What maintenance do unvented cylinders require?
What maintenance do unvented cylinders require? – while there is no strict legal mandate for an annual service for a standard unvented cylinder (unlike a gas boiler), regular maintenance is absolutely critical for safety, compliance, and warranty purposes.
Under Building Regulations Part G, an unvented system must be maintained in accordance with the manufacturer’s instructions. Therefore, to remain compliant and keep your manufacturer’s warranty valid (which often spans up to 25 years), you should have the cylinder serviced annually by a G3-qualified heating engineer.
During a professional annual service, the engineer will typically perform the following tasks:
- Inspect the vessel and pipework: Checking for signs of leaks, corrosion, or physical damage.
- Test safety valves: This is the most critical step. They will test the Temperature and Pressure (T&P) relief valve to ensure it operates correctly, preventing dangerous over-pressurisation.
- Check the expansion vessel: Ensure the expansion vessel (internal or external) is holding the correct air pressure to accommodate the expanding water.
- Verify settings: Checking that the operating temperature and pressure are within safe limits.
- Inspect the discharge pipe: Ensuring the external tundish and discharge pipe are clear of blockages or frost.
Homeowner Maintenance
Between professional services, you should perform simple visual checks. Look out for dripping from the tundish (the small plastic funnel usually near the cylinder), which indicates a safety valve has lifted. Ensure the external discharge pipe isn’t blocked by debris or frozen in winter and listen for unusual noises like excessive rumbling.
In summary, while the law doesn’t explicitly force an annual service, failing to maintain the cylinder according to the manufacturer’s instructions voids your warranty and compromises the vital safety devices that prevent catastrophic failure.
