I've been using evohome for a while and it works well - but I've been frustrated by an inability to modulate the temperatures - either I run a low boiler temp and have trouble heating when it's cold, or go high and lose the condensing efficiency.
My boiler is a Rinnai E32S and the manual claims it supports OpenTherm, and it has two connectors marked "OpenTherm" so I'm fairly confident it should work. Rinnai sell an "RS100" controller which connects there and sounds like it might use the OpenTherm protocol.
I bought an OpenTherm bridge and connected it up. Initially it flashed red as expected; I bound it and it started to give three red pulses at a time. I figured this might be "can't talk to the boiler" so turned off all the power, and when it turned back on it was flashing green as expected.
However, the boiler is not behaving as if there is any OpenTherm control at all. When I disconnected the valve microswitches that normally cause the boiler to fire, it did nothing despite there presumably being demand (at least, the BDR91s had opened the valves). When I reconnected them it fired up to 85C (I'd set the max temperature to 85C as according to the RS100 documentation the boiler fires to the lower of the OpenTherm temperature demand or the max setting)
Even when there is no hot water demand and very little heat demand (only one HR92 calling for heat, with a setpoint 0.5C above the temperature) it fires to 85C. The RS100 manual suggests that when the boiler is under remote control it ignores the heat demand contacts.

There isn't much scope for debugging - I have the old Evohome controller (non-wifi, Jan 2014 software). When I do an RF test of the opentherm bridge, I get 5 red flashes on the bridge but no indication on the evohome controller to say excellent/good etc (with the BDR91s I get "Excellent (2)" - though the help text on the evohome controller suggests that there will only be an indication on the bridge itself.

Grateful for any advice. Are there any other tests I might be able to do?