Unvented cylinder
servicing.
An annual check of your unvented hot water cylinder’s safety devices by a qualified engineer – needed to keep most manufacturer warranties valid.
Why service an unvented cylinder?
An unvented cylinder holds hot water under mains pressure. Its safety valves, expansion vessel and controls stop the pressure and temperature getting too high, so they need checking regularly.
Manufacturers such as Megaflo and Gledhill ask for an annual service by a competent person to keep the cylinder’s warranty valid. Keep the service record with your cylinder paperwork.
What the service usually covers
- Checking the pressure reducing valve and the incoming pressure
- Checking and recharging the expansion vessel
- Testing the temperature and pressure relief valve and expansion relief valve
- Checking the tundish and discharge pipe are clear and correctly routed
- Checking the thermostats, immersion heater and controls
- Looking for leaks and corrosion, and recording the results
Any parts needed are explained and priced before they are fitted.
Signs it needs attention now
- Water dripping from the discharge pipe outside or into the tundish
- Hot water pressure dropping or surging
- Banging or noisy pipes when hot water runs
- No hot water, or water that is too hot
If you see any of these, arrange a repair rather than waiting for the service.
Send these details when booking
- Cylinder make, model and size (on the label on the cylinder)
- Whether it is heated by your boiler or electric only
- The date of the last service, if known
- Photos of the cylinder, valves and tundish
- Full postcode, access and parking arrangements
Servicing questions
Can my boiler engineer service the cylinder?
Only if they are qualified for unvented hot water systems. Many engineers service both at the same visit – ask when booking.
How often should it be serviced?
Once a year, unless the manufacturer’s instructions say otherwise.
Landlord?
An annual cylinder service is good practice and is often required by the manufacturer’s warranty. It is separate from the gas safety certificate.
Who does the work
Work is carried out by one of our approved installation partners, registered for the work involved. Your written quotation names the installer, who your contract is with, and your warranty and workmanship guarantee.