Navien NCB-240 Boiler Instruction Manual
Navien NCB-240 Boiler
Navien NCB-240 Boiler
Navien NCB-240 Boiler
Navien NCB-240 Boiler Instructions
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Navien NCB-240 Boiler Specifications
| Feature | Specification (NCB-240) |
|---|---|
| Model Number | NCB-240 |
| Space Heating Input (Min/Max) | 18 / 120 MBH |
| Space Heating Capacity | 109 MBH |
| Net AHRI Rating Water | 95 MBH |
| AFUE | 93.3% |
| DHW Input Ratings (Min/Max) | 18,000 / 199,900 BTU/H |
| DHW Water Pressure | 15-150 psi |
| DHW Minimum Flow Rate | 0.5 GPM (1.9 L/m) |
| DHW Flow Rate @ 77°F (43°C) Temp. Rise | 4.5 GPM |
| DHW Supply Connection Size | 3/4 in NPT |
| Cold Water Input Connection Size | 3/4 in NPT |
| Dimensions (W x H x D) | 17 in x 28 in x 12 in |
| Weight | 84 lbs (38 kg) |
| Installation Type | Indoor Wall-Hung |
| Venting Type | Forced Draft Direct Vent |
| Ignition | Electronic Ignition |
| Natural Gas Supply Pressure (from source) | 3.5 in-10.5 in WC |
| Propane Gas Supply Pressure (from source) | 8.0 in-13.5 in WC |
| Natural Gas Manifold Pressure (Min/Max) | -0.06 in WC / -1.2 in WC |
| Propane Gas Manifold Pressure (Min/Max) | -0.03 in WC / -0.98 in WC |
| Gas Connection Size | 3/4 in NPT |
| Power Supply | 120V AC, 60Hz |
| Maximum Power Consumption | 200W (max 2A) |
| Casing Materials | Cold-rolled carbon steel |
| Heat Exchanger Materials (Primary, Secondary, DHW) | Stainless Steel |
| Exhaust/Intake Venting Materials | 2 in or 3 in PVC, CPVC, Polypropylene, Special Gas Vent Type BH (Class III, A/B/C) |
| Vent Clearances | 0 in to combustibles |
| Safety Devices | Flame Rod, APS, Gas Valve Operation Detector, Ignition Operation Detector, Water Temperature High Limit Switch, Exhaust Temperature High Limit Sensor |
| Maximum Altitude (Natural Gas) | 10,100 ft (3,078 m) |
| Maximum Altitude (Propane Gas) | 4,500 ft (1,370 m) |
| DHW Temperature Setting Range | 86-140°F |
| Space Heating Supply Temperature Range (Default) | 86-140°F |
| Space Heating Return Temperature Range (Default) | 86-140°F |
Navien NCB-240 Boiler Details
The Navien NCB-240 combi-boiler is engineered with several advanced safety and operational features to ensure reliable performance. It boasts automatic restart capabilities after a power interruption, eliminating the need for manual resets. Integrated freeze protection activates a heating cycle if internal temperatures drop too low, safeguarding internal components. For electrical safety, a short-circuit protection system uses internal glass fuses to cut off the gas supply immediately. Furthermore, lightning protection is provided through both internal and external grounding mechanisms.
Maintaining a healthy environment, the boiler incorporates robust carbon monoxide protection, continuously monitoring the air-to-gas ratio and combustion rate for safety. An auto fan detection system oversees fan rotation, ensuring proper operation, with any fan failure resulting in an automatic shutdown of the boiler. To prevent damage from excessive temperatures, a boiling prevention mechanism automatically ceases boiler operation if overheating occurs. These proactive measures contribute to the unit's overall safety and longevity.
The user-friendly front panel serves as the central hub for adjusting temperatures, viewing operational status, and checking error codes. It features various icons for critical information like outdoor reset, combustion activity, anti-freeze mode, and DHW operation. Internally, a factory-installed, pressure-sensing low water cut-off (LWCO) device ensures the system maintains adequate water levels, automatically replenishing if needed. If replenishment isn't completed, an E351 error code prompts a manual reset, highlighting the system’s intelligent water management.
For domestic hot water (DHW) supply, the NCB-240 operates on demand, initiating hot water production when a flow of at least 0.5 GPM is detected. This method is highly efficient, prioritizing DHW needs over space heating when demand arises. Its primary, secondary, and DHW heat exchangers are all constructed from durable stainless steel, optimizing heat transfer in a compact design. A built-in flow restrictor at the cold water inlet adapter manages water flow, available in color-coded variations, with the orange restrictor allowing 5.6 GPM for the NCB-240 model.
Proper installation is crucial, especially regarding condensate management. The boiler produces acidic condensate (pH 3-5) that requires appropriate disposal via a drain, laundry tub, or neutralizer. For high-altitude installations, the unit features an automatic derating function. An optional NaviLink Wi-Fi Control accessory elevates user convenience, allowing remote adjustment of water temperatures, access to usage data, and reception of diagnostic notifications directly through a smartphone or tablet app, compatible with both single and cascade systems.
Frequently Asked Questions (FAQs)
Can't find the answer you need? Here are some frequently asked questions about the Navien NCB-240 Boiler, and we answer them below.
