Plumbing rat's nest surrounding boiler.
Rightmost vertical 1/2" Cu line that runs horizontally to the left, then up into the green handled ball valve is hot water out; green ball valve feeds hot water to entire house. Longer vertical Cu line next to it that turns through two elbows into blue handled gate valve then to tee is cold supply to domestic heating coil. The other blue handled gate valve below the tee is the boiler make up water feed; it passes through a backflow preventer then two elbows, through fill regulator and another valve, then into heating circuit return line. 1" Cu line with blue handled ball valve in foreground is heating loop outlet line; it is reconfigured later in the process.