Editor’s note: Originally published December 2020. Reviewed and updated November 2026. Some models mentioned here may have been updated or discontinued since; check current availability and specifications before buying.
The Noritz NRC661-DV-NG is an indoor, direct-vent, condensing tankless water heater that runs on natural gas and is rated at 6.6 gallons per minute (GPM). It is aimed at smaller homes: about two bathrooms in warmer southern climates, or one and a half in colder northern ones.
This review is based on the specifications and features listed by Noritz, not on hands-on testing.
Choosing a tankless water heater
Before picking a model, decide on type, fuel and size:
- Indoor or outdoor mount: outdoor units are best suited to warmer climates, since winter temperatures can get very cold.
- Fuel: natural gas, liquid propane (LP) or electric.
- Size: match the flow rate (GPM) to the number of fixtures you run at once.
Like other high-efficiency tankless models, the Noritz heats water only when there is demand, which helps save energy. For the broader trade-offs, see our tankless water heater pros and cons.
Noritz NRC661-DV-NG overview
When properly sized for the home and its demand, the NRC661-DV-NG provides continuous hot water, so you won’t run out halfway through a shower or need to wait for a tank to recover after someone else’s. Because there is no storage tank, there’s also no tank to fail and flood the floor, which is one advantage over standard tank water heaters.
Listed specifications
- Indoor mount only; direct vent; condensing
- Fuel type: natural gas
- 120,000 BTU
- Flow rate: 6.6 GPM
- Dimensions: 6.7 x 13.8 x 23.6 in
- Weight: 38 lb
- Vents with Schedule 40 PVC
Pros
- High-efficiency condensing design
- Continuous hot water when properly sized
- Vents with Schedule 40 PVC rather than costlier stainless steel
- Compact, quiet design
- Installation can be done by an experienced DIYer
Cons
- Delay before hot water arrives, as with any tankless heater without a recirculation pump
- Sized for smaller homes, up to about 2 bathrooms
- Indoor installation only
Installation
An experienced DIYer can install the NRC661-DV-NG, which may save significantly on labor. Read the installation manual first to make sure you have all the tools and materials you need. Gas, water and venting work is often covered by local codes and permits, so check your local requirements and hire a licensed professional if you’re unsure.
As an indoor model it must be vented through an exterior wall. The venting is Schedule 40 PVC, which is less expensive than the stainless steel venting some other brands require. Outdoor-mounted units can be easier to install because you don’t need to route an exhaust vent, although gas and water lines still have to reach them.
Bottom line
The Noritz NRC661-DV-NG is a solid choice for a smaller home with up to two bathrooms that wants efficient, on-demand hot water from natural gas. Its PVC venting and compact size make installation more straightforward. For larger homes, Noritz makes bigger models, and you can compare other options in our Rheem RTGH-95DVLN review and Takagi tankless water heater review.
