Intergas Xtreme combi with rads, UFH and evohome Opentherm

[Richard]

Thanks, that makes sense.

And in terms of controls; I’m thinking through - how would the secondary pump be activated when using an opentherm gateway? I know I’d drive the UFH pump from the HCC80 pump output, but not sure how to drive the rads secondary pump when any radiator is calling for heat?

[edit] doing some reading and thinking; I am guessing what I use is the opentherm gateway on the boiler, then a BDR91 run in a zone valve configuration to open a valve and run the pump from the switch contacts in the valve?

With evohome we can setup a BDR91 as a 'heating valve actuator' which can be linked to the secondary pump.