Set the water heater to 120°F
The Consumer Product Safety Commission and NFPA recommend 120°F: hot enough, and far less risk of scalds.
Who: You can do it yourself. Tank models. Electric thermostats sit near live wiring, so the breaker goes off first; the utility will set it for you if you’d rather.
How often: Once. For: the water heater.
Safety first
- Electric: turn the breaker off before removing the panels.
- 120°F is not scald-proof: 5 minutes can still burn. Test the water by hand before bathing an infant.
What you need
- A candy, meat or kitchen thermometer.
- A screwdriver, for electric panels.
- A marker.
How to do it
- Which kind is it: gas (a dial or buttons on the gas valve), electric with two thermostats behind two panels, or electric with a digital control?
- Mark where it’s set now.
- Aim for 120°F. Higher (140°F) only with a mixing valve at every tap, for bacteria; at 140°F a scald takes 5 seconds.
- Gas: set the dial to the 120°F symbol.
- Electric with panels: breaker off, remove the upper and lower panels, and set both thermostats to the same setting. Digital control: set it from the control panel as the manual shows.
- Test: first thing in the morning, or 2 hours after any hot-water use, run the farthest hot tap for 3 minutes and read the thermometer.
- Too hot? Turn it down, wait (a couple of hours to a full day), and test again.
- Mark the new setting.
If yours is a tankless or heat pump unit
Set it on the unit’s display, as its manual shows.
If you’ve been away 2 weeks or more
Before using any electrical appliance, open the kitchen hot tap for several minutes: hydrogen can build up in the tank.
Normal
- A gas heater that sizzles or puddles for a few minutes after it is first lit: condensation; it stops.
Needs attention
- Water far hotter than the setting, or a lot of hot water from the relief-valve pipe: the tank is overheating. Turn the power off.
Call a plumber if
- Overheating, as above.
Keep track of it
Add your home to My homes: each piece of equipment gets this on its own schedule, with “Mark done” and reminders you can turn on.
Sources
Where the makers differ:
- 120°F is what CPSC, NFPA, the Department of Energy, State and Energy Trust give; Rheem says 120-125°F.
- A. O. Smith’s symbol is “approximately 120°F” and its preferred starting point; Bradford White ships at about 120°F and says not to start above the “HOT” (120) mark.
- How long to wait before testing again: Energy Trust says a couple of hours; NFPA, a full day.
Your owner’s manual comes first: where it says something different for your model, follow it.
Still stuck?
Email us at hello@tradewrench.com. Tell us which page you were on and what you were trying to do.