NCB-240/130H ultra-high efficiency combi-boiler

NCB-240/130H premium features and benefits

2" PVC venting up to 65 feet including economical schedule 40 PVC.Vent Installation Detector (VID) for added safety.

Dual Venturi system creates better combustion control and turndown ratio and easy field gas conversions.

Dual stainless steel heat exchanger-c-new

Durable dual condensing stainless steel heat exchangers recover extra heat for maximum efficiency.

Advanced user interface with Setup Wizard is made easy with backlit panel, click-wheel control and intuitive text.

1/2" gas pipe capability up to 24' (subject to local codes). Cuts installation time, no need to install new gas lines for retrofit applications.

Easily accessible built-in DHW module includes integrated boiler pump, flow adjustment valve, DHW stainless steel heat exchanger, mixing valve and 3-way valve.

NCB-240/130H QuickFacts

Dimensions

17.3" W x 29.3" H x 12.8" D (43.9cm W x 74.4cm H x 32.5cm D)

Overhead view of NCB-240/130H combi-boiler

Bottom view of NCB-240/130H combi-boiler

NCB-240/130H combi-boiler diagram legend

Certification Summary

Product approvals

CSA: Yes
SCAQMD 1146.2(NOx, <20ppm): Yes
Low Lead(<0.25%, DHW only): Yes
ASME Certified: Yes "H" Stamp
AHRI Number: 205400818
Energy star certified: Yes

Space Heating Ratings

AFUE, %: 95.0
Heating Capacity: 120,000 BTU/h (35.2 kWh)

DHW Flow Rates

DWH Temp Rise	NCB-240/130H
35 °F (19.4 °C) rate	10.4 GPM (39.4 l/m)
40 °F (22.2 °C) rate	9 GPM (34.1 l/m)
45 °F (25 °C) rate	7.9 GPM (29.9 l/m)
50 °F (27.8 °C) rate	7.2 GPM (27.3 l/m)
55 °F (30.6 °C) rate	6.6 GPM (25 l/m)
60 °F (33.3 °C) rate	6 GPM (22.7 l/m)
67 °F (37.2 °C) rate	5.4 GPM (20.4 l/m)
70 °F (38.9 °C) rate	5.1 GPM (19.3 l/m)
77 °F (42.8 °C) rate	4.7 GPM (17.8 l/m)
80 °F (44.4 °C) rate	4.5 GPM (17 l/m)
85 °F (47.2 °C) rate	4.2 GPM (15.9 l/m)
90 °F (50 °C) rate	4 GPM (15.1 l/m)
100 °F (55.6 °C) rate	3.6 GPM (13.6 l/m)

Gas Input Ranges

Model	NCB-240/130H
Heating	13,000 - 130,000 BTU/h (3.809 - 38.09 kWh)
DHW	13,000 - 199,900 BTU/h (3.809 - 58.571 kWh)

Applications

For NCB-H technical drawings of specific installations and requirements please visit NavienInc.com

Temperature Setting Ranges

Item		Temperature Setting Range
Space Heating	Supply	77 - 185 °F (25 - 85 °C)
Space Heating	Return	68 - 158 °F (20 - 70 °C)
DHW		86 - 140 °F (30 - 60 °C)

Actual supply and return temperatures vary depending on the selected outdoor reset curve.

Ratings

Navien Combination Boiler Space Heating Ratings
Model¹		NCB-240/130H
Heating Input	Min	13,000 BTU/h (3.8 kWh)
Heating Input	Max	130,000 BTU/h (38.1 kWh)
Heating Capacity²		120,000 BTU/h (35.2 kWh)
Net AHRI Rating, Water³		104,000 BTU/h (30.5 kWh)
AFUE², %		95.0
Other Specifications
Water pressure	Min	12 PSI (0.8 kg/cm²)
Water pressure	Max	30 PSI (2.1 kg/cm²)
Water Connection Size (Supply, Return)		1"

Navien Condensing Boiler Domestic Hot Water Ratings
Model¹		NCB-240/130H
Input Ratings	Min	13,000 BTU/h (3.8 kWh)
Input Ratings	Max	199,900 BTU/h (58.6 kWh)
Other Domestic Hot Water Specifications
Water pressure	Min	15 PSI (1.1 kg/cm²)
Water pressure	Max	150 PSI (10.5 kg/cm²)
Minimum Flow Rate		0.5 GPM (1.9 l/m)
Flow Rate 45 °F (25 °C) Temp Rise		7.9 GPM (29.9 l/m)
DHW Connection Size (Supply, Return)		3/4"

¹ Ratings are the same for natural gas models converted to propane use.

² Based on U.S. Department of Energy (DOE) test procedures.

³ The net AHRI water ratings shown are based on a piping and pickup allowance of 1.15.

Consult Navien before selecting a boiler for installations having unusual piping and pickup requirements, such as intermittent system operation, extensive piping systems, etc.

Specifications

Item		NCB-240/130H
Dimensions		17.3" W x 29.3" H x 12.8" D (43.9cm W x 74.4cm H x 32.5cm D)
Boiler weight		96 lbs (43.5 kg)
Boiler Weight With Water		102 lbs (46.3 kg)
Installation location		Indoor wall-hung
Venting type		Forced draft direct vent
Ignition		Electronic ignition
Natural gas supply pressure (from source)		3.5 " WC to 10.5 " WC (0.87 kPa to 2.61 kPa)
Propane gas supply pressure (from source)		8 " WC to 13.5 " WC (1.99 kPa to 3.36 kPa)
Natural gas manifold pressure (min-max)		-0.06 " WC to -0.24 " WC (-0.015 kPa to -0.06 kPa)
Propane gas manifold pressure (min-max)		-0.06 " WC to -0.26 " WC (-0.015 kPa to -0.065 kPa)
Connection sizes	Gas inlet
Power supply	Main supply	120V AC, 60Hz
Power supply	Maximum power consumption	Up to 15 amperes
Materials	Casing	Cold-rolled carbon steel
Materials	Heat exchanger	stainless steel
Venting	Exhaust	2" or 3" PVC, CPVC, approved polypropylene 2" or 3" special gas vent type BH (Class III, A/B/C) 2" or 3" stainless steel
	Intake	2" or 3" PVC, CPVC, polypropylene 2" or 3" special gas vent type BH (Class III, A/B/C) 2" or 3" stainless steel
	Vent clearances	0" to combustibles
Safety Devices		Flame Rod, APS, Ignition operation detector, water temperature high limit switch, exhaust temperature high limit sensor, water pressure sensor, burner
Temperature setting range		86 - 140 °F (30 - 60 °C) (up to 0 °F ( °C) when setting the parameter)

Navien reserves the right to change specifications at any time without prior notice.

NCB‑H Videos

NCB-240/130H Featured Reviews

NCB-240/130H FAQs

What is a combi-boiler?

A combi (combination) boiler is designed to heat a building, using hot water (similar to a boiler), but also includes the components and controls to internally heat the domestic hot water (DHW) required in the application. By having both heating and hot water in one unit, the combi will save space in the mechanical room and also save on the initial installation compared to separate appliances.

How does a combi-boiler work?

A combi (combination) boiler provides both space heating and on demand domestic hot water. In heating mode, water from the space heating system will flow through the heat exchanger and out to the system similar to a standard boiler. When a domestic hot water demand (open faucet) occurs, water flows through a separate heat exchanger in the combi, and a valve inside the unit diverts heating water over to the DHW heat exchanger. Space heating water is used to heat the domestic hot water until the demand ends. At the end of the domestic demand, the combi will switch back to supply space heating.

Does the same water that heats the home come out the faucets?

Inside the combi-boiler is a heat exchanger that separates the space heating flow from the domestic water flow, so the water in the heating system is isolated from the domestic hot water. The only thing that happens in the heat exchanger is that the heat from the higher temperature space heating water is transferred to the lower temperature domestic water.

What's the benefit of choosing a combi-boiler?

Since the combi boiler provides both space heating and domestic hot water all in one unit, it can provide space savings over two or more units. Combi boilers also can provide endless hot water in DHW mode, similar to a tankless water heater. Combi boilers may also reduce the installation cost by reducing the number of appliances, possibly reducing the number of wall or roof penetrations required for exhaust and intake piping, and may reduce some of the gas piping requirements.

Does a combi-boiler require special installation?

Combi-boilers do not require any additional requirements, compared to a condensing boiler and water heater. Compared to installing two different appliances, the installation may even have fewer requirements.

Will my house freeze if I take a long shower?

When a DHW (hot water) demand happens in a Navien combi boiler, the unit switches from space heating mode over to DHW mode. Referred to as DHW Priority, the unit will utilize the full capacity to heat the domestic hot water until the flow stops, providing endless hot water. While in DHW priority mode, the space heating is disabled. Even with a long shower or extended DHW run time, the home may lose a few degrees, but the chances of the home freezing during that time are extremely low.

What size combi-boiler do I need?

The heating size of the boiler is determined by calculating the heat loss of the building, which is based on the size of the structure, the insulation value of the surfaces, and the door and window sizes. Since combi boilers also provide domestic hot water, the flow demand of the hot water fixtures also needs to be calculated to determine the maximum DHW flow required. A combi boiler size is chosen by ensuring that the unit can satisfy both demands. Typically with a combi boiler, the BTU input will be higher for the DHW demand than for the heating load. A qualified contractor can perform a heat loss and help recommend a proper boiler size.

Where do I locate the Serial Number of my unit?

Please see the following attachment on where you can locate your serial number.

1. Locating Serial Number

What are the terms of Navien's labor warranty?

The applicable period for this labor allowance for all water heater models is One (1) year from the effective date.

The payment and amount of any payment are subject to approval at Navien’s sole discretion.

The labor allowance will be paid based on Navien’s schedule of labor allowances.

I am a homeowner and have a problem with my unit. If I call technical support, can they walk me through troubleshooting my unit?

Because our product involves water, electricity, and gas, there is only a limited amount of troubleshooting that can be done with a homeowner/end-user.

We recommend contacting your original installer or a Navien Service Specialist (NSS) to troubleshoot the unit.

NOTE: Charges will apply for service calls outside of 1 year labor period and/or non-warranty issues. Please see terms of our labor warranty.

Does Navien have Field Technicians available to service my unit?

Because our product involves water, electricity, and gas, there is only a limited amount of troubleshooting that can be done with a homeowner/end-user. We recommend contacting your original installer or a Navien Service Specialist (NSS) to troubleshoot the unit. NOTE: Charges will apply for service calls outside of 1 year labor period and/or non-warranty issues. Please see terms of our labor warranty.

I think there is a part that needs to replaced, how do I get a new part shipped out to me?

If you feel like there is an issue with your unit, please have someone contact Navien Technical Support while in front of the unit with your Serial Number ready. We recommend that a license contractor, original installer, or NSS contact is the person who calls us, so we may do in depth troubleshooting to determine if there is a part failure.

Navien Technical Support will be unable to send out parts without registration of product (Serial Number, Date of Installation, Homeowner Information, and Installer Information).