DIY Doctor UK DIY Forums

am i right in saying, on a double pipe heating system, the main feed and return pipes are 22mm, and teeing off to radiators, feed and return pipes are 15mm. ..........and if i added another rad i tee into the 22mm feed and 22mm return.....with 15mm speedfit , would that be ok ??? Thanks

My feed and return are 15mm under the floor boards but 22mm from boiler and primaries and thus are reduced somewhere after the motorised valve.

Lift a floorboard and take a look.