Navien NCB300 28kW Gas Combi Boiler – Stainless Steel Heat Exchanger | ErP A/A+ | LPG Conversion Kit Included
This compact 28kw gas combination boiler features a stainless steel heat exchanger, 26kW central heating output, 37 kw domestic hot water peak. As standard, the boiler has an ErP a efficiency of 93%, increasing to an erp a+ efficiency of 98% when using the optional Navien smart plus controls. This results in a 7:1 modulation ratio. An LPG conversion kit is provided as part of this package. The flue can extend up to 8m. The Navien NCB300 is hydrogend blend ready to 20%. It is rated ipx4. The emissions class of this product is NOx class 6. Dimensions are 680 x 395 x 285 mm. Its net weight is 29 kg and has a lifting weight of 30 kg. There is a 5 year parts and labour warranty offered with this product (subject to terms and conditions - registration at time of installation required).
The Navien NCB300 offers the stainless steel heat exchanger found in Navien’s premium models in a compact 28kw body. This stainless steel heat exchanger will provide better resistance against corrosion caused by condensation compared to some aluminium alternative products and maintain its efficiency and reliability through the lifetime of the product, independent of inhibitor treatment.
The 7:1 modulation ratio allows the burner to reduce power output to approximately 4 kw at minimum. This means that the boiler will modulate to match the load requirement instead of turning completely on/off at low loads. This is especially beneficial during the transitional seasons and when used with radiator sizes designed for lower temperature flows. The 37 kw DHW output provides support for single shower/basin operation (11.5 l/min @ 35 °c rise), or simultaneous use of multiple appliances (16.0 l/min @ 25 °c rise). Although the boiler itself achieves an erp a efficiency of 93%, addition of the optional Navien smart plus controls increase the efficiency to an ErP a+ efficiency of 98%.
An LPG conversion kit is provided in the packaging allowing customers who do not have access to mains gas to convert their appliance for off grid applications. The maximum flue length available is 8 m (horizontal or vertical, 60 /100 coaxial) providing Installers with greater freedom to locate the appliance further from external wall surfaces. The Navien NCB300 is also capable of operating with blends of Hydrogen up to 20 % without requiring any additional modifications. All installations should be completed by a gas safe registered installer.
Must be installed by a Gas Safe registered engineer.
Key Features & Benefits
Stainless Steel Heat Exchanger - Resists condensate corrosion more effectively than aluminium alternatives - key long-term reliability advantage without sole dependence on inhibitor condition.
ErP A (93%) as Standard - ErP A+ (98%) with Smart Plus Controls - Lowest running costs achievable from this boiler require the addition of Navien Smart Plus controls.
7:1 Modulation Ratio - Burner turns down to approximately 4kW minimum. Reduces wear, improves seasonal efficiency and maintains stable room temperatures without overshoot.
37kW DHW Output - 11.5 L/min at 35°C rise or 16.0 L/min at 25°C rise. Single shower and basin simultaneous draw for small to medium homes.
LPG Conversion Kit Included - No separate sourcing required for off-grid installations.
8m Maximum Flue Length - Horizontal or vertical. Extends installation options beyond short-flue competitors at this price point.
Hydrogen Blend Ready to 20% - Compatible with UK government's current hydrogen-to-grid blend target without modification.
Navien Smart Plus Compatible - Smartphone control, geofencing and weather compensation. Required for A+ ErP rating.
IPX4 Water Resistance - Suitable for garages, outbuildings and splash-exposed locations.
NOx Class 6 - Lowest NOx classification under EN 15502.
5-Year Parts & Labour Warranty - Register at installation. T&Cs apply - check Navien's current requirements at point of installation.
Ideal For
Small to medium homes with one bathroom and shower
Tight installation spaces where cabinet dimensions and lift weight matter
Off-grid and rural LPG properties - conversion kit in the box
Installers needing extended flue flexibility
Properties preparing for hydrogen-blended gas supply
Smart home users wanting Navien Smart Plus integration
Compact, super efficient & ready to take on hydrogen too - stainless steel heat exchanger, an A+ rating and LPG conversion kit comes with the Navien NCB300 28kW, which just so happens to be in stock and ready to go. We've also got the larger output models in the Navien NCB range if you need a bigger one for a bigger home. One more thing - this needs to be installed by a Gas Safe engineer, not just anyone.
Specification
Navien NCB300 Combi Gas Boiler - 28kW Specification
Brand
Navien
Model
NCB300 28kW
Boiler Type
Gas combination boiler (condensing)
CH Output
26 kW (88,715 BTU)
DHW Max Output
37 kW
DHW Flow Rate (35°C rise)
11.5 L/min
DHW Flow Rate (25°C rise)
16.0 L/min
Modulation Ratio
7:1
ErP Heating Efficiency
A – 93% (standard)
ErP with Smart Plus Controls
A+ – 98%
Heat Exchanger
Stainless steel
Fuel Type
Natural gas / LPG (LPG conversion kit included)
NOx Class
6
Hydrogen Ready
Yes – 20% blend
Flue Size
60/100 coaxial
Max Flue Length
8m horizontal or vertical
IP Rating
IPX4
Dimensions (H × W × D)
680 × 395 × 285mm
Weight
33kg (lift weight 29kg)
Shower Capability
1 shower
Warranty
5 years parts and labour (T&Cs apply – register at installation)
Features
Navien NCB300 Combi Gas Boiler - 28kW Features
Stainless Steel Heat Exchanger - Resists condensate corrosion more effectively than aluminium alternatives - key long-term reliability advantage without sole dependence on inhibitor condition.
ErP A (93%) as Standard - ErP A+ (98%) with Smart Plus Controls - Lowest running costs achievable from this boiler require the addition of Navien Smart Plus controls.
7:1 Modulation Ratio - Burner turns down to approximately 4kW minimum. Reduces wear, improves seasonal efficiency and maintains stable room temperatures without overshoot.
37kW DHW Output - 11.5 L/min at 35°C rise or 16.0 L/min at 25°C rise. Single shower and basin simultaneous draw for small to medium homes.
LPG Conversion Kit Included - No separate sourcing required for off-grid installations.
8m Maximum Flue Length - Horizontal or vertical. Extends installation options beyond short-flue competitors at this price point.
Hydrogen Blend Ready to 20% - Compatible with UK government's current hydrogen-to-grid blend target without modification.
Navien Smart Plus Compatible - Smartphone control, geofencing and weather compensation. Required for A+ ErP rating.
IPX4 Water Resistance - Suitable for garages, outbuildings and splash-exposed locations.
NOx Class 6 - Lowest NOx classification under EN 15502.
