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Combination Cylinders
Bespoke Combination Cylinders: Hot Water + Cold Storage Combined
- Incorporates built-in cold water storage (feed tank)
- Available to a bespoke specification for connection positioning and sizes
- Ideal solution for limited (or none) loft space
Combination Cylinders (also known as a Combi Cylinder) are designed as a space-saving unit by incorporating a built-in cold water storage tank at the top of the unit. This removes the need for a separate header tank, which is useful where there is little to no loft space. The external tank is pre-installed on the unit and connected with feed pipes reducing installation time.
As with many of our other units, we can manufacture a combination cylinder to a bespoke specification, allowing for the positioning of connections, connection sizes as well as additional heat sources such as solar, boiler and heat pump.
Although the unit sacrifices hot water storage volume for cold water storage volume, we can manufacture up to 600mm in diameter combination cylinders. This allows for a hot water storage volume sufficient for most domestic properties.
Direct and Indirect Combination Cylinders
We manufacture combination cylinders in both configurations, each suited to different heating systems.
Direct Combination Cylinders
Direct combination cylinder models rely on electric immersion heaters to heat water in the cylinder that is supplied from the cold water storage. They are ideal for properties with electric-only heating systems, Economy 7 tariffs, or where boiler installation isn’t practical.
Indirect Combination Cylinders
For indirect combination cylinders, water is heated through a coil (or multiple coils) connected to a heat source such as a boiler. While an immersion heater provides backup support. The cold water storage feeds both the attached cylinder and cold water outlets throughout the building.
Indirect combination cylinders are compatible with gas boilers, oil boilers, heat pumps, and solar thermal systems.
Size Guides
DIRECT COMBI SIZE GUIDE
| Size | Hot | Cold |
|---|---|---|
| 900×400 | 67 Litres | 16 Litres |
| 1050×400 | 91 Litres | 16 Litres |
| 1200×400 | 91 Litres | 32 Litres |
| 1500×400 | 114 Litres | 32 Litres |
| 1800×400 | 166 Litres | 32 Litres |
| 2000×400 | 210 Litres | 32 Litres |
| 900×450 | 85 Litres | 20 Litres |
| 1050×450 | 115 Litres | 20 Litres |
| 1200×450 | 115 Litres | 40 Litres |
| 1500×450 | 160 Litres | 40 Litres |
| 1800×450 | 210 Litres | 40 Litres |
| 2000×450 | 250 Litres | 40 Litres |
| 1500×500 | 180 Litres | 60 Litres |
| 1800×500 | 240 Litres | 60 Litres |
| 2000×500 | 260 Litres | 60 Litres |
| 1500×600 | 280 Litres | 80 Litres |
| 1800×600 | 320 Litres | 80 Litres |
| 2000×600 | 360 Litres | 80 Litres |
INDIRECT COMBI SIZE GUIDE
| Size | Hot | Cold |
|---|---|---|
| 900×400 | 67 Litres | 16 Litres |
| 1050×400 | 91 Litres | 16 Litres |
| 1200×400 | 91 Litres | 32 Litres |
| 1500×400 | 114 Litres | 32 Litres |
| 1800×400 | 166 Litres | 32 Litres |
| 2000×400 | 210 Litres | 32 Litres |
| 900×450 | 85 Litres | 20 Litres |
| 1050×450 | 115 Litres | 20 Litres |
| 1200×450 | 115 Litres | 40 Litres |
| 1500×450 | 160 Litres | 40 Litres |
| 1800×450 | 210 Litres | 40 Litres |
| 2000×450 | 250 Litres | 40 Litres |
| 1500×500 | 180 Litres | 60 Litres |
| 1800×500 | 240 Litres | 60 Litres |
| 2000×500 | 260 Litres | 60 Litres |
| 1500×600 | 280 Litres | 80 Litres |
| 1800×600 | 320 Litres | 80 Litres |
| 2000×600 | 360 Litres | 80 Litres |
Example Specification
Direct Combination Cylinder Specification
- 50mm Insulation
- 3/4″ Hot Draw Off
- 2 1/4″ Bottom Entry Immersion Heater Boss
- 1/2″ Drain
- Ball Valve & Float
- Aluminium Lid with Rolled Safety Edge.
Indirect Combination Cylinder Specification
- 50mm Insulation
- Boiler Coil with 3/4″ Male Connections
- 1″ Female Direct Connections
- 3/4″ Hot Draw Off
- 2 ¼″ Bottom Entry Immersion Heater Boss
- 1/2″ Drain
- Aluminium Lid with Rolled Safety Edge.
When to Choose a Combination Cylinder:
Limited or Loft Access
If a property doesn’t have suitable space for a traditional header tank, homeowners can benefit from an integrated cold water storage. This sits directly above the hot water cylinder, eliminating the need for loft access.
Simplified Installation and Reduced Labour
Due to the combination of cold water storage and a hot water cylinder, the installation of a combi cylinder is faster than running pipework between a header tank and acylinder. It also minimises the number of connections and lowers the risk of installation errors.
New Builds and Renovations
Architects and developers utilise combination cylinders for new builds. This enables home designers to maximise the usable loft space.
How does a direct combination (or ‘combi’) cylinder work?
Like a standard vented system, a combination cylinder relies on gravity to supply hot water (potable) to a building’s outlets. The cold water cylinder (or tank) is located directly above the hot water tank. As a result of this, the generated ‘head’ of water pressure is relatively low.
What is an indirect combi cylinder?
An indirect combi cylinder, also known as an indirect cylinder or tank, utilizes an internal coil connected to a boiler or central heating system. This internal coil acts as the primary heat source to heat the water stored in the cylinder. In case of any issues with the primary heating system, there is a backup immersion heater available for heating purposes.
What is a fortic cylinder?
A fortic cylinder is an alternative name for a combi cylinder.
Do combination cylinders require more floor space than standard cylinders?
No additional floor space is required. Combination cylinders have the same diameter as standard cylinders (we manufacture up to 600mm diameter), but are taller to accommodate the cold water storage section above the hot water cylinder. The footprint in your airing cupboard remains identical.
Can I use a combination cylinder with a heat pump?
Yes, we manufacture indirect combination cylinders with large surface area coils specifically designed for low-temperature heat pump systems. The integrated cold water storage works perfectly with heat pump installations, and we can accommodate dual coils if you want to add solar thermal in future.