Acv oil combined hit water and heating

[Inverness]

hi guys, anyone experienced acv boiler?
Went to one today and the blending valve that's comes off it is leaking so I'm needing to replace it. there's a secondary bronze pump linking into it and a cold main so this must be linked for the hot water? But why would there be a tmv on the hot outlet?
In less it's for the underfloor heating?
I'll need to have a proper look and look at the manual. But underfloor heating manifolds have there own incorporate blending valves on the manifold.