I think that they have to be paired with the zone that they are controlling. How else would they work? It wouldn't help if two neighbours got theirs mixed up.

I concur - if they're not paired they shouldn't  interfere (which is why they usually sell the thermostat and receiver as a boxed set - the come factory paired).

  - Andy.

I only have experience of the Honeywell T4R, and as Andy says, the programmer and receiver come as a factory set pre-bound pair, so as long as you install both receiver boxes to operate the boiler they should work independently (although I am not sure if this will achieve what you want).

In my  house I also have three wireless controlled shower/bath thermostats that work on the same frequency band.  They don't to interfere with each other or the programmer.

David

Cheers guys.  They are to operate 2 separate zone valves.  i'll give it a try.