"Jeff" wrote in message
...
What's this about having to fit a bypass valve to comply with building
regs?
Can't I just leave one rad without TRVs or isn't that the same?

You are not allowed to fit a normal bypass valve.
But IF your system requires a bypass it must be an automatic bypass valve.

If you have a rad without a TRV and can guarantee you won't turn it off then
you should be fine.

That said, saying leaving just one rad sounds like you only have one heating
zone which doesn't meet the building regs except in small flats. You need
at least two and each would need a rad without a TRV.