Where to buy

The installation cost will vary based on the size and type of model you select, and whether gas lines need to be installed or replaced. Contact a local authorized Navien installer to request a cost estimate.

Every installation is unique and has several factors affecting how long it takes, including location, removal of the old water heater(s), and connecting the power, water, and gas lines. Your installer can provide a time and cost estimate after seeing the space.

The maximum vent length when using 2-inch approved vent pipe is 75 ft (23 m). The maximum vent length when using 3-inch approved vent pipe is 150 ft (45 m). The intake and exhaust vent pipes can be terminated either horizontally or vertically, using one of the multiple approved vent termination types. The maximum vent length is reduced according to the number of elbows used, so best results, the tankless water heater’s venting system should be kept as short and straight as possible. Exhaust and intake air pipes must be supported at least every 4 ft (1.2 m). Refer to the installation manual for additional details.

Some customers want to install a Navien combi-boiler but only use it for domestic hot water due to the season, or to replace a failing water heater before you’re ready to plumb in to the hydronic heating system. Navien combi-boilers are intended solely for use in pressurized closed loop heating systems, so the combi-boiler must be properly filled with water, air-free, be able to maintain constant pressure on the heating side even if you only want to use it for hot water. To do this, an external loop must be connected to the boiler supply and return connections, using field supplied piping or the Navien manifold system. The boiler safety relief valve, air separator, expansion tank, and make up water must also be connected. The combi will then operate in the domestic hot water mode until the heating system can be completed and properly connected.