Ariston washers, gaskets and O-rings are used in many different sections within the boiler. They are used when joining parts to the pipework of your central heating system. Heat exchangers, fans and many other parts require O-rings, washers and gaskets to prevent leaks of gas or water from occurring. Boiler spare parts must be fitted by a certified Gas Safe engineer. Orders received before 4pm are usually dispatched for next business day delivery.