2022-07-19

How did the aircon cope?

Well, it coped quite well.

The red line is the temperature at my desk, which I was aiming for 22C. In practice the floor ends up around 20C.

The interesting bit is the blip around 13:00 where it got colder. It seems that the aircon is not doing what I expect. In order to control the temperature at my desk rather than at the wall controller or the air inlet in the loft, I tell the aircon a target temperature. When too cold I tell it to to cool to 5C higher than the wall controller. When too hot I tell it to cool to 5C lower than the wall controller. This works to turn the compressor off or on. But as the inlet (pink line) got hotter we got to a point where telling it to cool to 5C higher was not turning the compressor off. This means that it is clearly using the inlet as a reference, or possibly inlet and controller average. The inlet is interesting as (being ducted) the air leaves my room, via some ducting in to the aircon in the loft, and the loft temperature was up to 40C, meaning the inlet temp sensor was way hotter than the air actually leaving my office.

This is rather annoying as there is an explicit field setting to tell it what to use as a reference and that is set to the wall mounted controller. The fix was to change my code to allow me to expect the reference to be the inlet temperature or the controller or average of the two. As you can see, that fixed it.

However, from around 14:30 it was not going below 22C. The thicker line is my code making the fan speed higher in an effort to get it to go down to 22C. The compressor was on and the coolant was cool. But it was struggling. My office got up to a roasting hot 22.4C :-)

All this was on one of the hottest days of the year. So, yes, I think it is working well :-)

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