I think you need to look a bit deeper than just the TRV's to be honest. If the system is a conventional 2 pipe layout, then closing down some rads should only increase the flow to the remainder, not stifle it. Flow should be taken from the boiler, feeding into all the rads, then the return coming from all rads, back to the boiler, with a bypass of some description fitted to ensure flow through the boiler at all times. If rads are getting cold when others are turned down, that would suggest that some rads are receiving their flow after its already been through other rads.
Difficult to say further without a better insight into how it's been plumbed, but if heating system was renewed/refurbed as part of the previous owners 'upgrade' then anything is potentially possible.
Difficult to say further without a better insight into how it's been plumbed, but if heating system was renewed/refurbed as part of the previous owners 'upgrade' then anything is potentially possible.
