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david-bossu avatar image
david-bossu asked

multiplus compact 12V 2000VA - how to isolate water heater while inverting

Hello,


I am installing a multiplus compact 2000VA, 12V, 120V on a sailboat.

In previous installation using a 3000VA model, there was an AC-out2 output that was not powered while inverting. Since I want the water heater to be powered only by the AC-in, not by the inverter, it was easy to just connect it to AC-out2.


There is no AC-out2 on the compact 2000VA.

How would you recommend I integrate the water heater in the system? the idea is not having to use a source selector switch (ie shore/inverter rotary switch) .

Is there a way to program the aux relay so it's on only when inverting (AC-in off)?

this way, I can use it to control an external relay, with the water heater on a normally close contact. when it's inverting, the contact opens and disconnects the water heater.

Any help appreciated.

David

Hot Water Diversion
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6 Answers
oceanwolfe avatar image
oceanwolfe answered ·

Isn't it simplest to just add a receptacle in the shorepower line before the Multiplus and plug the water heater into that? When you aren't on shore power it won't heat water, when you are it will.

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david-bossu avatar image
david-bossu answered ·

I thought about this but then the cerbo GX display will not accurately show how much power is drawn from the shore power if the energy utilized by the water heater doesn't flow through the inverter-charger

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hjohnson avatar image
hjohnson answered ·

On our sailboat, we gave the hot water heater its own breaker (it should have its own anyway). So, sitting here at anchor, we have the tank breakered off to preserve battery. However, given our intention to motor a long way tomorrow, we’ll probably turn it on to do dishes tonight.

Next engine will have a freshwater coolant loop, so it can heat the hot water tank while we motor directly.

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david-bossu avatar image
david-bossu answered ·

Back to the original question, is there a way to program the aux relay so it's on only when inverting (AC-in off)?

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colin-jones avatar image
colin-jones answered ·

You can use the programmable relay assistant to switch based on AC-In available or unavailable, which is logically the same as a model with an AC-Out2.

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klim8skeptic avatar image
klim8skeptic answered ·

Wire the coil of a contactor across the mains input?

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