My existing WiFi room 'stat has reached its near-end of life, so I bought a Honeywell unit to replace it. I read up on what I had to do, I powered up the remote unit to make sure it was working, and then proceeded to remove and replace the old Relay box, which of course meant that I had to cut the old Lucar connectors off, as the new unit just needs bare wires inserted into terminal blocks.
The manual* details the start up procedure, which includes confirming that the Remote and the Relay Boxes communicate. They failed, several times. There is a procedure to re-establish setup data and communication, which it calls Binding, and although I followed the procedure, it failed every time. I accepted that I would have to restore the old system, so I went out to the garage and retrieved the new connectors and crimper.
I am firmly of the belief that equipment can be frightened into working when it is threatened with replacement, so I tried the Binding process once more, but it never completed the procedure as described. But then, as I was shutting everything down, suddenly the boiler started up without warning. I adjusted the Temperature setpoint, and the boiler responded correctly. The units still fail the Communication Test, but there is an icon of an antenna on the display, and it appears to be working.
The old unit has no name, I know it came from Toolstation several years ago (about 2012). It had a communication indicator light and a Heat Demand light. The Honeywell has no communication light, but is supposed to have a Heat Demand indicator in the display, which is missing in action. But it does have a Relay On light, which is basically the same thing.
As the Americans would say: "Go figger!"
- In common with most manuals, if you can find them, this is a multi-lingual sheet, with hardly anything written, but lots and lots of diagrams of fingers pointing at buttons. It takes some time to work out what it is actually instructing you to do and see.