

[PhilT]

Could it be that the dipswitch setting you changed only controls the internal unit, and the external unit has its own separate dipswitch (or other) hardware settings which need to be changed to cooling mode?

[Gary68]

What is calling for 'heat', you may find that you need to increase the temperatures on your thermostats to call for heat which will tell the heat pump to turn on and then cold water will circulate round the system.  That's how it works with my air to water heat pump.

Edited July 22, 2024 by Gary68

[AhMario]

Thanks, I will check both items!

[AhMario]

Still no success..

I checked switches configurations in external unit and branch box, everything seems ok.

I tried the temp increase check but it did not work.

 

BUT I discovered something difficult to understand: now the system would not even heat water for UFH…

If I set mode to heating and Inset target water temperature higher than current reading behavior is same as the one I am experiencing for cooling: everything in standby.

[PhilT]

  On 24/07/2024 at 12:03, AhMario said:

Still no success..

I checked switches configurations in external unit and branch box, everything seems ok.

I tried the temp increase check but it did not work.

 

BUT I discovered something difficult to understand: now the system would not even heat water for UFH…

If I set mode to heating and Inset target water temperature higher than current reading behavior is same as the one I am experiencing for cooling: everything in standby.

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Did you power down completely before changing settings (or at least power off/on after changing)?