Greetings!
Firstly, I’m new to both home automation and this site…
I need to set up countdown timers for several (independent) airconditioners.
So, my need is for smart switches on which the power circuit is normally closed so that the airconditioners can be turned on by their normal remote control.
Ideally, the smart switches sense the load and begin the countdown (for example 4 hours) then break (open) the circuit before resetting and closing the power circuit within a few seconds to enable the remote control to start the airconditioner again.
I looked at sonoff products, but the only normally closed switches I found were POWR2 and POWR3 which are too bulky to fit the switchbox.
Although this seems like a reasonable ask, the closest post I found was about Zooz ZEN15 and dated 2018.
I have a Shelly 1PM fitted to the supply to a Softub. This is both a switch and a power meter, and has basic Wi-Fi and good integration with Home Assistant ‘out of the box’.
The Shelly can be configured as standard to be normally on, which is how I have my unit as I only use it for power measurements. It stays on (power relay closed) all the time, it restarts as ‘on’ after power recycling, and I have set a unit timer to turn on every day at 11:00 just in case. If necessary I can power recycle the tub by manually turning the 1PM off then on in the Shelly app or by using an HA automation.
I have HA automations that detect the tub turning on or off. I don’t have a current need to auto control the tub heating as it does that itself, but it should be easy to create an HA automation to trigger on start, wait 4 hours, then turn off / cycle the 1PM.
I am not here to recommend Shelly specifically as it is just the one I went for.
And, of course power cycling an a/c unit may not actually work if it self-restarts as ‘on’, plus the remote is going to be still thinking that the a/c is on and is now out of sync. Probably better to try and integrate the a/c unit with HA directly.
Another vote for Shelly PM.
But most of modern split ACs do have automatic restart. Also, They are not built to be regularly stopped like that and it might not be healthy for the compressor.
Thanks, these were useful insights. I tested one of the units and it did have automatic restart, so my idea was a fail.
I’m in Cyprus, they are all split units and most rental properties have pushbutton timers in place of the isolators on the wall. So push once for 30 min, twice for an hour and 3 times for 2 hours. It’s an ugly solution which I was trying to improve on. I can’t imagine it does the compressors any good but I haven’t heard of them coming to harm.
I’m not competent to work inside the aircon controller, so the next idea is to use a 40 Amp 2 pole smart wifi switch with smartlife or tuya. The only advantage over the dumb pushbutton switch is the time limit is preset and only needs a single push.
I assume that smartlife and/or tuya can be programmed to countdown from power on, but I didn’t find clear confirmation when searching
What’s your ac brand? A few brands has HA integration, so you could probably use that to check the current state instead of relying on ir blasters or power loads
Also, how do you intend to limit the usage? 4 hours then turn it off for a few seconds?
If its a physical button that can be pushed or pressed then setup a switchbot or fingerbot and if there is a power socket nearby then you can also get a battery eliminator cable to power it that way instead of needing to worry about replacing the battery in a heavy use case.