I'm attempting to confirm which of the two pipes of my central heating spur is the flow and which is the return.
The advice I've found so far says to look for marking: RED marking (either tape or valve handle or something else) etc show it to be flow, BLUE/no marking for return. Or run the heating and the FLOW pipe will get hot first.
However, I have a pair of pipes which are a spur off my heating loop, which are put in place to connect to my under floor heating. Neither of them have any water flowing in them at the moment (so neither get hot), as the heating has not been fully installed. How do I make sure I connect the flow to the correct side of my under floor heating pump?