Current stock level: In stock as of
Ship out time: Within 1 business day.
Delivery time: 1 to 3 business days to most addresses.
The NCB-240E is the updated and improved combination boiler where technology meets ecology
Heats water only when needed, making it environmentally sound and cost efficient.
It's the ideal solution for people who need both a space heating application and a domestic hot water heater.
Benefits of Hydronic Heating
→ Clean and comfortable: no air movement means low likelihood for creating dust or excessively dry air.
→ Silent: silent heating, with no blowers needed for forced circulation.
→ Comfort: makes people feel warm and comfortable by keeping the floor warm and indoor air fresh.
→ Coverage: radiant heat from the floor to the ceiling.
→ Economical: radiant heat from the floor can send warmth throughout the house even hours after turning off your heater.
High turn down ratio reduces wasted energy and boiler cycling
→ The NCB's sophisticated gas flow control system provides a turn down ratio of 6:1 for heating and 11:1 for DHW. This reduces energy waste and excessive boiler cycling and enhances temperature control for domestic hot water use.
Ultra Condensing Efficiency
→ Navien's condensing technology allows high efficiency heating
→ Significant energy savings over traditional water heaters
Dual Stainless Steel Heat Exchangers
Plus, waterways are all stainless steel. Fittings and components are brass or polypropylene.
→ Longer life expectancy than copper heat exchangers. More resistant to corrosion.
→ Less mineral scaling and deposits
Low NOx Emissions
→ New metal fiber burner delivers a consistent gas/air mixture
→ Less greenhouse gas emissions and acid rain
→ SCAQMD 1146.2 compliant
2" PVC, CPVC, Polypropylene Venting
→ 2" vent allows you to install a flue through an existing vent
→ Schedule 40 2" venting up to 60 feet, but with no elbows
→ 3" vent can be used up to 150' on standard 2" x 3" adapters, but with no elbows
Uses Existing 1/2" Gas Line
→ Dual venturi fan and negative pressure gas valve for better adaptability with low gas pressure
→ Installation in 1/2" gas lines up to 24 feet
Field LP/NG Convertible
→ Allows easy conversion from/to natural gas and liquid propane. Important: Navien water heaters are shipped ready for natural gas. For easy conversion to liquid propane, consult the Gas Conversion Guide.
Low gas pressure operation
→ Navien's innovative negative pressure gas valve ensures normal operation even with a low gas pressure of 3.5" of water column.
Automatic Water Filling System
→ Automatically fills the space heating pipes with water when the unit senses water shortage.
Internal Circulation Pump Included
→ Primary circulation pump and air vent for added value and convenience
Powerful Anti-Freeze Feature
→ Built-in Control System prevents the water inside unit from freezing in winter under most non-severe conditions.
Backlit LED Front Panel Command Center
→ Allows you to adjust the hot water temperature and boiler functions such as outdoor reset curves, heating setback, low water safety control, output capacity, and water fill pressure.
• Easy setup
• User friendly interface
• Convertible display from °F (Fahrenheit) to °C (Celcius)
• Cascade operation status display
• Temperature and water flow rate indicator
→ ASME, AHRI, CSA. NSF/ANSI 372 for Low Lead (DHW only). SCAQMD Rule 1146.2 Type 1 which complies with 14 ng/J or 20 ppm NOx at 3% O2.
|Space Heating Specific Specs|
|Space Heating Gas Input, MBH||12,000-60,000||14,000-80,000||18,000-100,000||18,000-120,000|
|Heating Capacity, MBH
(US DOE test procedures)
Net AHRI Rating, Water, MBH
|AFUE (annual fuel utilization efficiency)||95%|
|Water pressure (hydronic)||12 to 30 PSI|
|Heating Supply/Return Connection||1" NPT|
|Domestic Hot Water ("DHW") Gas Input||12,000-120,000 BTU/H||14,000-150,000 BTU/H||18,000-180,000 BTU/H||18,000-199,900 BTU/H|
|Flow Rate that results in a 77°F (43°C) water temperature increase||2.6 GPM (9.8 L/m)||3.4 GPM (12.9 L/m)||4.0 GPM (15.1 L/m)||4.5 GPM (17.0 L/m)|
|Dimensions||17"(W) x 28"(H) x 12"(D)|
|Product Weight||66 lbs (30kg)||74 lbs (34kg)||84 lbs (38kg)||84 lbs (38kg)|
|Installation Type||Interior Wall-Hung|
|Venting Type||Forced Draft Direct Vent|
|Water Pressure (DHW)||15-150 PSI|
|Natural Gas Supply Pressure (from source)||3.5"-10.5" WC|
|Propane Gas Supply Pressure (from source)||8.0" to 13.5" WC|
|Natural Gas Manifold Pressure (min to max)||-0.08" WC to -0.34” WC||-0.07" WC to -0.66” WC||-0.05" WC to -0.36" WC||-0.06" WC to -1.2" WC|
|Propane Gas Manifold Pressure (min to max)||-0.08" WC to -0.30" WC||-0.06" WC to -0.62" WC||-0.1" WC to -0.66" WC||-0.03" WC to -0.98" WC|
|Minimum Flow Rate (DHW)||0.5 GPM (1.9 L/m)|
|Maximum Flow Rate (DHW)||5.6 GPM|
|DHW Inlet/Outlet Connection||3/4" NPT|
|Gas Inlet Connection||3/4" NPT|
|Auto Feeder Connection||1/2" NPT|
|Condensate Outlet Connection||1/2" NPT|
|Main Power Supply||120V AC, 60Hz|
|Maximum Power Consumption||200W (up to 2 amps)|
|Casing||Cold Rolled Carbon Steel|
|Heat Exchangers||Stainless Steel Primary, Secondary, and DHW Heat Exchanger|
|Exhaust Venting||2” or 3" PVC, CPVC, Polypropylene 2” or 3" Special Gas Vent Type BH (Class II, A/B/C)|
|Intake Venting||2” or 3" PVC, CPVC, Polypropylene 2” or 3" Special Gas Vent Type BH (Class II, A/B/C)|
|Vent Clearances||no required clearance distance to combustibles|
Water Temperature High Limit Switch, Ignition Operation Detector,
Installation & Operation Manual
User's Information Manual
Quick Installation Manual
Wall Mounting Bracket
Tapping Screws & Anchors
NG to LP Conversion Kit
2" Vent Termination Caps
2" Wall Flanges
Pressure Relief Valve for Heating
Spare Parts (fuse, etc.)
FAQ (Frequently Asked Questions)
Q1: What is the difference between the NCB-240 and the NCB-240E?
A1: The NCB-240E has five differences: It has an added integrated air vent on top of the internal circulator to purge air from the boiler system, a pressure release valve ("PRV") on the top of the unit (back left side), a Grundfos recirc pump, a quieter fan, and a more appealing, beveled design on the front cover.
Q2: I would like to buy this Navien heater to replace another water heater that uses metal vent pipe. I read the manual that describes various PVC products to use for venting. The manual does not state that metal should not be used. Are there any performance issues if I use my metal exhaust vent pipe and not the PVC type pipe?
A2: You should only use your metal venting if it is stainless steel. Otherwise the corrosive liquid byproduct of gas combustion will destroy most other types of metal (galvanized and aluminum). Alternatively, you could install the PVC inside the metal venting, using the metal venting as a chase (like a conduit).
Q3: Does the NCB-240E ship from the factory configured for natural gas or propane?
A3: It comes configured for natural gas with an easy conversion kit to liquid propane included. Instructions: Gas Conversion Guide.
Q4: Are there separate heat exchangers for domestic hot water and radiant heat zones? Which heat exchanger has priority?
A4: The primary heat exchanger is used for heat (boiler function). The separate flat-plate heat exchanger is for DHW. The DHW function does have priority over heat in the combi units.
Q5: Is a remote control available for the NCB-240E?
A5: There are no wired remote controls available from any manufacturer for the NCB-240E. However, you may want to consider the NaviLink wireless control system which will control the NCB-240E.
Q6: Can I use my existing, standard thermostat with this boiler? I have only one zone baseboard heaters. My thermostat has only 2 wires.
A6: Yes, many customers have used their existing 2-wire thermostat with new Navien NCB combi boilers. This is normal.
Q7: I see that this unit has a Grundfos pump inside. Is it for moving water through my hydronic space heating pipes? Or is it for the domestic water heating recirculation line? Will the pump supply flow to an air handler?
A7: The internal Grundfos pump is used only to circulate water inside the unit only. It cannot be used for circulating water outside of the unit. To provide flow outside the unit, a primary pump is needed. And if you have zones, a zone pump/valve for each additional zone is needed.
Q8: Can I use a glycol mix in the radiant loop with this combi-boiler? I believe the radiant loop and running water output are not mixed, but wanted to be sure.
A8: Correct, the radiant loop and domestic water heating output are completely isolated, and you can use a glycol mix in the hydronic radiant loop.
Installation Help and Recommendations
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Alternate model number spelling: NCB240E
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