We had our bungalow repiped with new rads throughout. UFH was also installed in our new extension. the installation guys put everything on 1 zone using an 8kw heat pump to power everything. when the rads call for heat we get them nice and toasty. when the UFH is on the extension gets nice and toasty. when both are on we don’t get any heat to the rads but the UFH stays running as it should. the installers didn’t fit the pump / blender that came with the UFH system either. Does anybody have any idea why this is happening? They both work fine on their own but just not together. the UFH company say they should have been separated in separate zones but installers say 1 zone is what they usually do. slab was down 7/8 weeks ago and UFH has been on for last 6 weeks so everything should be dry etc. Any ideas welcome, it’s driving us nuts.