I’d simply try because you likely will not find out another way (have you ever seen a vendor tell about its product’s startup current ?) and worst possible thing is you burn a $15 device. Place it outside just in case If you want to play it safe you can add a relay right in the first place.
For my garden application (several pumps, airflows, lights etc.) I’m using 8port relay switch for RPi. Work for ages without any issues.
similar to this:
Yes it needs RPI, but as my garden rpi serves temperatures, garden control and squeezelite from LMS server to gardenl it’s definite choice. Runs on RPI2 to this day 4years, last two or three on DietPi + MQTT + nodered, controlled by OH on my docker production nas.
What pump do you have for starters? If the heat pump is fairly new then it should be an inverter, therefore it won’t pull a high starting current. I have my hydro pro p6/32 heat pump plus sand filter running off a Sonoff powr2 just fine.
I am using a Sonoff TH16 with Tasmota firmware for this exact purpose toggling a Steinbach Speed Clean Classic 250 pump with 200 watts. The pump was switched on two times a day for the whole last summer without any issue. The TH16 has the bonus of providing a waterproof temperature sensor.
I don’t think that you can damage the pump. It either has AC power or not. Even if the relay has a total meltdown and connects everything together the pump would not have a different voltage potential between the two pins. And then the circuit breaker would take over anyways
not really about watts, but amps … sonoffs are using 16A relays, which is more than enought for basically anything of home/garden appliances.
My industrial rated water pumps have 6A to start, that’s why I’m using 10A relays, no need to have more on those.