Perhaps this should be filed under “Duh!” but… I finally got around to going under the house and adjusting the thermostat on our new water heater. We’ve been noticing that our hot water isn’t lasting nearly as long as it did with our old water heater even though it has the same sized tank.
Why isn’t our hot water lasting as long? Mostly because water heaters are installed with the thermostat’s set to a factory default of 120°F, which is lower than what many homeowners prefer. Manufacturers do this in the name of safety — i.e., to minimize the risk of burns — but it also means that you’ll empty your tank much more quickly.
If you bump your water heater thermostat up a few degrees (check the owner’s manual for instructions), you’ll be able to mix more cold water into the stream while still achieving the same temperature. This means that you’ll use less hot water, leaving more in the tank of your water heater for other uses.
No, this isn’t the most energy-efficient approach, but if you have a large family, you might be willing to make that sacrifice. Just be sure to warn everyone in the family about the change, and don’t turn the temperature so high that you burn yourself!
A couple of alternatives to making your hot water last through multiple showers, baths, dish washing, laundry, etc. would be to insulate your water heater and (especially) your hot water pipes, install a low-flow shower head so you use less hot water when showering, or install a tankless water heater to produce hot water in real-time, on an as-needed basis.