Unvented cylinder service
Annual servicing for unvented cylinders by our G3-certified engineers. We keep hot water systems safe, efficient and compliant for landlords and homeowners across the West-Midlands.
Top-rated unvented cylinder service
We check it all
We check all safety components, including pressure valves and expansion vessels, to ensure your system operates safely and meets G3 certification standards.
Peak performance
Regular servicing keeps your cylinder running efficiently, maintaining strong water pressure and reliable hot water delivery while helping to prevent breakdowns.
Health check
We inspect and test key parts like the immersion heater, thermostat, pressure gauge, and tundish to catch any early signs of wear or potential issues.
Compliance
Your service is carried out by G3-certified engineers and recorded to help maintain manufacturer warranties and meet legal safety standards, essential for landlords.
Book your unvented cylinder service
Annual servicing keeps your system efficient, compliant, and under warranty. Don’t wait for a problem, schedule your expert cylinder service today for just £90 + VAT.
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Trusted & certified G3 qualified engineers
All servicing is carried out by G3-qualified professionals with the tools and experience to keep your cylinder running safely and efficiently year after year.
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Common signs that your unvented cylinder needs a service include:
Fluctuating hot water temperature
Reduced hot water pressure
Strange noises (hissing, banging, gurgling)
Leaks or damp around the cylinder
Relief valve constantly dripping
Slow heating times
No hot water
Or if it’s been over 12 months since your last service
If you notice any of these, it’s best to book a service to keep your hot water system safe and efficient.
Unvented cylinders operate under high pressure, so a yearly service is not just good practice, it is a safety requirement.
Our thorough annual unvented cylinder service will:
Check all safety valves (T&P valve, expansion relief valve, etc.)
Test the expansion vessel / internal air gap
Verify correct pressure levels
Inspect the immersion heaters
Ensure the discharge pipework is safe and compliant
Identify early signs of limescale, leaks, or component failure
Maintain your manufacturer’s warranty (almost all brands require yearly servicing)
G3 certification refers to a specific qualification required in the UK for any engineer who installs, services, maintains, or repairs unvented hot water cylinders. Unvented cylinders operate under high pressure and store large amounts of hot water, so strict safety regulations must be followed.
A G3-certified engineer has been trained and assessed to safely work on:
Unvented hot water cylinders (e.g. Megaflo, Heatrae Sadia, Worcester Bosch, OSO)
Safety components like pressure relief valves, temperature relief valves, expansion vessels, and discharge pipework
High-pressure hot water systems
Installation and commissioning
Servicing and annual safety checks
Diagnosing and repairing faults
Legally compliant discharge pipework (G3 compliance)
Unvented cylinders store hot water under high pressure. Incorrect installation or maintenance can lead to:
Dangerous over-pressurisation
Hot water discharge
Risk of serious property damage or scalding
System failure
For these reasons, UK law states that only engineers with a G3 qualification can legally:
Install an unvented cylinder
Replace parts
Work on the safety components
Sign off or certify the system
G3 certification comes from Building Regulations Approved Document G3, which sets out the safety standards for unvented hot water systems. To stay compliant with the law, an engineer must:
Hold a valid G3 certificate
Renew or update training periodically
Follow all installation and safety standards
Ideally, yes. An annual service for an unvented cylinder is strongly recommended in the UK, but it is not a legal requirement for landlords, unlike the Gas Safety Certificate (CP12).
For homeowners:
Annual cylinder servicing is not legally required, but most manufacturers require it to keep the warranty valid.
It ensures the system remains safe, efficient, and reliable, as unvented cylinders operate under high pressure.
For landlords:
There is no specific law mandating annual cylinder servicing, but landlords are legally responsible for ensuring the system is safe.
Servicing by a G3-qualified engineer is the industry standard and helps demonstrate due diligence.
CP12 Gas Safety Certificate:
In contrast, a CP12 is legally required every year for rented properties.
It covers all gas appliances and flues and must be carried out by a Gas Safe engineer.
While a cylinder service is not required by law, a CP12 cannot substitute for it, the two are separate safety obligations.
In short:
CP12 → Legally required for rented properties
Unvented cylinder service → Not legally required, but highly recommended to maintain safety and warranty