A combi (or combination boiler) is a compact and highly efficient unit giving all the heating and hot water you need, with significant savings on running and installation costs.

Unlike a conventional heating and hot water system, a combi boiler system does not store domestic hot water. It heats water directly from the cold mains - as you use it. There's no hot water cylinder, no tank in the loft (and so less risk of freezing and flooding), and none of the connecting pipework. So you not only save space, but also reduce hot water costs - which can account for up to 60% of a typical domestic fuel bill.

A combi also supplies hot water at mains pressure, giving you exhilarating power showering without the need for a pump. And as, on average, a shower uses considerably less water than a typical bath, the savings on hot water costs and water consumption can be significant.

A condensing boiler is more efficient due to its ability to extract more heat from the flue gases normally lost to the environment through the flue system.

All the Greenstar CDi models use the same Aluminium-Silicon heat cell with an extra large surface area.

As the flue gases pass through the heat exchanger this extra surface area cools the flue gases to around 55°C whereupon the latent heat within, which would normally be lost to the atmosphere, is instead released and applied to the system.

It is this ability to extract as much heat as possible from the gas it burns that gives the Greenstar CDi series an exceptionally high level of operating efficiency.

This higher efficiency is recognised within section L of the Building Regulations, subsequently achieving a higher SAP or NHER rating.

Key features of the Greenstar CDi condensing boilers include the separate plate domestic hot water heat exchanger, which is guaranteed for 5 years.*

This, combined with the 'keep hot' facility, ensures that hot water is delivered instantly to the tap.

*Subject to conditions

The Greenstar CDi series
Hot water mode

Whenever a hot water tap is turned on the incoming mains water will activate a flow turbine which, via the electronic control system, ignites the pre-mix burner. Boiler output is automatically boosted to maximum to heat the incoming cold water as it passes through the heat exchanger. Electronic controls modulate the boiler output downwards to ensure the hot water temperature remains between 40 and 60ºC (as set by the consumer).

Keep hot facility

All the Greenstar CDi combi models have an in-built keep hot facility which will keep the primary water within the heat cell hot. This will ensure that hot water is delivered instantly to the opened outlet.

Eco mode

With the Eco mode button activated the keep hot facility is de-energised and the hot water will be heated from cold. A slight delay should be expected before the hot water is at full temperature when in the Eco mode.

Central heating mode

On a Central Heating demand, the boiler will initially fire at minimum output before modulating upwards to meet the actual system requirement. Electronics within the boiler continually monitor the heating flow temperature increasing or decreasing output on demand. An anti-cycling device makes the Greenstar CDi range particularly suitable for use on systems with TRV's (Thermostatic Radiator Valves).

The Worcester Greenstar CDi condensing boiler range offers models in 27, 30, 37 and 42kW models. This broad range of outputs and increased flow rates is available in both natural gas and LPG appliances.

Fully condensing in both CH and DHW modes - up to an extra 10% saving on fuel bills
Modulating circulating pump - energy saving and system tolerant
27kW, 30kW, 37kW and 42kW DHW outputs - boiler for all property types
Compact dimensions - siting flexibility
WB5 series heatcell - robust cast aluminium/silicon construction
Heatronic III control system - sophisticated boiler management
Compact hydraulic - efficient and reliable
Wall mounting frame with pipes behind - no exposed pipework
Low NOx and CO2 emissions - environmentally friendly
Keep hot facility - instantly available hot water
DHW and CH temperature control - consumer comfort flexibility
Central heating boost function - rapid heat up function 

DELIVERY IS NORMALLY 3/4 WORKING  DAYS.

Please note prices in drop down below exclude VAT.