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Gas Appliance Guide

AGA hot water cylinders


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AGA hot water cylinders

AGA stove logo  Rayburn stove logo

Hot water copper cylinders for use with an AGA or unpumped heat source

Index Page > Hot Water Cylinders > AGA Hot water cylinders

Domestic hot water cylinders to be used with an unpumped heat source

Hot water from AGA and Rayburn stoves

AGA, Rayburn, Wood Burning Stoves

Hot water cylinders for use with a wood burning or multifuel stove


Gravity boiler coil - large bore heat exchanger suitable for an unpumped heat source

An 'indirect' cylinder is designed to be heated by a remote heat source. The typical modern gas boiler produces a pumped circuit of hot water that will heat both cylinder and radiators. There are however devices that can produce a circuit of hot water that is unpumped, relying instead on 'thermo-siphoning' or 'gravity circulation' to move the water around the system. It is important to match the type of cylinder to the heat source - pumped (as it would be from a typical modern boiler) or unpumped (the sort of heat source one might expect to get from a solid fuel or wood burning stove, an AGA or Rayburn stove). The cylinder should also be a vented type*.

* Note: Unvented cylinders (the pressurised type that provide mains pressure hot water - e.g. Megaflo, Stainless Lite) should not be connected to a heat source that cannot be fully controlled - the risk of explosion exists. Mains pressure hot water can however be achieved in conjunction with a gravity heat source by using a device such as a Thermal Store.

For more info please click on the links or feel free to contact our office and we will be more than happy to explain.

How an AGA cylinder differs

An AGA (for example) may produce an 'unpumped' circuit of hot water relying on the principle of 'thermosiphoning' (hot water rising and cooler water falling) to create 'gravity circulation' within the system. A cylinder that will happily accept an unpumped heat source is subtly different from a standard cylinder in so far as the heat exchanger has a larger diameter bore (28mm) and bigger connections (to accommodate larger flow and return pipework). Connections may be spaced slightly further apart improving the thermal dynamics and therefore the flow.

Choose the correct cylinder for AGA, Rayburn and Wood burning stoves

Do not connect a cylinder designed for a fully pumped system to an unpumped system. The smaller bore pipework and heat exchanger in a cylinder suitable only for a pumped system would create a bottleneck and constrict the flow of a gravity system. The strangled flow could have significant implications for heat transfer dissipation. Please ensure you mention the heat source/s you intend to connect when ordering to ensure you get the right advice and the correct product.

A vented 'gravity' cylinder has a larger bore boiler coil for unpumped heat source flow

A remote heat source with a Direct connection

Although unusual these days, there are systems that have a remote heat source that directly heats the water. This is to say the water in the cylinder travels to the heat source, is heated, then travels back to the cylinder. This is a traditional type of 'direct' system which requires no heat exchanger in the cylinder (only direct tappings). For this to work without contaminating the water the heat exchange process must take place in a non-ferrous heat exchanger at the boiler end. Such a heat exchanger might be ceramic or made of copper. If your cylinder requirement is for this type of system please call.

  • 28mm big bore boiler coil gives better gravity flow and more efficient heat exchange

  • 28mm boiler connections  facilitating larger flow and return pipework

  • 22mm connections

    for cold water 'feed' and hot water 'out' (This may be altered if required)

  • Tappings to suit

    You can specify position of connections if required (Sketch recommended)

  • Immersion Heater side or top

    Top or side mounted immersion heater boss if and as required (please state)

  • Fully Insulated

    All cylinders are supplied insulated and fully compliant with Part L.

  • Please note, the thickness of insulation (*allow nominal 50mm on either side) whilst included is not stated in the dimensions. Please ensure the cylinder will fit the space you have available.

(Example: 450 stated diameter + 50mm either side (2x50) = 550mm finished diameter)

  • Additional Connections

    You can customise your cylinder by adding optional features such as a dedicated 'Shower take-off' or a 'secondary return' . Please make this known before concluding your purchase.

INDIRECT Copper Cylinders for use with AGA, Rayburn, Wood Burners and unpumped (gravity flow) indirect heat sources

Systems that generate a a gravity heat source are often deemed 'uncontrollable' as they cannot be turned up/down or on/off as required (For example: Wood burning stoves). With this type of heat source provision should be made to 'bypass', 'dump' or 'leak' heat away from the cylinder or the heat source to prevent the risk of overheating, boiling or evaporation. One way to achieve this is by utilising a bypass valve and heat leak radiator.

In general, but only as a rule of thumb, it is considered that an 'entry level' cylinder in such a system should contain in the region of 140 litres of water as a minimum. This figure may differ according to your hardware. Please refer to your system specification or stove manufacturer before placing an order.

Size and Price list

Open vented cylinder with large bore heat exchanger for use with gravity flow heat source


Please note, the thickness of insulation (*allow 50mm on either side) whilst included is not stated in the dimensions. Please ensure the cylinder will fit the space you have available.

Rayburn & AGA stoves


Size (mm)

Nominal Capacity

Imperial Size Equiv

inc VAT

1200 x 400


48 x 16


1500 x 400


60 x 16


1050 x 450


42 x 18


1200 x 450


48 x 18


1500 x 450


60 x 18


1800 x 450


72 x 18


1200 x 500


48 x 20


1270 x 500


50 x 20


1500 x 500


60 x 20


1800 x 500


72 x 20


1200 x 600


48 x 24


1500 x 600


60 x 24


1800 x 600


72 x 24



For other modifications please don't hesitate to ask




Additions and optional extras

Options available at additional cost include:

  Compression fittings (instead of threaded bosses per 4) 19.50
  Shower take-off 19.50
  Additional Tappings (pairs) 18.00
  Secondary return 12.00
  Immersion Heater (Incalloy) 3kW alloy coated (corrosion resistant) 36.00
  Drain (threaded boss) 9.50

Ball valve and overflow fittings (combination models - supplied loose - not installed)


  Additional immersion boss (already supplied with one) 18.00
  Gravity boiler coil with 28mm connections (Large bore for AGA, wood burner etc) Please see this section 95.00

(Please add to stated price)

Positioning tappings to your specification does not normally attract a supplementary charge





The following represents the full range of cylinders available with 'gravity' heat exchangers. As mentioned, please check with your hardware manufacturer for the recommended minimum size of cylinder for your installation. These may be suitable for systems where the heat source has a low output.

900 x 300 55 36 x 12 POA
1050 x 300 65 42 x 12 POA
1200 x 300 75 48 x 12 POA
1500 x 300 96 60 x 12 POA
1800 x 300 114 72 x 12 POA
900 x 350 74 36 x 14 POA
1050 x 350 90 42 x 14 POA
1200 x 350 103 48 x 14 POA
900 x 375 87 36 x 15 POA
1050 x 375 103 42 x 15 POA
1200 x 375 118 48 x 15 POA
750 x 400 80 30 x 16 POA
825 x 400 89 33 x 16 POA
900 x 400 96 36 x 16 POA
1050 x 400 114 42 x 16 POA
675 x 450 86 26 x 18 POA
750 x 450 95 30 x 18 POA
825 x 450 109 33 x 18 POA
900 x 450 117 36 x 18 POA




Hot water cylinders for AGA, Rayburn and Wood Burning stoves

All cylinders are compliant with Part L Building Regulations.



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