Thanks for this, it’s making sense now.The ones that are looped are a 22mm and a 15mm. Same as mine. 15mm mains cold feed to the tanks in loft, 22mm for the gravity feed from cold tank to taps and immersion Cylinder.
Presumably if you’ve converted from conventional to combi, the 22mm will now be the cold feed to the boiler.
The combi boiler is fed via a 15mm that I can see coming straight off the main at the stopcock, which is on the opposite side of the room to this.
What’s bizarre is that on another thread I posted, the bath is fed by both a hot and a cold 22mm pipe that emerge from the floor, so they must go from 15 to 22 somewhere within the wall or the concrete floor, because I can’t see it anywhere!