Antifreeze control using Faikout auto mode

[davidded]

Hello everybody,

I currently use a Daikin unit to keep a room frost-free. Since keeping it at 10° C setpoint uses a lot of energy in my scenario, and the units do not support a lower setpoint by themselves.

So I wish to use the Faikout auto mode or something similar to keep the temperature within a hysteresis window between let's say 4 and 6° C, ideally using a pre-set unit setpoint like 10° C and optionally having the eco-mode enabled.

How to do this eludes me; the Faikout auto mode has a lot of options all of which I am studying but so far to no avail.
Has anyone tried the same so far and might help me with this please?

I have had a look at similar discussions but what I am missing is how to set the min/max values for the faikout auto mode independently from the limits of the indoor unit thermostat, and (most importantly) how to have the auto mode shut down the unit instead of setting it to a low setpoint which is not supported.

Thanks and kind regards,
-David

[revk]

The main one is thermostat mode which does a traditional off when it hits top limit, on when it drops to bottom limit type working.

The set the target 5℃ with ±1℃ in the Faikout auto mode.

[revk]

OK you don't, why are you trying to, sorry if I am being thick.

[davidded]

The need for this is simple: I need to keep a room at a set minimum temperature, right above freezing. 10° is way too warm in terms of power utilization, so when we had -8° outside recently, I need to keep the room frost free but keeping it at 10° C means that at celing height I have 12-13° C average temperature, and this uses about 500 W continuously and leads to lots of defrost cycles. That's why I need this unusual lower setpoint.

[revk]

This sounds like a new setting.

A low level that forces power on and heating when reached.

I don't have that as a feature. Its is not that daft to have it. Maybe I can add a min "antifreeze" temp for that perhaps.

[davidded]

OK, that would be a great feature. Maybe it would be easiest to do this more generic by having separate temperature margins for the faikout auto mode and the unit ranges. I find that a semantically important distinction, since one is for the control logic, and one is for the limits the specific unit supports protocol-wise. Why is this important? If we set the unit to an unsupported value, it simply ignores it. This leads to difficult to reproduce behaviour.

[revk]

I'll look in to it

[revk]

I have added a prost protect temp in latest beta, please test.

[davidded]

A tricky part from this minimum runtime will be to make sure the control actually works, so we also need a larger hysteresis downwards temperature-wise.

[revk]

The a/c should be doing this itself, really. I am surprised it is not.

[davidded]

I was surprised, too, but it really seems to defrost only if it had enough time to run continuously without being turned off by the remote or the S21. Btw. did you get my email with the measurement curves?

[revk]

Yes I did - did not mean a lot to me sorry. It seems very odd to have to second guess this stuff in the a/c. A min time may be possible. I'll have to look when I am feeling a bit better.

[davidded]

Oh, get well soon!