On Fri, 02 Jan 2009 10:55:10 -0800, yekal_tytwr wrote:

Hi All,

We are building a house with wet underfloor heating which goes back
to 2 control units, which have all the wiring completed, only leaving
2 wires from each unit going back to the boiler (volt free). the
boiler has now been installed (Worcester Greenstar 12/18)

Is that an oil boiler? I don't recognise the model name as a gas one.

... which I
could not find any volt free connections, I spoke with Worcester bosch
technical today and all they could tell me was that the boiler doesn`t
have the appropriate connections, but could not tell me how I could
resolve this problem.
Anyone shed any light???.

Not sure what your UFH control units require. You say they want volt-free
connections but not whether the connection is a signal from the boiler to
the UFH controller or the other way. If the former maybe the UFH
controller has its own mains power for its pump and just needs a contact
closure to tell it to run the pump. In that case I'd be thinking along
the lines of fitting a pipe thermostat to the boiler's flow pipe to tell
the UFH when there's heat coming from the boiler.

Alternatively if the volt-free connection is a signal /from/ the UFH
controller /to/ the boiler from a set of contacts in the controller, then
I'd think along the lines of connecting across the boiler's LS and LR
terminals.

I think you really need to scan and post the UFH instructions somewhere for
us all to see (or point us to the mfr's docs online).



--
John Stumbles -- http://yaph.co.uk

A: Because it messes up the order in which people read text.
Q: Why is top-posting a bad thing?