Noritz default output temperature is 120°F. Residential cap is 140°F. Commercial override extends to 180°F with installer enablement.
Why 120°F is the default
- Scald safety: 120°F causes third-degree burn in 5-10 minutes. 140°F does it in 5 seconds
- Energy: every 10°F over 120°F adds 3-5% to gas use
- Heat exchanger: higher temperatures accelerate scale formation on the ecoTOUGH heat exchanger
How to set
- Controller: up/down arrow buttons. Range 100°F to 140°F residential
- Remote controller (RC-9001 etc.): same range; some controllers have presets
- Commercial override (above 140°F): requires installer to enable via service menu. Intentional — Noritz limits residential units to 140°F as liability boundary
When to deviate from 120°F
- Dishwasher/laundry needs 130-135°F: raise unit to 135°F and install thermostatic mixing valve (TMV) at hot-water output to deliver 120°F at fixtures
- Legionella concerns in larger homes with infrequently used fixtures
- Recirculation loop temp loss — long loops drop 5-10°F; raise source to compensate
- Commercial sanitation: 180°F required for high-temp dishwasher sanitation rinse (restaurants)
NRCB combi — heating vs DHW temperatures
The combi units (NRCB180, NRCB199) have separate temperature settings:
- DHW output temperature — same rules as tankless units
- Heating supply temperature — separate setting, typically 130-180°F. Outdoor reset modulates based on outdoor temp
NCC commercial — cascade temperature behavior
The cascade controller sets a single target output temperature; all units in the cascade modulate to maintain it. Individual unit temperatures are slave to the controller. Commercial sanitation (180°F) is set at the cascade controller level.
Common temperature problems
- Water not hot enough at setpoint: scale on heat exchanger. See descaling
- Lukewarm at start of draw: cold-sandwich on standard NRC/EZ. Solve with EZTR upgrade or external recirculation pump
- Temperature swings during draw: low gas pressure, modulation issue, or undersized gas line
Bottom line
120°F unless a specific use case forces higher — then use a thermostatic mixing valve to deliver 120°F at fixtures for safety. Don't max the unit out as a general policy; you'll pay in gas and heat-exchanger scale formation.