Never serviced my hot water cylinder. What needs to be maintained?

I’d recommend getting your hot water cylinder a service every year to ensure its working efficiently, some of the checks include a visual inspection of pipes and joints, safety components, check thermostat, hot water temperature, expansion vessel , flow rate to the taps, if your cylinder jacket needs replaced, note there is different types of hot water cylinders depending on the system you have but above is the things that you would be looking for, hope this helps

It depends if your cylinder is vented or unvented and if UV then which manufacturer/model. For example, if you have a Megaflo unvented cylinder then the expansion bubble should be regenerated every 12 months which can be done by the user. Anything else on a UV needs someone with G3 competence to address.

I’d recommend servicing every years to prevent any problems arising Check all pipework Check expansion vessel is operating correctly Check pressure relief valve is operating correctly These are the 2 important components

If the cylinder is unvented you are not allowed to do DIY work on it . You have to be qualified to complete any work on it . If it's just an ordinary vented one you can work on any part as it won't explode.