this is fully pumped w plan i think. 3rd pipe rises vetically outside chimney breast & gets warmish not hot when boiler runs. connects to one of 2 top tappings on bbu hex
tom, June 2011
hot water flow, heating flow and heating/hot water return. the will be a tee close by that you can not see.
erj, June 2011
Could be primary flow and domestic return and heating return
