Recently had one of these fitted with a new combi system but there
weren't any instructions in the box, the fitters didn't know how and
downloading pdfs from the invensys website (www.climate-eu.invensys.com)
isn't working for me.
First thing I figured out was the SCR override to turn the ch on/off.
Took a bit longer but I've also got the RF3 programmed and happily
talking to the SCR. The outstanding mystery is what the SCR learn mode