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straycat avatar image
straycat asked

How to best connect a 240 v hot water system to remotely start via Cerbo Gx

Hi,


I’m still very new to this. I’m wanting to connect a 240 volt hot water system to a relay port on the Cerbo Gx. I would like to activate it remotely (when I’m on the way to the boat)

Can someone please advise the best way to write this? I imagine the Cerbo can’t take all the hot water current and will require an external relay.

Please provide support on how best to do this

cerbo gx
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2 Answers
matt1309 avatar image
matt1309 answered ·
I personally do this via a shelly smart switch rather than using the relay built into the cerbo (you may be able to do it but I found using Node red with shelly smart switch more flexible).


I connect shelly smart switch to water heater, then using Node red in cerbo to send Http request to shelly to turn on the water heater when i have excess solar. However Shelly have their own cloud for remote access to the switch directly but also supports MQTT/cloudless (if that's more your thing), which allows you to remotely activate it while away via internet connection


I also utilised the auto turn off timer in the shelly smart switch (I set mine to 1hour), just in case the messages from Node red/cerbo get messed up some how the switch will auto turn itself off after said auot turn off timer (for me 1hr).


I'm not sure if you can activate the cerbo relay via node red but if you're buying a secondary relay (larger for water heater). Then shelly might be a solution that's worth looking into. (16amps i believe is the max of the standard shelly switches)

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ponzoa avatar image
ponzoa answered ·

I use one of the relays in the cerbo to activate a contactor/solenoid which switches on or off a resister with a termostat so it won't "boil" the water. I can activate it or switch it off via VRM with full control

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straycat avatar image straycat commented ·
I have read that this can fry the Cerbo relay and that a diode must be used. Did you use one? What size solenoid did you use?
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