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Is your Hot Water Cylinder up in the roof space cavity?

Is your hot water cylinder situated in the roof cavity? What a chaotic situation! Not only is access restricted, but without any anti-flood measures like a cylinder tray, the combination of water and gravity could pose serious issues.

Challenges will depend on the type of hot water system you have.

System designs may include:


  1. Low pressure hot water cylinder which may have an open vent penetrating the roof.
  2. Mains Pressure Hot water cylinder which may not have a tray but a drain for the safety valves.
  3. Just a header Tank supplying a low pressure system on a different level.
  4. A gas instant water header which will have a flu penetrating the roof.
  5. Accessible incentives and rebates.

Is your Hot Water Cylinder up in the roof space cavity? If it is, you’re certainly not alone. Many homes have their hot water cylinders installed in the roof cavity for various reasons, including space-saving and convenience. However, while this placement can be practical, it also comes with its fair share of challenges and potential issues that homeowners should be aware of. In this blog, we’ll explore the challenges of having hot water cylinders in roof spaces and discuss some solutions and alternatives.

Challenges of Hot Water Cylinders in Roof Spaces:


  1. Limited Access: One of the most significant challenges of having a hot water cylinder in the roof space is limited accessibility. Roof spaces are typically cramped, dark, and difficult to navigate. This makes routine maintenance and repairs more challenging and may require professional assistance.
  2. Risk of Flooding: Without proper anti-flood measures, the combination of water and gravity can pose serious issues. If your hot water cylinder were to develop a leak or burst, the water could flow freely into your home, causing extensive damage to ceilings, walls, and belongings.
  3. System Variations: The specific challenges you face will depend on the type of hot water system you have. Here are some common system designs and their associated challenges:
    • Low-Pressure Hot Water Cylinder: This type of system may have an open vent that penetrates the roof. While this vent helps relieve pressure, it can also be a potential entry point for pests and debris.
    • Mains Pressure Hot Water Cylinder: These cylinders may not have a tray, but they typically have a drain for safety valves. However, if this drain becomes blocked or damaged, it can lead to flooding issues.
    • Header Tank Supplying a Low-Pressure System: In this scenario, you may have a header tank in the roof space supplying a low-pressure hot water system on a different level. Maintaining the correct water levels in the header tank can be challenging.
    • Gas Instant Water Heater: Gas instant water heaters often have a flue penetrating the roof. These need regular maintenance to ensure proper ventilation and safety.

Solutions and Alternatives:

  1. Install a Cylinder Tray: To address the risk of flooding, consider installing a cylinder tray under your hot water cylinder. A cylinder tray installation collects any leaked water and directs it away from your home, preventing damage. You can find more information about cylinder trays on
  2. Regular Maintenance: Regardless of the type of hot water system you have, regular maintenance is essential. This includes checking for leaks, ensuring safety valves are functioning correctly, and inspecting vents and flues for blockages. A professional plumber can assist with these tasks. This will make sure that a) your water is safe and clean b) your power bill does not increase due to inefficiencies.
  3. Consider Relocation: If the challenges of having a hot water cylinder in the roof space become too cumbersome, you might consider relocating it to a more accessible location, such as a dedicated utility room or garage. This can make maintenance and repairs easier.
  4. Explore Alternative Water Heating Systems: Depending on your needs and budget, you could explore alternative water heating systems that don’t require placement in the roof space. Tankless water heaters, heat pump water heaters, and solar water heaters are options worth considering.
    In conclusion, having a hot water cylinder in the roof space cavity can present challenges related to access and the risk of flooding. However, with the right precautions and regular maintenance, these challenges can be managed effectively. Additionally, exploring alternative water heating systems or relocating your hot water cylinder may be viable solutions to address these issues. To learn more about cylinder trays and other solutions, visit for expert advice and products tailored to your needs.