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MultiPlus 3000 Aux Output programming and Wiring

425 Views 10 Replies 4 Participants Last post by  nebulight
I am looking for help from the Victron experts. I have MultiPlus 3000 and have the AC out 2 going to a 20 amp breaker and feeding a water heater. I would like to have the inverter power the water heater when there is less than 500w of output from the inverter and turn off the water heater when there is more than 500w of load on the inverter. This will let the inverter heat water but stop the inverter from going into overload when another load like the heat pump or microwave are on. The HWT currently has a 2,000w element but it can be changed out easily to lower the wattage. If I can make this load shedding work I would rather leave it so that the water can heat quickly, especially when we are plugged in and have 6,000w available with the power assist.

I have tried to set up an assistant to do this, but I am only seeing AC load as a trigger, not the inverter output. Is this possible? I think I can add another assistant to have the AC out 2 always on when shore power is available to get around it but so far I am having trouble getting it to work. It seems that this question has been asked before in the Victron forums but I am hoping that someone here has actually done it. Is it possible to use the inverter overload warning as a trigger to turn off AUX2 ?

I added a second breaker box to allow for a 30a shore power breaker and to keep the AC out 2 separate.

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2016 3500 ext-ht
1,350 Posts
If you ever decide to modify, the isotemp water heaters that heat the water with using engine coolant is the way to go for people that plan to be driving often. I have had two class B RVs (1989 Dodge factory built, 2018 Promaster Self Built) and have had heat exchanger water heaters on both. I will never have an RV with an engine without one.

The electric element on them is only 750W (at least on my model) but if you drive every two days you will never need the electric element anyway because it heats the water to engine temp and keeps it hot for quite a while.

As Nebulight put three assistants may work, I haven't ever set up ones that conflict so I don't know how it behaves when one tells it to turn on the AC2 relay because it is connected to shore power and the other says to turn it off because of >500W load. He might know more than me on this one.
Can you use Demo mode? I have never used demo mode for assistants.
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