Connecting to Window A/C Unit

mpersson098 · July 12, 2019, 12:06am

Hello everyone!

I currently live in NYC and my a/c is a typical window unit. Like most people in NYC central a/c is harder and more expensive to come by. My question is, is it possible to connect HestiaPi to a window a/c unit? Or somehow trick the software to think it is the central heating and cooling unit??

I would need to connect the a/c unit to a smart outlet so it can be controlled over wifi, but any ideas how I would control it like I would a central a/c unit? Is that even possible??

Thank you for your help!!

Michael

HestiaPi · July 12, 2019, 12:28am

If your AC unit can be set for temperature and turn on when power is connected, then you are fine.
One way is to wire the AC contact from HestiaPi to an external relay rated for the power of your AC and connect it to your AC unit. Simple as that, but this is the “wired” option.
To go wireless, you can get these Sonoff basic relays (5-10 bucks) and wire it up to your AC. It communicated over WiFi but a few more steps are needed. First is flashing custom Tasmota firmware on Sonoff (plenty of youtube videos). Second is telling Sonoff which MQTT topic to subscribe to, aka which command to listen for from HestiaPi. The full command is in your items file (in /etc/openhab2/items/default.items) at the CoolingPin line

github.com

HestiaPi/hestia-touch-openhab/blob/master/home/pi/scripts/default.hvac.items

Group charts
Group chart_temp
Group chart_humi

Switch HeatingPin "Heating" { gpio="pin:12", mqtt=">[mosquitto:hestia/local/heatingstate:command:ON:1],>[mosquitto:hestia/local/heatingstate:command:OFF:0],<[mosquitto:hestia/local/heatingstate:state:MAP(binary.map)]" }
Switch CoolingPin "Cooling" { gpio="pin:23", mqtt=">[mosquitto:hestia/local/coolingstate:command:ON:1],>[mosquitto:hestia/local/coolingstate:command:OFF:0],<[mosquitto:hestia/local/coolingstate:state:MAP(binary.map)]" }
Switch FanPin "Fan" { gpio="pin:18", mqtt=">[mosquitto:hestia/local/fanstate:command:ON:1],>[mosquitto:hestia/local/fanstate:command:OFF:0],<[mosquitto:hestia/local/fanstate:state:MAP(binary.map)]" }

String MyTemp "Temperature" <temperature> { channel="exec:command:gettemp:output" }
Number MyTempProxy "Temperature [%.0f °F]" <temperature> { mqtt=">[mosquitto:hestia/local/temperature:state:*:default]" }

String MyHumi "Humidity" <humidity> { channel="exec:command:gethumi:output" }
Number MyHumiProxy "Humidity [%.0f %%]" <humidity> { mqtt=">[mosquitto:hestia/local/humidity:state:*:default]" }


Number TempMaxSetpoint "Temperature Max Setpoint[%.0f °F]" { mqtt=">[mosquitto:hestia/local/tempmaxsetpoint:state:*:default],<[mosquitto:hestia/local/settempmaxsetpoint:state:default]"}
Number TempMaxSetpointChart "Temperature Max Setpoint" (charts, chart_temp)
Switch IncTargetTempMax "IncTargetTempMax"
Switch DecTargetTempMax "DecTargetTempMax"
Number TargetTempMax

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These are a few extra steps but it is the right way if you want to start expanding in the trully opensource way your home automation scenario. If you don’t want to buy Sonoff and prefer doing it yourself, get a ESP3266 ir NodeMCU, flash custom firmware Tasmota and continue as above.

mpersson098 · July 12, 2019, 1:01am

Would this be true for an a/c that doest turn right on when power is plugged in? As my a/c has electronic switches and not manual on/off switches.

Thank you for your help!

HestiaPi · July 12, 2019, 9:14am

There is one test you need to do. Powe the AC on and wait till it actually starts pumping cool air out. Remove the power. Wait 30sec. Restore power. The “trick” is to be on when power is cut. Otherwise all ACs would start after a power outage. I have seen some models that have a DIP switch, not visible from the outside, that enable this feature. Maybe read any documentation on your model or ask a local professional if this is possible.
If all above fail, the other solution, which is not yet available, would be a WiFi IR emitter that will trick the AC into thinking it got the “power on” command from the remote controller. I haven’t found any such ready/cheap product that can be hacked into working with HestiaPi yet but this hasn’t been our top priority.
Let us know how it goes.