Over heating settings - what exactly does it change? + EEV lifetime?

[landrysik]

Hi, I am trying to understand the logic behind the AC's internal algorithm that regulates the actual compressor power. It is (should) be closely related with the "over heating setting" but what those numbers even mean? (+4/+6°C). What happens when the tempeature is (presumably) +4°C from setpoint and what happens at +6°C? What are the default (0) values? I am using LG Standard plus PC12SK

I have it set to +-1°C in hopes it will better regulate indoor temperature and I first thought it will just get to the setpoint +1°C and slow down the compressor and if it gets -1°C from setpoint it will speed up. But the "black box" is more complicated than this. When the temperature started to rise quickly I was still -1°C from setpoint and at this point the AC lowered compressor power.

Does anybody have more observations? Maybe we can get a better picture how it works together. One observation I can share is from before I started using this wired controller: I hardwired the actual thermistor input to fixed resistor to simulate 31°C. When set to 30°C and turned ON, the AC started at nominal power (around 900W input) and stayed there forever. When I wanted lower power I set the fan speed to low and the AC lowered power to around 500W within few minutes. When I then set fan speed back to HIGH it kept the 500W again forever. After defrost it started again at 900W. Why 30°C? because at JET fan mode the compressor power stayed the same (900 or 500W) and I got high fan speed. Btw interesting is that the actual power consumption actually drops by 100W after turning on the JET mode - presumably because the internal coil gets colder, pressure drops and the compressor does not have to work so hard even at the same speed (rpm/frequency). The opposite can be observed when lowering the fan speed - consumption immidiately starts to rise until some point when the AC decides to lower the compressor speed.

It is honestly really hard to get relevant data with a repeatability to understand the behaviour because sometimes even after power cycle the AC sets different power level even with the same setpoint + same measured temperature. Maybe outside temperature plays a role aswell? Or pipe temperatures/pressures/ time from the last compressor start?...

I tested the workaround template sensor that fakes the temperature reading but in my conditions it didn't work that great. The AC was constantly modifying the power up and down.* Maybe it should be "tuned" to specific room and the thermal inertia.

To work around 2), if the temperature drops below setpoint - 0.1 and it has been heating for more than 10 minutes, it forces the unit to work harder by reporting setpoint - 2.5.

I got a feeling that 2.5°C with just 0.1°C difference was too excessive. The AC started ramping the power too quickly and too much and overshoot the target temperature. It got me thinking that maybe report setpoint -2.5°C but only for a few minutes to get the AC power going up and then lower it to only setpoint +1 or even real temp so it won't ramp up that much? I have to test it further but we currently have quite a warm weather...

* EEV?

And one more thing to consider. As we see the AC is really lazy changing the compressor speeds. It likes to set one speed and let it run for hours even when the temperature is fluctuating. This got me thinking that maybe the manufacturer set the software this poorly on purpose! I am not a HVAC expert but the EEV (Electronics Expansion Valve) needs to change position every time the pressure changes to maintain ideal pressure difference for refrigerant evaporation. So with every compressor speed change the EEV needs to change aswell. And those EEV's have for sure limited cycle lifespan. So in typical conditions, even "shitty" EEV and compressor system can last projected 20 years or so...But once we start to mess with the AC by reporting fluctuating temperature and force it to change the compressor speed every 10minutes, those 20years can quickly shrink to much less.... Maybe I am just overly cautious but be aware of this aspect...