Spoke to Worcester Bosch a few months back and was told I can wire my UFH pump directly in to my 40CDi boiler, so that when the internal pump fires up to circulate the water, the UFH pump fires up at the same time.

Have been trying to get my local WB installer to do the work, but am having difficulties getting them booked in due to being very busy. Naturally the ground floor is pretty cold at present.

As a guy who turns his hand to anything, I have been checking it out myself and see the internal pump has your typical T&E supply and then 3 additional wires (black, white and purple) that control it. The external circulating pump of my UFH has the T&E power supply only.

So... query to all WB installers/servicing guys or people just in the know... how will it be expected that the guy I get round to do the 5 minute job will wire it up?

Just out of curiosity that is, so I can make sure he does it right! :-)

What do each of the black, white and purple control wires do?