HVAC Questions? Ask an HVAC Expert for Answers ASAP
Take a photo to your nearest traditional plumbers' merchant, and they should sort you out. B&Q also have some vent plugs. If nobody can help you from a photo, then shut both of the radiator valves and remove the drain plug.Before you fit the new one, remove all sharp edges of paint and metal burrs from the hole. Then smear the sealing O ring of the vent plug with some silicone grease.