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July 24, 2023

Installing a Navien Combi-Boiler

Navien high-efficiency combination boilers supply endless domestic hot water plus whole-home heating in one compact wall-hung appliance. Best of all, our combi-boilers don’t require any special installation procedures - in fact, installing a combi-boiler can be easier than installing both a water heater and a boiler separately.

Combi-Boiler Installation Cost

The cost of installing a combi-boiler in your home or business depends on several factors, including:

Whether or not there are already suitable venting pipes available

If you are replacing an existing combi-boiler or condensing boiler it will typically be a lower cost installation compared to installing a combi-boiler for the first time or replacing a non-condensing system.

How much gas & water piping needs to be installed

Your new combi-boiler will need to be connected to water and gas supply lines. Typically, installations tend be near other home mechanical systems, however when the installation site is farther from the main lines you can expect additional cost to add the required piping.

How complex the installation is

Are you replacing a heating boiler and traditional tank water heater with a combi-boiler? Expect additional cost to remove the inefficient, outdated equipment. The savings from installing a new high-efficiency combi-boiler will make up for the cost and you will enjoy the extra floor space. Installing a combi-boiler in a new construction or replacing an existing combi-boiler with a new one that uses the same connections will help lower installation costs.

Which installer you hire for the job

Because combi-boilers are connected to gas, electrical, and plumbing you’ll need a qualified professional to install your new combi-boiler. Different companies or contractors will have different hourly rates (this can be also affected by the region where you live). Navien always recommends using qualified contractors to ensure safety, properly program the heater, and understand how to service the heater.

How Long Does It Take to Install a Combi-Boiler?

As noted above, each installation job is unique and may have different requirements. If you’re replacing an existing combi-boiler using the same type of system and the same fuel source, a professional can probably complete the installation in a few hours. Converting to a new fuel source (for example, replacing an electric heating system with a gas combi boiler), relocating your combi-boiler to a different part of the house, or replacing a tank-style water heater and heating boiler with a combi-boiler are more complex and will take longer, based on your overall renovation plans. You’ll need to get an estimate from an authorized Navien installer to know for sure.

Navien Combi-Boiler Installation Diagram

This diagram shows supply connections (with dimensions) on the top and bottom of the NCB-H combi-boiler:

Navien combi-boiler installation diagram

A - Pressure relief valve adapter

B - Air intake

C - Exhaust gas vent

D - Heating supply

E - Domestic hot

F - Gas connection

G - Domestic cold

H - Auto feeder inlet

I - Condensate outlet

J - Heating return

The installation and user manual for each combi-boiler models includes multiple installation diagrams for various applications including:

  • Zone systems with pumps
  • Zone systems with zone valves
  • Air handler systems
  • Air handler systems with RS-485 communication
  • External recirculation mode with dedicated return line
  • External recirculation mode with HotButton & dedicated return line

The manuals also include:

  • Wiring diagrams for several different examples of electrical connections & system applications
  • Gas supply piping diagrams with different NG & LP piping examples
  • Direct, non-direct & common venting diagrams
  • Cascade system application diagrams (with or without recirculation)

Visit our product downloads page and select your model to view or download combi-boiler installation and user manuals.

Explore Navien’s NCB-H Series combi-boilers (residential only) and NFC-H Series combi-boilers (commercial or residential), learn how to choose the right size combi-boiler, or find a combi-boiler installer to get a quote for your project.

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