Water tank repair in KT21 (30)

If your hot water is running out quickly, your pressure is dropping, or your cylinder isn’t heating properly, it’s time to find a G3-qualified tradesperson for assistance.

Search for unvented hot water cylinder servicing or repair in KT21 with Checkatrade — they can check safety devices, diagnose faults, and restore your system to full performance.

What is unvented hot water cylinder servicing?

Unvented hot water cylinder servicing involves inspecting and testing all safety components, valves, and heating elements to ensure the cylinder is working efficiently and safely.

Unlike standard cylinders, unvented systems store water at high pressure, so regular servicing is essential to prevent faults and maintain performance.

Signs you might need unvented cylinder servicing or repair

• Hot water running out faster than normal
• No hot water at all
• Low pressure at taps or showers
• Leaking pipework, valves, or discharge pipe
• Cylinder making unusual noises
• Temperature fluctuations or slow reheat times
• Visible corrosion or dripping around the tundish

How much does unvented cylinder servicing or repair cost?

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Bear in mind, several factors can affect the cost of unvented cylinder servicing or repairs:

• Type of repair (valves, thermostat, immersion heater, expansion vessel)
• Availability of replacement parts
• Cylinder age and manufacturer
• Whether a fault is discovered during servicing
• Time needed for diagnostics or draining

Many engineers also offer annual service packages, which often reduce one-off callout fees.

Our unvented hot water cylinder cost guide has more detailed information.

Common unvented cylinder faults

• No hot water: Faulty immersion heater or thermostat
• Low pressure: Expansion vessel issues or pressure relief valve problems
• Water leaking: Loose joints, corroded pipework, or faulty relief valves
• Frequent discharge from tundish: Pressure or temperature issues
• Unusual noises: Limescale build-up or trapped air
• Slow reheat: Failing heating element or thermostat

A G3-qualified engineer can diagnose the issue safely and recommend repair or replacement parts.

Unvented cylinder servicing vs repair

Choose servicing when:

• It has been 12 months since the last check
• Safety valves need testing
• You want to maintain your manufacturer warranty
• You want to prevent faults before they occur

Choose repair when:

• The system has a clear fault (no hot water, leaks, pressure issues)
• A component has failed (valve, immersion heater, expansion vessel)
• The cylinder is making noises or discharging frequently

Regular servicing reduces the likelihood of costly repairs.

How often should an unvented hot water cylinder be serviced?

Unvented cylinders should be serviced once a year to check all safety devices, pressure levels, and electrical components.

Annual servicing is required to keep the system running safely and may be needed to maintain warranty validity.

How long does servicing or repair take?

• Servicing: Usually 30–60 minutes
• Repairs: Typically 1–2 hours, depending on the part being replaced

Complex faults or immersion heater replacements may take longer, especially if the cylinder needs draining.

How long does an unvented hot water cylinder last?

Most unvented cylinders last 10–20 years, depending on water quality, usage, and how consistently the system is serviced.

Components such as valves and immersion heaters may need periodic replacement during the cylinder’s lifespan.

Maintenance of unvented hot water cylinders

• Book annual servicing with a G3-qualified engineer
• Check for dripping around the tundish
• Keep the area around the cylinder clear for ventilation
• Address leaks or pressure issues immediately
• Avoid tampering with safety valves (high-pressure systems can be dangerous)

What should be included in your quote for unvented cylinder servicing or repairs?

When comparing quotes for unvented cylinder servicing or repair in KT21, check that they include:

• Full inspection and testing of safety valves
• Breakdown of labour and parts
• Diagnostics and fault identification
• Replacement components (if needed)
• Callout charges or emergency rates
• Warranty on parts and workmanship
• Estimated repair timescale

Clear quotes help you compare service quality and avoid unexpected extra costs.

Common mistakes to avoid with an unvented hot water cylinder system

• Skipping annual servicing
• Attempting DIY repairs on high-pressure systems
• Ignoring dripping from the tundish
• Using non-approved replacement parts
• Delaying repairs when water temperature or pressure changes

Tips for hiring an unvented cylinder engineer in your area

Before hiring an engineer to service/ repair your unvented hot water cylinder:

• Check reviews on Checkatrade
• Confirm the engineer holds a valid G3 unvented cylinder qualification
• Ask what checks are included in the service
• Compare quotes for parts, callout fees, and labour
• Request advice on long-term maintenance or recurring issues

For checked trades committed to quality and a job done right, search for unvented hot water cylinder servicing or repair in KT21 with Checkatrade.