Multi-Unit Controller Kit - Expandable System for 5 to 25 Units | Smart Home Automation & Industrial Equipment Control Solution

I have two Rinnai R53i connected together. My intention was to use this klt to be able to adjust the temperature of both with one control and also enable one as default and two as more flow is needed.I could not make it work. I spend a lot of time with Rinnai people and no success. Initially we though the board was defective, Amazon was great and replaced the Kit without any extra cost. The new kit behave the same.In suma, no complains with Amazon only appreciation for their service. My 2 Rinnai are new (was a house that took 9 years to build! and therefore these Rinnai bought few years back have not been used) they work OK, just seems that they are not compatible with this kit despite RInnai assurance that it "should" work.