The Navien NCB300-28K is a wall-hung, room-sealed gas condensing combi boiler rated at 28kW, supplied here complete with the Navien 1000mm Standard Horizontal Flue Kit (GXXX002208) and an Adey MagnaClean Micro 1 Filter (FL1-03-07129). Navien's entry-level combi model shares its core componentry with the larger NCB300/500/700 range, including dual stainless steel heat exchangers for long-term durability and a 6:1 turndown ratio for smooth modulation. The bundled Adey filter protects the boiler's heat exchangers from circulating magnetite and debris from day one, supporting the boiler's 5-year parts and labour warranty.
11.5 l/min
DHW Flow (ΔT35°C)
5 yrs
Parts & Labour Warranty
Gas Safe Registration Required
Installation, commissioning and servicing of this boiler must be carried out by a Gas Safe registered engineer. The horizontal flue must be positioned in accordance with the clearances set out in the manufacturer's installation and operation manual, and a Benchmark commissioning checklist must be completed and left with the end user.
Bundle Contents & LPG Conversion
This listing supplies three separate boxed items designed to be installed together: the NCB300-28K boiler (PNCB3000028L001), the 1000mm Standard Horizontal Flue Kit (GXXX002208), and the Adey MagnaClean Micro 1 Filter (FL1-03-07129, 22mm compression). The boiler is shipped ready to fire on natural gas; an LPG conversion kit is included in the boiler packaging for field conversion by a suitably qualified Gas Safe engineer, but is not fitted as standard.
Why This Bundle
Dual Stainless Steel Heat Exchangers
The primary and secondary heat exchangers are both stainless steel rather than aluminium, giving strong resistance to corrosion from acidic condensate and supporting long-term reliability over the boiler's working life.
6:1 Turndown Ratio
A wide 6:1 modulation range lets the burner idle down to a low minimum output on milder days, avoiding the short-cycling that wastes gas and wears components faster on boilers with a narrower turndown.
Hydrogen-Ready (20% Blend)
The NCB300 is tested and approved for use with up to a 20% hydrogen blend in the gas supply, helping future-proof the installation against the anticipated transition of the UK gas network.
ErP A+ with Smart Plus
Paired with a Navien Smart Plus wireless thermostat, the system efficiency rating rises from ErP A (93%) to ErP A+ (98%), thanks to weather forecasting and location-based heating adjustments.
Adey Micro 1 Filter Included
The bundled Adey MagnaClean Micro 1 is a compact 22mm in-line magnetic filter with 360° rotational valves for flexible installation, and full vent, drain and flush capability for straightforward servicing.
Compact, Lightweight Design
At 395 x 285 x 680mm and 29kg lift weight, the NCB300 is built for easy cupboard-fit installation in smaller properties, without sacrificing DHW performance.
Technical Specification
| General |
| Boiler article number |
PNCB3000028L001 (NCB300-28K) |
| Flue kit article number |
GXXX002208 (1000mm Standard Horizontal Flue Kit, 60/100mm) |
| Filter article number |
FL1-03-07129 (Adey MagnaClean Micro 1, 22mm) |
| Boiler type |
Wall-hung, room-sealed, fan-assisted condensing combi (B23-C13-C33-C53-C83) |
| Fuel type |
Natural gas (LPG conversion kit included, field conversion required) |
| Dimensions (W x D x H) |
395 x 285 x 680 mm |
| Guarantee |
5 years parts and labour |
| Heating Performance |
| Heat input range |
4.3 – 24.7 kW |
| Heat output range (80/60°C) |
4.2 – 24.0 kW |
| Modulation (max/min) |
6:1 |
| Domestic Hot Water |
| DHW heat input / output range |
4.3 – 28.0 kW |
| DHW flow rate (ΔT = 25°C) |
16.0 l/min |
| DHW flow rate (ΔT = 35°C) |
11.5 l/min |
| DHW flow rate, kitchen tap (ΔT = 45°C) |
9.0 l/min |
| DHW turndown ratio |
7:1 |
| Performance & Emissions |
| ErP efficiency |
A (93%) — A+ (98%) with Smart Plus control |
| NOx classification |
Class 6 |
| IP rating |
IPX4 |
| Sound level |
52 dBA |
| Lift weight |
29 kg |
| Flue |
| Flue diameter |
Coaxial 60/100mm |
| Max. horizontal coaxial flue length |
8 m |
| Max. vertical coaxial flue length |
8 m |
| Bundled flue kit length |
1000mm |
Frequently Asked Questions
Does this listing include the boiler, flue, and filter, or do I need to buy them separately?
All three items are included in this single listing: the NCB300-28K boiler (PNCB3000028L001), the GXXX002208 1000mm horizontal flue kit, and the FL1-03-07129 Adey MagnaClean Micro 1 filter.
Can I run this boiler on LPG?
An LPG conversion kit is included in the boiler's packaging as standard, but the boiler ships configured for natural gas. Conversion to LPG must be carried out by a Gas Safe registered engineer holding the appropriate LPG qualification, following the procedure in the service manual.
Why is a magnetic filter included with the boiler?
The Adey MagnaClean Micro 1 protects the boiler's stainless steel heat exchangers from circulating magnetite and debris in the heating system, reducing the risk of blockages and helping protect the manufacturer's warranty.
Is the 1000mm flue kit long enough for my installation?
The bundled kit provides a 1000mm length, suitable for a standard through-wall termination. Runs up to the 8m maximum horizontal length require additional Navien 60/100 extension and bend accessories, sold separately.
What is ErP A+ with Smart Plus, and is it included?
The Smart Plus wireless thermostat and WiFi receiver are sold separately and are not included in this bundle. Pairing one with this boiler raises the system's ErP rating from A (93%) to A+ (98%).
Can I install this boiler myself?
No. UK law requires that all gas boiler installation, commissioning and servicing work is carried out by a Gas Safe registered engineer.
