Before
Cylinder cupboard before the finished pipework example.
Unvented Cylinder Plumbing in Essex
Unvented hot water cylinders deliver strong mains-pressure hot water, but they include safety devices that must be installed and maintained correctly.
REZ Heating & Plumbing Services is G3 qualified and provides unvented cylinder servicing, fault investigation, component replacement and cylinder plumbing across Colchester, Essex and Suffolk.
Helpful guidance
How an unvented cylinder works
Unlike a traditional vented cylinder, an unvented cylinder is supplied directly from the mains and does not rely on a cold water storage tank for hot-water pressure.
The system normally includes:
- Pressure-reducing controls
- Expansion control
- Temperature and pressure relief protection
- Discharge pipework
- Thermostats and immersion heaters
- An expansion vessel or internal air gap, depending on the model
These components work together to control pressure, temperature and expansion.
Common unvented cylinder faults
Typical problems include:
- No hot water
- Water that is too hot
- Discharge from the tundish
- Loss of pressure
- An expansion vessel that has lost charge
- A failed immersion thermostat
- A pressure-reducing valve fault
- A relief valve that does not reseat
- Noisy operation
- Electrical heating problems
Water passing through the tundish should not be ignored. It is a visible warning that a safety or control device may be operating.
Expansion vessels
When water heats, it expands. The expansion vessel absorbs this increase in volume.
If the vessel loses its air charge or the diaphragm fails, pressure can rise and water may discharge through the safety valves. Recharging may be suitable in some cases. A damaged vessel requires replacement.
Servicing
A service normally includes checks appropriate to the installation, such as:
- Visual inspection of the cylinder and controls
- Expansion provision
- Safety valve operation
- Tundish and discharge arrangement
- Thermostat and temperature control
- Evidence of leaks or corrosion
- General installation condition
Servicing cannot guarantee that a component will never fail, but it can identify obvious issues and help maintain safe operation.
Real work examples
Recent unvented cylinder projects
These are genuine examples of completed unvented cylinder work carried out by REZ Heating & Plumbing Services across Colchester, Essex and Suffolk.
Before, during, after
Clear project stages
Before and after examples are shown only where the project photos clearly support a fair comparison.
After
Visible cylinder pipework after the work.
Before
Area before the compact heater project.
After
Compact heater installed with visible pipework.
Related services
Related plumbing services
These related services can help if your plumbing issue involves more than one part of the system.
FAQs
Questions customers often ask before booking
Do I need a G3-qualified plumber?
Work involving the installation or safety controls of an unvented cylinder should be carried out by someone with the appropriate G3 qualification.
Why is water dripping through the tundish?
A safety or control valve may be discharging because of pressure, expansion or a component fault. The cause should be investigated.
How often should an unvented cylinder be serviced?
Annual servicing is commonly recommended by manufacturers, but the exact requirements should be checked for the specific cylinder.
Can an unvented cylinder be repaired?
Many faults can be repaired by replacing or servicing the relevant component. Replacement is not always necessary.
Ask Rez for practical advice
Need help with an unvented cylinder?
Send a clear photo of the cylinder label, controls, tundish, expansion vessel and any visible discharge or error information.
Call, WhatsApp photos or request a quote when you are ready.