I cannot immagine what anyone can do with an old design to "recondition" one. Nor can I ever think why someone would not want to buy a new part for their boiler.
Turn off the heating and let the boiler get completely cold. Run the DHW for several minutes and see if the heating flow pipe gets hot.
Tony
Turn off the heating and let the boiler get completely cold. Run the DHW for several minutes and see if the heating flow pipe gets hot.
Tony