The CSI Primary band A Condensing Boiler provides low cost heating solutions for comfortable living with exact operating settings for efficient control.

At 90.2% efficient, it will give savings of over 30% on fuel bills against an old cast iron boiler

  • Fully Modulating Burner and Fan
  • Built-in Automatic Bypass
  • Built-in Condensate Trap and Flexible Condensate Pipe
  • Fan Overrun to Clear the Combustion Chamber Quicker
  • Frost Protection
  • Extended Anti Cycling Device Allowing the Boiler to Still Fire if the Return Temperature Drops Significantly
  • Easy to Access All Major Components from the Front + Controls Under Lift-up Flap
  • Colour Coded, Compact and Standardised Valves that Sit Close to the Wall
  • Integrated Isolation Valves rather than Tails
  • Comes Pre-wired
  • Rear Piping / Stand Off Bracket Available
  • Fully Insulated Casing Ensures Minimal Noise
  • Straightforward Commissioning Process
  • Flue Gas Analysis Points on Flue

The CSI PRIMARY is the perfect high efficiency solution for homes with a traditional open-vented system providing heating only, or heating and hot water with an indirect cylinder. Suitable for new installations, it is also ideal replacements for old cast iron boilers and with certified efficiencies of 90.2%, deliver fuel savings of up to 30%, which means lower gas bills. That’s why they’re recommended by the Energy Saving Trust.

In fact boilers in the CSI range are more efficient than many other gas boilers on the market.

The CSI PRIMARY is designed to extract more heat from a smaller quantity of fuel by using a patented secondary aluminium heat exchanger which captures and uses latent heat from the flue gasses.

The CSI PRIMARY provides an extremely cost-effective high efficiency solution for traditional open vent systems. It can be used in for heating only, or to also provide indirect heating for a cylinder. Compared to an old cast iron boiler, your customers could enjoy savings of up to 30% on their heating bills. CSI boilers are backed up by a three-year parts and labour guarantee with the option to extend up to a total of five years for complete peace of mind.

CSI PRIMARY – modulating CH output from 13.0 – 24.8kW

CSI Primary AAA Boiler

Flue Options

CS80 Inside View

The CSI Primary band A Condensing Boiler requires a standard 1 metre horizontal flue kit, or a vertical flue accessory kit which can be extended to 2.5 metres horizontal or 3.5 metres vertical.

The flue arrangements specified should fit most requirements, however, alternative systems (twin or 125mm) are available for longer flue distance.

See installation manual for all flue options.

CS80 Inside View
PartDescriptionBarcodeRavenheat Part No.
1Vertical flue terminal kit50600221419950019TER1102010
290o boiler bend5060022141209CSIFB
3Straight flue header50600221411865094110B
41000mm flue extension5060022141339PRFE
5External flue collarSupplied with no 6SS
6Horizontal flue kit50600221412305780FKB
745o in line bend5060022141247PR45FBI
890o in line bend5060022141063PR90FBI
9Vertical lead flashing50600221410630019TEG06005
10Plume kit50600221411421019TER1101/0
Flue Diagram

Easily Installed Neat Connections

Neat Connections

Quality Assurance

Ravenheat not only operate a quality ISO9002 system. Indeed we hold the highest accolade in design manufacturing excellence, being one of the new manufacturers to hold ISO9001:2001 system for quality of design, something very few boiler manufacturers have achieved.

This quality system ensures you, the customer, of Ravenheat’s commitment to excellence right across the product range.

*Image for demonstration purposes only.

Boiler Specification

ModelCSI Primary AAA
Input Max-Min NettBtu/h
84.500 - 44.500
24.8 - 13.0
Domestic Hot Water
Output Max-Min AdjustableBtu/h
87.200 - 45.700
25.6 - 13.4
Max/Min Net Efficiency103.1 / 96.8%
Maximum Central Heating TemperatureoC80o
Flow & Return Coppermm22
Gas Connectionmm15
Condensing Pipe ¾ Push Fit Overflow Pipe
Flue Sizemm100
Electrical Mains Supply230v 50Hz Fused 3amp
Nat Gas Band A


Boiler must be correctly installed. Boiler must be commissioned by a Gas Safe Registered Engineer. Boiler must be registered with Ravenheat upon purchase (so 3 year warranty can be activated, Band A models only). Boiler must be correctly maintained and serviced by a qualified, competent person. For any other information please refer to the user guide and installation instructions. For more information on warranties please view our Warranty Terms & Conditions.

Boiler Dimensions

Technical After-Sales Service

Ravenheat has a technical helpline at its central headquarters in Leeds. Service engineers and their customers have the satisfaction of knowing they will receive advice, and the knowledge that one of Ravenheat’s own technicians is on hand should an on-site visit be required.

Ravenheat only use their own highly qualified technicians thereby ensuring the highest quality and most reliable customer care.