I've asked this question in both Plumbing and Electrical as it falls technically under the remit of both. I have presently mounted on my wall A Danfoss TS715si Electronic Single Channel Timeswitch I have bought a Danfoss RET230 Electronic Thermostat. Basically I want my setup to perform like this. If Timer Is On AND Thermostat Is Calling For Heat Then Turn Boiler On. Or Else // Keep Boiler Off. I provide a few diagrams to show you how I think it should work. I think Configuration 1 would be correct but I just want to run it by a few people who do this for a living just to confirm. I know that I should have bought a Programmer but ultimately I like the challenge and the idea of a manual thermostat than a digital one.