Unvented Cylinders Guide | Greenwich Plumbing Company

By Alex Woods
As G3-qualified specialists in unvented cylinder repairs and servicing, we at Greenwich Plumbing Company often find that homeowners have questions about these essential hot water systems. Here's your comprehensive guide to understanding how they work and why proper maintenance matters.
What is an Unvented Cylinder?
An unvented cylinder is a pressurised hot water storage system that connects directly to your cold mains supply. Unlike traditional vented systems, they don't require a cold water tank in your loft, making them increasingly popular in modern South East London homes.
Benefits of Unvented Systems
Strong Water Pressure
One of the main advantages is consistent, high-pressure hot water to all your taps and showers. This means you can enjoy powerful showers without installing additional pumps.
Space Saving
Without the need for a cold water tank in your loft, unvented systems free up valuable space. This is particularly beneficial for properties in Blackheath, Greenwich, and surrounding areas where loft conversions are common.
Better Water Quality
As the system is sealed from the outside, there's less risk of contamination compared to traditional systems with open tanks in the loft.
Important Safety Features
Unvented cylinders are sophisticated systems with multiple safety features:
- Temperature relief valve
- Expansion vessel
- Pressure relief valve
- Two thermostats (working and high limit)
Each of these components plays a crucial role in maintaining safe operation, which is why annual servicing is not just recommended, it's essential.
Maintenance Requirements
As G3-qualified engineers, we emphasise the importance of:
Annual Servicing
Yearly checks should include:
- Testing all safety valves
- Checking the expansion vessel pressure
- Inspecting thermostats
- Examining the cylinder for signs of corrosion
Regular Monitoring
Keep an eye out for:
- Unusual noises
- Fluctuating water pressure
- Water discolouration
- Drips from safety valves
When to Call a Professional
Contact a G3-qualified engineer if you notice:
- Water leaking from any valve
- Unusual noises from the cylinder
- Inconsistent hot water temperature
- Loss of pressure
Installation Considerations
If you're considering an unvented system, remember:
- Installation must be carried out by G3-qualified engineers
- The system needs to comply with building regulations
- Regular maintenance is legally required
- Your home's water pressure must be sufficient
Professional Support
At Greenwich Plumbing Company, our G3-qualified team can help with:
- Annual servicing
- Maintenance
- System assessments
- Professional advice
For any unvented cylinder concerns across Blackheath, Charlton, Eltham, Middlepark, Plumstead, Thamesmead, or Woolwich, contact us.
Remember, while unvented cylinders offer excellent benefits, they require professional maintenance to operate safely and efficiently. Never attempt DIY repairs on these pressurised systems.


