Navien NFC-175 Fire-tube Condensing Combination Water Heater/Boiler
Navien's NFC-175 fire tube combination of boiler and tankless water heater
The NFC-175 packs an amazing array of advanced efficiency tech and features in one unit. You get:
• Patented stainless steel fire tube ASME Certified heat exchanger
It's the ideal solution for people who need both a space heating application and a domestic hot water heater.
Benefits of Hydronic Heating
→ Allergy sufferers rejoice! With hydronics, there is no forced air through vents, and meaning no dust creating or dry air blowing around.
The NFC-175 can be used in all of these hydronic heating applications:
♥ Baseboard heating
High turn down ratio reduces wasted energy and boiler cycling
→ The NFC's sophisticated gas flow control system provides a turn down ratio of 10:1 for heating and 10:1 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
Dual Stainless Steel Heat Exchangers
|NFC-175 (this page)||NFC-200|
|Space Heating Specific Specs|
|Space Heating Gas Input, BTU per hour||18,000-175,000||18,000-199,900|
|Heating Capacity, MBH
(US DOE test procedures)
Net AHRI Rating, Water Heating, MBH
|AFUE (annual fuel utilization efficiency)||95%|
|Water pressure (hydronic)||12 to 80 PSI|
|Radiant heating Supply/Return Connection||1.25" NPT|
|Domestic Hot Water ("DHW") Gas Input, BTU per hour||18,000-199,900|
|Flow Rate that results in a 67°F water temperature increase||5.4 GPM (20.44 L/M)|
|Dimensions||17.3"(W) x 33.3"(H) x 17.3"(D)
(43.9cm (W) x 85.1cm (H) x 43.9cm (D)
|Product Weight||145 lbs (65.8kg)|
|Weight with water||183 lbs (83kg)|
|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)||-0.05" WC to -0.47” WC|
|Propane Gas Manifold Pressure (min to max)||-0.1" WC to -0.45" WC|
|Minimum Flow Rate (DHW)||0.5 GPM (1.9 L/M)|
|Maximum Flow Rate (DHW)||5.6 GPM|
|Radiant heating Supply/Return Connection||1.25" NPT|
|DHW Cold Water Inlet 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||less than 15 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, Water Pressure Sensor, Ignition Operation Detector, Flame Rod, APS, Exhaust Temperature High Limit Sensor
Installation & Operation Manual
Gas Conversion Guide
Valuable Accessories Included FREE from GadgetsGo
√ NFC-175/200 manifold system (for single boiler)
√ NaviClean™ (part # GXXX001727)
√ 3/4" Isolation valve kit for DWH (part # 30009323A)
√ Pressure relief valve for radiant heating
√ NG to LP Conversion kit
√ Outdoor temperature sensor & cable (part # 30012950A)
√ System temperature sensor (part # GXXX001769)
√ Air vent
√ Air vent bushing (1/4" to 1/2")
√ PRV-Air vent adapter (including a clip)
√ Condensate trap
√ 2" Vent termination caps (x2)
√ 2" in-wall flanges (x4) (part # 30010747A)
√ Wall mounting bracket
√ Tapping screws & anchors (x2)
FAQ (Frequently Asked Questions)
Q1: 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?
A1: Yes, the reason for using PVC versus metal is for energy efficiency. Navien recommends using PVC because the NFC heaters are condensing type heaters. Using PVC provides the maximum condensing function. The Navien heaters will run more efficiently with PVC.
Yes, you could use your metal venting instead of PVC; the heater will still work safely. Alternatively, you could install the PVC inside the metal venting, using the metal venting as a chase (like a conduit).
Q2: Does the NFC-175 ship from the factory configured for natural gas or propane?
A2: It comes configured for natural gas with an easy conversion kit to liquid propane included. Instructions: Gas Conversion Guide.
Q3: Are there separate heat exchangers for domestic hot water and radiant heat zones? Which heat exchanger has priority?
A3: 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.
Q4: Can I use my existing, standard thermostat with this boiler? I have only one zone baseboard heaters. My thermostat has only 2 wires.
A4: Yes, many customers have used their existing 2-wire thermostat with new Navien NFC combi boilers. This is normal.
Q5: 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.
A5: 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
We recommend that you have a professional tankless water heater installer review the above recommendations. Improper installation may cause loss of life and/or property. Need an installer? Get 4 FREE Tankless Water Heater Installation Estimates Now. It's Quick and Easy!
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Alternate model number spelling: NFC175
Consumer purchases through the internet or other e-commerce channels shall void Navien's warranty. As with all products we sell, all Navien products we sell are brand new, recently manufactured ("factory fresh"). We guarantee delivery in perfect condition to our customers.
The NAVIEN and KD NAVIEN, and ComfortFlow trademarks are the property of Navien America, Inc. and/or KyungDong Navien.