Hi there,
I've installed Mitsurunner on a MXZ-2F42VF3 multisplit in southern Germany. Outdoor temp is mostly around 0°C.
Mitusurunner's prevention of frequent defrost cycles works very effective.
But it seems, that faking the outdoor air thermistor interferes with the logic of Mitsubishi's power control:
With
Mitsurunner active the compressor Ramps up quickly to very high power, the room temperature rises quickly and above the set point, so the unit switches off. After a few minutes the cycle starts again. Power consumption doesn't drop below around 600 W. This behavior observed with outdoor temp around +3°C or any lower temp. When outdoor T is higher, the unit works like with deactivated Mitsurunner
.
With
disconnected Mitsurunner's relay-PCB the MXZ is running continuously with lower power and the compressor frequency is smoothly controlled to maintain room temperature .
In this graph mitsurunner was connected until around 10:45, then I've removed relay PCB without switching off mains power. The spike few minutes before 11:00 is a defrost cycle.
Näytä liitetiedosto 104932
In this graph temperatures are shown (sorry for German caption, green is exhaust air temp, blue inlet air temp and yellow heat exchanger temp).
Näytä liitetiedosto 104933
The graphs shown are typically for the behavior with active/deactivated Mitsurunner in my installation. The on/off cycles keep going even for hours, so there is no self-learning process over time. Settings of indoor units have not been changed during the data record period.
It seems that Mitsubishi's control logic detects some inconsistency on the parameters detected (eg temperatures of refrigerant do not rise as high as expected with the (faked higher) outdoor temp)? I do not know! Maybe it works better in installations with higher demand of heating performance (I'm living in a well insulated flat with Neighbors that seem to love high room temperatures. 20°C without any heating...) Maybe the fuzzy logic of an MXZ unit is different to MSZ which are obviously more common in northern regions.
Are there any users of MXZ units using Mitsurunner? Are you experiencing the same issues?