Hi All,
I am in the process of trying to get my Vaillant AroTherm Plus 7K to cool…
We have installed the cooling chip in the main ASHP and have activated cooling in the installer mode menu on the vr720f but when we try to get the unit to cool either in manual, timer or by forcing it to cool via the “Cooling for several days” the ASHP doesn’t react???
Does anyone have any experience with this?
Hi Alan,
You didn’t by any chance buy the “cooling chip” Vaillant Part Number: 0020266328?
As this is the one I purchased and had the same issues, although the site I purchased from said it was the cooling chip, the part number is different from the one I on the midsummer website, and as you say “the ASHP doesn’t react”.
I’ll be interested to hear from others if they have this one or a different part number.
No I brought this one (0020269259) but it looks like a lot of people have issues getting the Vaillant AroTherm Plus to run.
The plug is just a resistor, it should apparently be 4K ohms. Are you able to measure the resistance of your plug? It should be possible to just use a 4K ohm resistor instead of the plug.
@myatix Cooling needs to be enabled on the ASHP controller too. In my case that is via the Unitower panel’s “installer level/configuration/cooling technology/“ setting which should be “active cooling”.
Have you checked this setting?
Hi Andy, Yes already done that!
Hi Glyn, Thanks for the response! I dont think it’s the plug that’s the issue. I can see all the additional cooling settings in the controller which I didn’t get before. It seems to be to do with the settings/ firmware or similar???
I think I have found the issue!
There is a setting called ESCO (Energy Supply Company) under “Settings > Installer > Installation”
This was set to “Cooling Off”. It was my understanding that ESCO was used by electricity supply companies to disable curtains appliances if there was an energy shortage. It would appear that this is not the case or doesn’t work as settings the ESCO setting to Cooling Off disables cooling on the AroTherm Plus.
“ Define what you want to deactivate when the signal is sent by the energy supply company. The selection remains deactivated until the energy supply company cancels the signal.
The heat generator ignores the deactivation signal as soon as the frost protection function is active.”
On another note does anyone have any good experience setting up cooling for Underfloor heating with a 100mm concrete slab?
Minimum Flow Temp. Etc etc???
We have natural wood floors so I am a little concerned about condensation which could cause the floors to cup ( warp)
Any advice would be greatly appreciated!
Do you have the myVaillant app? Even when “cooling for several days” is on, there is a separate cooling toggle. I don’t know exactly how zo do it on the hardware controller, but the “cooling for several days” being on does not mean that cooling is on all the time, it just allows cooling in that time window.
I am working on that! The App states that there’s a gateway update in progress that can take up to 24 hours… 
What takes 24 hours to upgrade with a fibre connection these days??? (Potentially 14 hours left before the update is complete.)
Can the Cooling be run on a heat curve? It would be nice to see this feature especially with UFH which can have a significant lag if used with manual settings.
I don’t think there’s a heat curve, for me it’s just setting the minimum flow temperature in the installer options and that’s the target flow rate it will use. It can dip quite below that so if condensation is an isue you have to watch out. There should be a dew point sensor in the controzas well which goes into the cooling (not for me as my controller is in the basement).
Yes the VR720f has a dew point sensor in the controller. You can see the dew point increase while holding the unit. 
I will start at 18 degrees and slowly reduce the temperature I think.
I am also considering installing a condensation sensor on the pipe work to shutoff the unit if condensation starts to appear.
You might want to consider using a signal on MI to achieve this: c.f. HP control module configuration/MI/Ext cooling mode. If you work out exactly how to provide the signal perhaps you could let us know: I keep meaning to ask Vaillant exactly what they mean here, and exactly which connector MI is on which board!
Good spot on the ESCO setting. This is exactly what the VR720/3 manual now says, once you decode the Vaillant speak of Section 2.8. I suspect some installers might misinterpret this section to imply that the ESCO setting should be as you found yours.
Hi Andy,
Thanks for the feedback… The MI is on the VWZ AI Controller… You have M0 and M1… If you look under the “Settings > Installer Level > Installation Configuration > HP Control Module Configuration > M1” menu you will see an option to set that too: “Ext. Cooling Mode”
I guess you can connect a switch or some other device to the M1 wiring terminal on the VWZ AI??
@Andre_K Can I ask which gateway model you are using for the myComfort App. I have a SensoNet VR921 (0020260963) and I just cannot get it to connect to the App. I noticed that there are 2 different VR921 models… One for a Gas Boiler and another for ASHP… I am a little worried I have the wrong version???
Thank you, that is clear for the standalone VWZAI unit and the associated manual also details the board connector to use. The board in the Unitower plus is different but, thanks to your hint, I found the most recent Unitower plus manual and that now includes reference to MI being on X41 connector. Progress!
