Reverse Engineer Rinnai Remote Control

[kevinvinv]

I have an REP199iN. Just installed it. As I suspected the recirc control is not going to cut it. The control-r box is not to my liking either. I want to find out how I can kick of a recirc event manually. I know I can kick off manual recirc event by unplugging and replugging the entire water heater... but that is a bit much I think.

I noted that both the control-r and the mc-195-t controllers communicate to the water heater with only two wires.

Does anyone know the mechanism by which those two wires provide power to the controller AND communicate information to and from the main PCB in the water heater? I am a circuit guy so I can envision a few ways this could be done and I know how I would do it if I were the designer but I am wondering if anyone can confirm without me having to start from ground zero to figure this protocol out.

In case you are wondering, the end result here will be a connection to my home automation system that will kick off a recirc event when motion is detected in various rooms of the house. I know Rinnai sells a motion sensor with the control-r but the prices are ridiculous and I trust the reliability of my HA system better than I do control-R (based on various reviews).

So thanks for reading.

 

[Fitter30]

Controller has to be a digital. Need someone in IT.

 

[Sponsor]

 

[kevinvinv]

For anyone who cares, I made a video of how I managed to cope with the crummy recirc that the Rinnai Tankless offers. There are lots of problems with it when you compare to a tank recirc setup in my opinion. But I have a solution that works well enough for someone as picky as me.

 

[Fitter30]

100' of 3/4" pex only holds 1.83 gallons. Looking at your graft a 5 or 10 gallon buffer tank piped in the recir line should help with the cycling. Since the minimum flow is looking for colder water. Burner turn down is producing at the lowest output its still to much. Electric water heater is already insulated and has a dip tube for better mixing don't need the relief valve or wiring.