HR92 controlled Rads not triggering Boiler

[DMW]

Hi - i have a recently installed evohome system with a number of UFH zones and some radiator zones.
the UFH is divided into 4 zones and each other room has a radiator in which is governed by a HR92.

Everything works fine as long as the UFH is on.

If the UFH goes off (for example if it is very sunny in the kitchen/diner area and temp exceeds setting) then the radiators do not work.
When there is no UFH the radiators are not triggering any reaction/response in the boiler relay - i.e. the green light does not come on.

All radiators are showing as bound and as initially stated, everything works fine if UFH is on, i can control radiators as i like.

Can anyone give me any advice as to what i need to do to enable the heating to work if there is no UFH requirement?
the boiler being used is a baxi combi.

thanks in advance for any ideas...

[Richard]

Sounds like you haven't quite understood the evohome system hierarchy.

When you are mixing technology with evohome (radiator controllers, single zones and UFH) there is a specific way you must have your system designed and evohome setup to ensure it works.

Who fitted your system? What design was followed?