You might get also good input in the respective reddits: /r/8266 or /r/esp32. I found those very helpful when working with esp modules and power requirements.
it will work i am not saying it will not … but after some time the relay will die…
i found this… but i am not sure i can flash it… and i need MQTT
it is rated for 32 amps , so i think its covring my load
That was not what I meant. Put a classic, dumb relay behind your Shelly.
ok so i did not understand…
what is a dumb relay? , i guess we both have diffrent things pop up in our heads 
Well, for a start, it’s an electrical device and not a person … those are not so reliable in relaying 
Put “relay 230v” up as a search on Amaz*n and you’ll get various offers. Many of those actually have the circuit even printed on the enclosure so you’ll understand how that is supposed to work.
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thanks i will look into it
Why? The whole point of openHAB is to match these things up. It doesn’t matter if everything else runs MQTT and your relay runs Modbus-TCP, so long as it turns on/off when told.
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.
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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.
Hello my heatpump has Wifi out of the box…
the issue is my filter pump… its underground … i will have a look today for exact specs
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.
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If it really fails one day I am positive that I can just replace the relay with a better one or just buy a new Sonoff and add an external dumb relay.
i am sure it will work … and i have a bunch of TH16 laying around
but i am trying to do it right …
i am not an electrician, but how do you know you are not damging the pump itself?
for me to replace it will be a nightmare … and its already very old
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
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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.
The issue at hand beyond current handling is the reverse voltage spike produced when the inductive load is switched. You can put a dedicated surge arrestor power bar off the sonoff and then plug the pool filter into that
please no big words 
. You can put a dedicated surge arrestor power bar off the sonoff and then plug the pool filter into that
if you can please put this in more noob terms
and thank you!
This pump will melt the 16A relay pretty soon. The starting current would be in a range of 30 to 50A. I also tend to derate the Chinese relays by at least factor 2. You are better using a motor contactor that you control with some cheaper WiFi switch.
Tell us more about the existing relay … with a view to re-using that by controlling it, leaving the power side wiring alone.