Navien LCB700 Blue Flame Combi Boiler – External Model
Future-ready Blue Flame performance
The Navien LCB700 Blue Flame Combi Boiler (External Model) sets a new benchmark for oil-fired heating efficiency. As the first A+ rated Blue Flame oil boiler in the UK, it delivers outstanding performance, ultra-low emissions, and cutting-edge smart control compatibility — all designed for modern, energy-conscious homes.
Engineered for easy outdoor installation, the LCB700 features a compact, weatherproof design, flexible pipework options, and a combined PRV/condensate drain for simpler setup and maintenance. With class-leading efficiency and future-ready technology, the LCB700 Blue Flame is the smart choice for homeowners looking for powerful, clean, and reliable heating all year round.
- Oil
- Combi
Choose the Navien LCB700 Blue Flame Combi Boiler for powerful, reliable, and future-ready home heating. Fully HVO compatible and built with advanced Blue Flame technology, it delivers ultra-low NOx emissions, superior efficiency, and class-leading energy savings — making it one of the most eco-friendly oil boilers available today.
Designed with convenience in mind, the LCB700 features a lightweight, compact build for easy installation and flexible flue venting up to 21m, perfect for almost any property layout. Inside, stainless steel heat exchangers ensure long-term performance and durability, while the Smart Plus control pack enables 3-zone heating management and real-time energy monitoring.
With its 10-year parts and labour warranty, clean modern design, and A+ energy efficiency rating, the LCB700 combines innovation, sustainability, and comfort — giving you total peace of mind and lower running costs for years to come.
The Navien LCB700 Blue Flame Combi Boiler delivers high-efficiency oil heating with A+ ErP energy ratings, low NOx emissions, and HVO compatibility for a sustainable future. Its Blue Flame burner technology ensures clean, efficient combustion, while Smart Plus controls help you maximise performance and reduce running costs.
With multiple output options (21kW–36kW), flexible flueing up to 21m, and a compact, installer-friendly design, the LCB700 is perfect for both domestic and commercial oil heating applications.
Navien LCB700 Blue Flame Combi Boiler – Technical Data
| Specification | LCB700 21kW (RS / LS / LC) | LCB700 28kW (RS / LS / LC) | LCB700 36kW (RS / LS / LC) | LCB700 21kW (RSX / LSX / LCX) | LCB700 28kW (RSX / LSX / LCX) | LCB700 36kW (RSX / LSX / LCX) |
|---|---|---|---|---|---|---|
| Heat Output (80/60°C) | 16–21kW | 21–28kW | 29–36kW | 16–21kW | 21–28kW | 29–36kW |
| Heat Output (50/30°C) | 23.0kW | 30.3kW | 39.0kW | 23.0kW | 30.3kW | 39.0kW |
| Max DHW Flow Rate (±15%) | 14 L/min | 18 L/min | 20 L/min | 14 L/min | 18 L/min | 20 L/min |
| DHW Temperature Control Range | 30–60°C (Default 50°C) | 30–60°C (Default 50°C) | 30–60°C (Default 50°C) | 30–60°C (Default 50°C) | 30–60°C (Default 50°C) | 30–60°C (Default 50°C) |
| Max Hot Water Temp Rise (90L draw-off) | 40°C | 40°C | 40°C | 40°C | 40°C | 40°C |
| Flue Size | Coaxial Plastic Ø60/100 | Coaxial Plastic Ø60/100 | Coaxial Plastic Ø60/100 | Coaxial Plastic Ø60/100 | Coaxial Plastic Ø60/100 | Coaxial Plastic Ø60/100 |
| Max Horizontal Flue Length | 20m | 20m | 20m | 20m | 20m | 20m |
| Max Vertical Flue Length | 21m | 21m | 21m | 21m | 21m | 21m |
| Dimensions (HxWxD) | 860 x 600 x 600mm | 860 x 600 x 600mm | 900 x 673 x 650mm | 860 x 600 x 600mm | 860 x 600 x 600mm | 900 x 673 x 650mm |
| Weight | 91kg | 91kg | 98kg | 91kg | 91kg | 98kg |
| ErP Efficiency Rating | A (93%) | A (93%) | A (93%) | A (93%) | A (93%) | A (93%) |
| ErP Efficiency with Smart Plus | A+ (98%) | A+ (98%) | A+ (98%) | A+ (98%) | A+ (98%) | A+ (98%) |
| NOx Emission Rate | 57.2mg/kWh | 57.2mg/kWh | 63.2mg/kWh | 57.2mg/kWh | 62.5mg/kWh | 63.2mg/kWh |
A+ rated efficiency for lower energy bills and reduced emissions
HVO compatible – ready for renewable, sustainable fuel
Ultra-low NOx Blue Flame technology for cleaner combustion
Compact, weatherproof design for easy outdoor installation
Smart Plus control ready – upgrade to 98% efficiency
Durable stainless steel heat exchangers for long-term reliability
10-year parts and labour warranty for total peace of mind
Flexible flueing up to 21m for versatile installation options
High 3-star DHW performance rating for strong hot water output
Future-proof heating solution built for efficiency and sustainability
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 LCB700 is the UK’s first A+ rated Blue Flame oil boiler, offering exceptional efficiency, ultra-low NOx emissions, and Smart Plus control compatibility for intelligent heating management. It’s designed to deliver maximum performance with minimal environmental impact.
Yes! The LCB700 is fully HVO (Hydrotreated Vegetable Oil) compatible, making it a renewable, eco-friendly heating option that reduces carbon emissions and future-proofs your home.
The LCB700 achieves an ErP A rating (93%) as standard, which can be upgraded to an A+ rating (98%) when paired with Navien Smart Plus controls, helping you cut energy bills and boost sustainability.
Yes, the External Model is weatherproof and built for outdoor installation, with a durable, corrosion-resistant casing that protects the boiler in all seasons.
With Blue Flame burner technology and Smart Plus control compatibility, the LCB700 offers industry-leading energy efficiency, ensuring cleaner combustion and lower running costs.
Yes, it’s 3-zone ready with the Smart Plus control pack, allowing you to manage different heating areas independently for greater comfort and control.
The boiler comes with a 10-year parts and labour warranty, giving you long-term peace of mind backed by Navien’s proven reliability and engineering quality.
The LCB700 range includes 21kW, 28kW, and 36kW models, making it suitable for everything from small homes to larger properties with higher heating and hot water demands.
Thanks to its lightweight design, flexible flueing options up to 21m, and combined PRV/condensate drain, the LCB700 is designed for quick installation and straightforward servicing.
Absolutely. The LCB700’s HVO compatibility, Blue Flame technology, and ultra-low NOx emissions make it one of the cleanest and most sustainable oil boilers available in the UK today.
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