Have a Worcester Heat Slave combi 18 yrs old and am looking to replace with condensing combi.
Would like to flush my system and replace TRV's and Lockshield valve my self to save some money.
Is it his reasonable? I am good at DIY and have most tools.
I realise that this system is unvented, does this make it harder to do? any explanation welcome. Thanks Martin

Martin King, August 2008

Not really.Turn off 1 small rad at both ends and drain.Fill this rad with the inhibitor,turn valves on again ,top up system and run it for however long the inhibitor maker says.Then empty system and remember to fill and empty 2 or 3 times.
Do this before putting the new TRVs on.

Gasman, August 2008