State default temperature is 120°F per industry standard. Adjust via the gas control knob (gas units) or the upper/lower thermostat dial (electric units).
Why 120°F default
- Scald safety: 120°F causes burn in 5-10 minutes; 140°F in 5 seconds
- Energy: every 10°F over 120°F adds 3-5% gas/electric use
- Sediment formation: higher setpoints accelerate scale
How to set on gas units
Rotate the dial on the gas control valve:
- "A" or "Vacation" = lowest setting (~95°F)
- "B" = ~115°F
- "C" = ~125°F (factory default region)
- "Very Hot" = ~140°F maximum residential
How to set on electric units
- Turn off the breaker
- Remove access panels for both upper and lower thermostats
- Set both thermostats to the same temperature (120°F default)
- Replace access panels
- Restore breaker
Both thermostats must be set to the same temperature; mismatched settings cause unpredictable performance.
Premier Hybrid heat pump temperature
Premier Hybrid units have a digital display panel with mode and temperature setting. Press the temperature button to adjust between 100°F and 150°F. Default 120°F.
When to deviate from 120°F
- Dishwasher needs 130°F: raise unit + install thermostatic mixing valve at fixtures
- Legionella concern in homes with infrequently used fixtures (raise to 140°F + TMV)
- Multi-person high-demand: 125°F to increase effective FHR
Bottom line
120°F unless an appliance forces higher. Always use thermostatic mixing valves at fixtures when raising the heater above 120°F.