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hcgrande avatar image
hcgrande asked

Control Water heater with Shelly 1pm

In my boat I have a CerboGX and a Multiplus 2000 with only one 240v Output. Today the I need to manually turn off the water heater when the Inverter is running to prevent the heater to drain the battery.
Will it be possible to use a Shelly 1PM connected to the heater and Controlled by the Cerbo GX? Initially I would like to make the Shelly automatically turn on when the shore power is connected, and turn off when shore power is disconnected.

Anyone with similar system that know if this is possible?

cerbo gx
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3 Answers
johnny-brusevold avatar image
johnny-brusevold answered ·

Has something of the same, but somewhat simplified. A 240v relay connected between the mains and the water heater, which is activated when shore power is connected.

The relay has a 240v control voltage so no electronics are required.

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matt1309 answered ·

Hi @HCGrande


I also do similar with shelly 1 (not pm version but cant imagine that'll change anything as long as you're water heater is below shelly's rating).

I turn on water heat if system hits absorption phase/starts exporting power and control the on/off in node red rather than using assistants.

I use node red running on venus os to turn on the shelly (via HTTP node in node red).

Happy to share specifics if helpful.

However i think @Johnny Brusevold has the best solution if your criteria is only ever going to be "if grid connected". If you've got more complex critiera then node red might be the way to go.


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hcgrande avatar image
hcgrande answered ·

Thanks for reply´s. Looks like a relay would be the easiest part for my installation :-)

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