Hot Water Systems

Unvented Cylinder Installation

Unvented cylinder installation gives you strong, consistent mains-pressure hot water without relying on a loft tank. It is a practical upgrade for better showers, faster bath fills, and reliable hot water delivery, provided the system is designed, installed and commissioned with the correct safety controls.

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What unvented cylinder installation covers

A complete supply and fit service, focused on safe performance and dependable hot water.

  • Assessing your hot water demand, incoming mains pressure and available space
  • Helping you choose the right cylinder size and specification for your property
  • Installing the cylinder and connecting hot, cold and primary (if applicable) pipework
  • Fitting required safety components such as pressure reducing valve, expansion control and temperature and pressure relief protection
  • Correctly installing tundish and discharge pipework to current requirements
  • Commissioning, testing and setting the system up for safe operation
  • Clear handover on how the controls work and what to monitor

When this service is the right fit

Unvented cylinders suit properties that need better flow and pressure at multiple taps.

  • Low pressure hot water from a gravity-fed cylinder
  • Multiple bathrooms or busy household hot water demand
  • Renovations, extensions and bathroom upgrades
  • Landlord replacements where compliance and reliability are priorities
  • Small commercial premises needing consistent hot water delivery

How installation works

Work typically starts with checks on mains pressure and flow, then confirming the cylinder location, pipe routes and safety discharge route. The old cylinder is isolated and removed where applicable, then the new unit and safety kit are installed, connected and insulated as required. Finally, the system is filled, tested and commissioned so pressures, temperatures and safety devices operate correctly.

After installation: ongoing value and support

You will get guidance on normal operating pressures, what the tundish is for, and what signs suggest a fault. If you book periodic servicing, key safety devices can be checked and the system kept running efficiently. If performance drops, fault diagnosis can usually be targeted quickly because the installation has been set up and tested properly.

Frequently Asked Questions

Do I need a certified engineer for an unvented cylinder?
Yes. Unvented cylinders must be installed and commissioned by an engineer with the correct unvented hot water qualification (often referred to as G3). This is essential for safety devices, correct discharge pipework, and compliance.
How long does an unvented cylinder installation take?
Many straightforward replacements can be completed within a day, but this depends on access, pipework changes, and whether upgrades are needed for valves or discharge routing. You will be advised of the expected timescale after an on-site assessment.
What size unvented cylinder do I need?
Sizing depends on the number of bathrooms, household occupancy, and hot water usage patterns. Incoming mains flow rate and pressure also matter, as they affect how quickly the cylinder can recover. A quick assessment helps avoid undersizing or paying for capacity you will not use.
Can you remove and dispose of the old cylinder?
In most cases, yes. The existing system is isolated, drained and removed safely before the new cylinder is installed. Disposal can be arranged as part of the job if required.
Will the installation meet Building Regulations requirements?
It should, provided it is designed and installed correctly with the required safety components and compliant discharge pipework. You should also expect proper commissioning and documentation for the installation. Ask what paperwork will be provided for your specific setup.

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