Service identification on central heating circuit. Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[m7ohn]

I've bought a house where the back boiler has been removed and i have capped pipes.
How can i identify which of the 22mm pipes are the central heating out and return? There is no filler loop or expansion tank only that one of the pipes has a low point drain on.

Thanks

Marcus

[wishiwascorgi]

Hi marcus, i have found on back boilers that the flow and return come from one side and that the flow is at the top. If you have 2 pipes on each side then one side is usually for the hot water cylinder. Best thing to do is pull the floorboards up above the boiler upstairs.

[m7ohn]

Thank you for the reply, i have found out which two pipes are flow and return but which way round are they.How do you identify which does the flow and which one does the return?Does the flow pipe go to the radiator thermostatic valves first then returns via the other side through the non thermostatic valve?

Thanks

[wishiwascorgi]

on older trv's they were put them on the flow but now trvs are bi directional so they can be on the flow or the return. Have a look for a pump on the pipe work near to where your old boiler was and that would be on the return.

[wishiwascorgi]

sorry for the delay in my reply i was on holiday

[m7ohn]

Hope you had a nice holiday.

The pump and associated pipework have been removed so cannot make out which line the pump was on but on each rad is a TRV with an arrow indicating the direction of the flow, these look like the old type of Honeywell valve so i'm guessing they're not bi-directional?