I need to drain off CH system to replace rad, my installation book for the Vaillant thermocompact boiler says "system to be filled via seperate filling point fitted at convenient point on the heating circuit. The connection must be removed when filling complete".
My question is, what am I looking for? as there is no likely looking connection device that I can see.
There is what appears to be a pressure relive valve on the supply to the HW cylinder, would this be it?
Would be grateful for some guidance.