EcoSlim Slimline Unvented Cylinder Range by World Heat.



Ultra Slim Unvented Hot Water Cylinders (400mm)


At World Heat Cylinders, we understand that modern building designs and retrofit projects often present significant space constraints. That’s why “size matters,” and our specialised Ultra Slim Unvented Cylinders are engineered to provide a high-performance hot water solution where installation space is at an absolute premium. With an exceptionally narrow profile, typically 400mm overall diameter, these stainless steel unvented cylinders are perfect for tight cupboards, compact utility rooms, apartments, and other challenging locations in both new-build and refurbishment applications.

Our Ultra Slim range delivers all the benefits of mains pressure hot water – powerful showers and fast-filling baths – without compromising on quality or efficiency, even in the most restricted spaces. We offer both plain and pre-plumbed options within this range.


Advantages of Our 400mm Ultra Slim Design


Choosing a World Heat Ultra Slim Unvented Cylinder offers several distinct advantages:

  • Space-Saving Design: With a minimal 400mm diameter, these cylinders fit where others simply cannot, unlocking valuable space.
  • Mains Pressure Performance: Enjoy high flow rates and balanced hot and cold water supplies throughout the property.
  • Versatile Application: Ideal for apartments, city dwellings, modular builds, and any installation with restricted access or limited plant room area.
  • Direct and Indirect Options: Available for all-electric heating (Direct, typically with dual immersion heaters for faster reheat) or for connection to a conventional boiler (Indirect, with a high-efficiency internal coil).
  • Stainless Steel Durability: Manufactured from high-quality Duplex stainless steel for excellent corrosion resistance and longevity.
  • High Efficiency Insulation: Featuring foam injected, zero ozone depletion potential (ODP) insulation to minimise heat loss and reduce energy consumption.
  • Pre-Plumbed Availability: Options for factory-fitted pipework and components can further reduce on-site installation time in confined spaces.


Bespoke Options for Ultra Slim Cylinders


While our standard Ultra Slim Unvented Cylinders cater to many common requirements for 400mm diameter units, we recognise that unique projects may demand further customisation. As specialist cylinder manufacturers, World Heat Cylinders can offer bespoke modifications. This includes specific tapping sizes and positions, tailored immersion heater configurations, or unique bracketry for challenging installations.

If you have a requirement for an ultra slim cylinder with non-standard features, please contact a member of our technical sales support team for further information and to discuss your project. You can reach them on 0161 343 8610 or via email at sales@whcylinders.co.uk.


Ultra Slim Cylinder Datasheets & Manuals


Download detailed technical specifications for our Ultra Slim Unvented Cylinder range:

For any specific enquiries or if you require information not listed here, please contact our technical team.

World Heat EcoSlim Unvented Cylinder in stainless steel, showcasing its slimline design.