Its not so much about making it UV stable more to do with keeping it water proof ,moisture in the lagging will freeze and transfer the cold to the pipe
Just something to be aware of
although the grey should be permanent live then giving power to orange when microswitch made
A lot of people wired them up as orange perm live giving power to grey when microswitch made .
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As you have already changed the valve head
Your first port of call...
you have now contacted him several times and they are lying to you the condense needs lagged not just outside but actually through the wall . So tell him you are contacting gas safe for them do do the free inspection or dont give him the heads up and just do it . He will be made to alter...
£1368 quid to fit those two parts ? if so someone is pulling your pants down
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If you got a new combi then you wouldnt need those parts as they are incorporated within the boiler
Ideal classic is one of the best boilers ever made