Navien LCB700 Blue Flame Combi – Internal Model
The Navien LCB700 Blue Flame Combi sets a new standard for high-efficiency oil boilers, becoming the first in the UK to achieve an A+ energy rating. Designed with cutting-edge blue flame technology and advanced smart controls, it delivers exceptional performance, lower running costs, and eco-friendly heating for modern homes.
Engineered for simplicity and reliability, the LCB700 features easy installation options, including a combined PRV/condensate drain and flexible pipework design. The result? A powerful, compact oil boiler that combines innovation, convenience, and long-term efficiency — a true game-changer in home heating.
- Oil
- Combi
Choose the Navien LCB700 Blue Flame Combi for an oil boiler that’s built for the future. HVO compatible and equipped with advanced Blue Flame technology, it delivers superior efficiency, ultra-low NOx emissions, and A+ energy performance for cleaner, more sustainable heating.
Designed with both homeowners and installers in mind, the LCB700 features a lightweight, compact design for easy installation and flexible flue venting up to 21m. Its stainless steel heat exchangers ensure long-term durability, while the intuitive text-driven display and Smart Plus control pack provide intelligent management of up to three heating zones.
With a 10-year parts and labour warranty, class-leading energy efficiency, and a modern, clean look, the LCB700 offers unbeatable reliability, comfort, and value — the perfect choice for efficient, future-proof oil heating.
The Navien LCB700 Blue Flame Combi range combines A-rated efficiency, ultra-low NOx emissions, and HVO-ready Blue Flame technology for cleaner, more sustainable heating. With Smart Plus controls, flexible flue options up to 21m, and a compact, installer-friendly design, it’s one of the most efficient oil combi boilers available for UK homes.
Navien LCB700 Blue Flame Combi – Technical Data
| Specification | 21kW Models (RS / LS / LC / RSX / LSX / LCX) | 28kW Models (RS / LS / LC / RSX / LSX / LCX) | 36kW Models (RS / LS / LC / RSX / LSX / LCX) |
|---|---|---|---|
| Central Heating Output (80/60°C) | 16–21kW | 21–28kW | 29–36kW |
| Central Heating Output (50/30°C) | 23.0kW | 30.3kW | 39.0kW |
| Domestic Hot Water (DHW) Flow Rate | 14 L/min | 18 L/min | 20 L/min |
| DHW Temperature Range | 30–60°C (default 50°C) | 30–60°C (default 50°C) | 30–60°C (default 50°C) |
| Hot Water Temp Rise (90L draw) | 40°C | 40°C | 40°C |
| Flue Type | Coaxial plastic Ø60/100mm | Coaxial plastic Ø60/100mm | Coaxial plastic Ø60/100mm |
| Max Flue Length (Horizontal) | 20m | 20m | 20m |
| Max Flue Length (Vertical) | 21m | 21m | 21m |
| Dimensions (W × D × H) | 600 × 600 × 860mm | 600 × 600 × 860mm | 650 × 673 × 900mm |
| Weight | 91kg | 91kg | 98kg |
| ErP Efficiency | A (93%) | A (93%) | A (93%) |
| ErP Efficiency with Smart Plus Controls | A+ (98%) | A+ (98%) | A+ (98%) |
| NOx Emissions (mg/kWh) | 57.2 | 57.2 | 63.2 |
| EN Regulation Compliance | EN13203-1 | EN13203-1 | EN13203-1 |
A+ Rated Efficiency – The UK’s first Blue Flame oil combi boiler with top-tier energy performance.
HVO Compatible – Ready for renewable heating fuels for a sustainable future.
Ultra-Low NOx Emissions – Cleaner, greener combustion with Blue Flame technology.
Smart Plus Ready – Upgrade to A+ (98%) efficiency with intelligent control options.
Compact & Lightweight – Easy to install with flexible 21m flueing options.
Durable Stainless Steel Heat Exchangers – Built for long-term reliability.
10-Year Warranty – Peace of mind backed by Navien engineering excellence.
What’s Included with The Boiler Team Installation?
Installed by a local Oftec engineer
Oil Filters / Fire Valve Upgrade Pack Included
Old boiler & tanks removed (if applicable)
All waste cleared, including old boiler
Flue installation for optimal performance
Magnetic filter to protect your system
System cleanse + protective treatments included
Pipework upgrades where 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 Oil combi boilers — discover their features, efficiency benefits, and how to choose the best gas boiler for your home.
The Navien LCB700 Blue Flame Combi is a high-efficiency oil boiler designed for modern homes that need reliable heating and instant hot water. It’s the first A+ rated Blue Flame oil boiler in the UK, offering exceptional efficiency, ultra-low emissions, and compatibility with smart controls.
The LCB700 runs on kerosene oil as standard but is also HVO compatible, allowing homeowners to switch to a renewable, low-carbon fuel without changing the boiler — making it a future-proof heating solution.
Blue Flame technology ensures a cleaner, more efficient burn compared to traditional yellow flame oil boilers. This results in ultra-low NOx emissions, improved performance, and reduced fuel consumption — helping the environment and your wallet.
The LCB700 achieves ErP A-rated efficiency (93%) and can reach A+ (98%) when combined with the Navien Smart Plus control pack, offering outstanding energy savings and lower running costs.
Yes — the LCB700 is designed with installers in mind. Its lightweight build, compact design, and flexible flueing options up to 21m make installation quick and straightforward, even in tight spa
Absolutely. The LCB700 Combi models are ideal for small to medium-sized properties, offering instant hot water and powerful heating without the need for a separate hot water cylinder.
The LCB700 is built to last, featuring stainless steel heat exchangers that provide superior corrosion resistance and long-term efficiency, ensuring years of reliable performance.
Every Navien LCB700 Blue Flame Combi comes with a 10-year parts and labour warranty, giving homeowners complete peace of mind and long-term protection.
Because it combines premium efficiency, smart-ready technology, HVO compatibility, and clean, low-emission heating in a sleek, installer-friendly design. It’s the next generation of oil combi boilers — efficient, sustainable, and built to perform.
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