Ruud default temperature is 120°F.
Why 120°F
- Scald safety
- Every 10°F over 120°F adds 3-5% energy use
- Higher setpoints accelerate scale on heat exchanger / tank
Gas tank units
Rotate the dial on the gas control valve:
- "A" / "Vacation" = ~95°F
- "B" = ~115°F
- "C" = ~125°F (factory default)
- "Very Hot" = ~140°F max residential
Electric tank units
- Turn off breaker
- Remove upper and lower access panels
- Set both thermostats to same temperature (120°F default)
- Replace panels, restore breaker
Professional Hybrid
Digital display panel. Press temperature button to adjust 100-150°F. Default 120°F.
Ultra Series Tankless
Digital controller. Up/down arrows. Range 98-140°F residential. Commercial override (180°F) requires installer service-menu access.
When to deviate
- Dishwasher needs 130°F: raise unit + install thermostatic mixing valve
- Legionella concern in homes with infrequent fixture use
- Recirculation loop temp loss: raise source to compensate
Bottom line
120°F unless an appliance forces higher. Use TMVs at fixtures when raising heater temperature.