wrote:
For what it's worth (see Ed's post) the pressure reducer on my unvented
system was 1bar and the safety valves, both the PRV and TPRV, were
correspondingly low rated. I'm not sure placing a 6 - 10 bar PRV when
an e.g. 3 bar one is required is a good idea. Also my TPRV was more
like 30 quid but I'm sure I could have paid double/triple had I gone
elsewhere.

All our flats originally came with a combined pressurised heating/hot
water system and one was leakign for months over an entranceway. One
day it was not leaking and a few weeks later the hot water tank blew up
and gutted the flat and damaged neighbouring properties. So don't
whatever you do just block up the valve!