What are the gas line and venting requirements for the Noritz NRC66DVNG Tankless Water Heater?

The Noritz NRC66DVNG requires a dedicated natural gas supply and a specific venting system designed for high-efficiency condensing units. Because this is a condensing model, it requires a condensate drain line in addition to standard gas piping and exhaust venting.

The Noritz NRC66DVNG provides a 6.6 GPM flow rate and is designed for natural gas use. Because condensing units produce liquid waste during the heat exchange process, you must have a condensate drain line nearby with the proper slope to prevent water backup. The unit uses Schedule 40 PVC pipe and fittings for venting. We selected this model for our comparison because of its high-efficiency rating and low NOx output. You must confirm that your existing gas meter has the BTU capacity to handle the unit’s peak demand and that your piping—whether black iron or CSST—meets the specific pressure drop requirements for a high-flow tankless system. If your current gas regulator is a standard residential model, it may require an upgrade or relocation to support the high-flow requirements of this specific heater.

Requirements to Verify Before Buying the Noritz NRC66DVNG

Before purchasing this indoor condensing tankless water heater, verify these technical requirements with a qualified installer to ensure your home can support the unit.

• Confirm your local municipality’s specific “Category IV” venting material requirements and required termination distances.
• Measure the physical clearance for the condensing exhaust path to ensure it does not hit structural beams or interior walls.
• Identify a nearby condensate drain location and confirm the required slope for the liquid waste line.
• Verify that your gas meter and regulator can provide the necessary volume to support a 6.6 GPM flow rate.
• Check if your existing gas piping diameter is sufficient to prevent pressure drops during peak operation.

Alternative Options for the Noritz NRC66DVNG

The Noritz NRC66DVNG is a high-efficiency unit suited for homeowners who prioritize low NOx emissions and a compact indoor footprint. If you do not have a nearby condensate drain or the specific venting clearance required for a condensing system, you should look at non-condensing tankless models instead. Non-condensing units often have different venting requirements and do not produce liquid waste, making them easier to place in homes with limited drainage access. Buyers with very high-volume demands who require more than 6.6 GPM should also consider larger commercial-grade units or multi-unit systems that offer higher flow rates.

If you need a broader range of options, see our top picks for the best natural gas tankless hot water heater.

If your home has a nearby condensate drain and you require a high-efficiency, low-emission system for your indoor space, the Noritz NRC66DVNG is a strong choice for your installation.