Worcester Bosch internal wiring query relating to an external UFH pump

Spoke to Worcester Bosch a few months back and was told I can wire m
UFH pump directly in to my 40CDi boiler, so that when the internal pum fires up to circulate the water, the UFH pump fires up at the sam time.
Have been trying to get my local WB installer to do the work, but a 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 ou myself and see the internal pump has your typical T&E supply and then additional wires (black, white and purple) that control it. The externa circulating pump of my UFH has the T&E power supply only.
So... query to all WB installers/servicing guys or people just in th know... how will it be expected that the guy I get round to do the 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
-- Cordless Crazy
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The internal pump in the WB is probably a 3-speed pump. Instead of a selector switch, the separate wires are taken back to the control board so the boiler can change the speed itself, to get optimum return temperature for condensing operation. This is how my Keston works anyway.

Not familar with that boiler, so can't comment in detail. Some boilers have a connection for an additional external pump. Another option would be to run it directly from the room stat call for heat output, if that runs at mains voltage.
--
Andrew Gabriel

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