Navien NCB300 Combi Gas Boilers
Compact Power and Proven Reliability
Engineered for reliability and efficiency, the NCB300 delivers exceptional hot water performance in a compact, durable design. With its space-saving build and premium quality, it offers outstanding value — high-end performance at an entry-level price.
- Gas
- Combi
The Navien NCB300 combines efficiency, reliability, and smart technology in a compact design. With extended venting up to 8 metres and compatibility with LPG and natural gas (conversion kit included), it offers flexible installation for a variety of homes.
Enjoy A+ energy efficiency for ultra-low running costs, plus smartphone control, weather forecasting, and geofencing for effortless comfort and convenience. Built with stainless steel heat exchangers and hydrogen-ready (20% blend) technology, it’s engineered for long-term durability and future sustainability — all backed by a 5-year parts and labour warranty for total peace of mind.
The Navien NCB300 Series delivers outstanding efficiency, compact design, and reliable performance across four models — 28kW, 30kW, 37kW, and 41kW. Each model is engineered to meet different home heating and hot water demands, offering flexible installation options and long-lasting durability. Whether you need consistent hot water for one shower or a system that supports multiple outlets, there’s an NCB300 to suit your property perfectly.
| Model | NCB300-28K | NCB300-30K | NCB300-37K | NCB300-41K |
|---|---|---|---|---|
| Shower Rating | 1 shower | 1 shower + 1 tap | 2 showers | 2 showers + 1 tap |
| Heat Input Range (kW) | 24.7 / 4.3 | 24.7 / 4.3 | 26.8 / 4.6 | 26.8 / 4.6 |
| Modulation Ratio (CH) | 6:1 | 6:1 | 6:1 | 6:1 |
| CH Output Range @ 80/60°C (kW) | 24.0 / 4.2 | 24.0 / 4.2 | 26.0 / 4.5 | 26.0 / 4.5 |
| DHW Heat Input Range (kW) | 28.0 / 4.3 | 30.0 / 4.3 | 37.0 / 4.6 | 41.0 / 4.6 |
| DHW Output Range (kW) | 28.0 / 4.3 | 30.0 / 4.3 | 37.0 / 4.6 | 41.0 / 4.6 |
| DHW Flow Rate @ 25°C Rise | 16.0 l/min | 17.2 l/min | 21.3 l/min | 23.6 l/min |
| DHW Flow Rate @ 35°C Rise | 11.5 l/min | 12.3 l/min | 15.2 l/min | 16.8 l/min |
| DHW Flow Rate @ 45°C Rise (Kitchen) | 9.0 l/min | 9.6 l/min | 11.8 l/min | 13.1 l/min |
| TDR (Total Modulation Ratio) | 7:1 | 7:1 | 8:1 | 9:1 |
| Flue System | Coaxial Ø60/100mm | Coaxial Ø60/100mm | Coaxial Ø60/100mm | Coaxial Ø60/100mm |
| Max. Horizontal Flue Length | 8m | 8m | 8m | 8m |
| Max. Vertical Flue Length | 8m | 8m | 8m | 8m |
| Lift Weight | 29kg | 29kg | 33kg | 33kg |
| Dimensions (W x D x H) | 395 × 285 × 680mm | 395 × 285 × 680mm | 395 × 285 × 680mm | 395 × 285 × 680mm |
| ErP Efficiency Rating | A (93%) | A (93%) | A (93%) | A (93%) |
| ErP Efficiency with Smart Plus (x3) | A+ (98%) | A+ (98%) | A+ (98%) | A+ (98%) |
| NOx Classification | Class 6 | Class 6 | Class 6 | Class 6 |
All NCB300 models feature stainless steel heat exchangers, hydrogen-ready (20% blend) technology, and a 5-year parts and labour warranty — ensuring long-term reliability, lower emissions, and future-ready efficiency.
Compact, high-performance design – perfect for smaller homes and apartments.
ErP A+ rated efficiency – ultra-low running costs and reduced emissions.
Smart control ready – remote operation, geofencing, and weather forecasting.
Hydrogen-ready (20% blend) – futureproof for cleaner energy.
Stainless steel heat exchangers – durable and highly efficient.
5-year parts & labour warranty – reliable performance you can trust.
What’s Included with The Boiler Team Installation?
- Installed by a local Gas Safe engineer
- Old boiler & tanks removed (if applicable)
- All waste cleared, including the old boiler
- Flue installation for optimal performance
- Magnetic filter to protect your system
- System cleanse + protective treatments included
- Pipework upgrades were required
- Premium copper & fittings supplied
- Electrical setup, including wireless thermostat (if applicable)
- Delivery & setup arranged for you
- Warranty registration & certification handled
- Manufacturer parts & labour warranty included
- 10-Year workmanship guarantee from The Boiler Team
Frequently Asked Questions About Navien Boilers
Find clear, expert answers about Navien gas combi boilers — discover their features, efficiency benefits, and how to choose the best gas boiler for your home.
The Navien NCB300 is a high-efficiency gas condensing combi boiler designed to provide powerful heating and instant hot water from a single compact unit. It’s ideal for modern homes, apartments, and small to medium-sized properties looking for energy-efficient comfort and reliable performance.
The Navien NCB300 runs on natural gas as standard, offering clean, efficient, and affordable home heating. It’s also compatible with LPG using the included conversion kit, giving flexibility for properties not connected to the gas mains..
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The NCB300 range includes four output options — 28kW, 30kW, 37kW, and 41kW — allowing you to match your home’s heating and hot water demand perfectly. From single-bathroom flats to busy family homes, there’s a model to suit your lifestyle.
Depending on the model, the NCB300 delivers up to 23.6 litres per minute of domestic hot water — enough to run two showers and a tap simultaneously. It ensures a steady, comfortable flow even during high-demand periods.
Yes! The NCB300 works seamlessly with Navien Smart Control via smartphone or tablet. You can adjust heating and hot water settings remotely, and enjoy geofencing and weather forecasting features for maximum efficiency.
Yes — the Navien NCB300 is hydrogen-ready up to 20% blend, meaning it’s prepared for the UK’s transition to cleaner, more sustainable gas fuels in the future.
The NCB300 operates quietly, thanks to its advanced stainless steel heat exchangers and smooth modulating system. It’s an excellent choice for kitchens, cupboards, or open-plan living spaces where low noise levels matter
Every Navien NCB300 gas combi boiler comes with a 5-year parts and labour warranty, offering long-term peace of mind and protection backed by Navien’s trusted engineering.
Because it offers premium performance, energy efficiency, and smart-ready technology in a compact, affordable design. With A-rated efficiency, hydrogen-readiness, and Navien’s proven reliability, it’s one of the best-value gas combi boilers available today.
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