I have recently switched all my TRVs to HR92s; I also swapped out my hive relay/controller for a BDR91 and it was easy as that - evohomed!

FYI, I have a Worcester Greenstar 30si, and I have decommissioned a Hive system (with dumb TRVs) to install the above kit. But the main radiator (which was in the same room as the hive thermostat, and didn't have a TRV) was almost always on, as long as any one of the other radiators was on.

So: I thought I was being clever by adding a TRV valve to the main radiator (I did this by simply de-pressurising the system using a bleed valve, using pipe-freezing spray, etc.).

However, I started to think about it, and I got worried... What happens if all the TRVs are off (at 0%), and (due to sync delay) the boiler is still providing/pumping to the CH? Is it pumping against a closed system? If so, can I damage my system?

For now, I have put a TRV on a small radiator at set it to 5/5... But do I need to call a plumber and put in some plumbing to cope with the above scenario?