Peak use, not average use

Households run out of hot water at their busiest moment: back-to-back morning showers, a bath while the dishwasher runs, or laundry on a weekend afternoon. A good sizing conversation starts there. How many people shower in the same hour? Are there large tubs, rain showerheads or body sprays? Does anyone run hot-water appliances at the same time?

Brea homes vary widely, from compact 1950s and 1960s tract houses to larger hillside and planned-community homes with more bathrooms. A heater that suited the original owners may be undersized after a remodel added a bathroom or a big soaking tub.

Ratings that matter

Tank capacity
The nominal gallons the tank holds. Useful, but not the whole story.
First-hour rating
How much hot water a tank heater can deliver in an hour starting full. Shown on the yellow energy label and a better guide than capacity alone.
Recovery rate
How quickly a tank reheats water. Gas burners generally recover faster than electric elements.
Flow rate (GPM)
For tankless units, the gallons per minute it can heat at a given temperature rise.
Temperature rise
How many degrees the heater must raise incoming water. Colder incoming water lowers tankless flow.

A simple way to think it through

  1. List your busiest hour.Count the showers, baths, dishwasher and laundry loads that happen in the same hour.
  2. For a tank, match the first-hour rating.Ask the plumber to compare your peak-hour need with the first-hour ratings of the models they suggest.
  3. For tankless, add up simultaneous flow.Add the flow of fixtures that run at the same moment and compare it with the unit's GPM at your temperature rise.
  4. Check the space.Measure height, width and clearances. A larger tank may not fit where the old one stood.
  5. Check the connections.Bigger gas input, venting or electrical load may mean upgrades.

Bigger is not always better

Going larger

  • More hot water for peak use
  • Heavier, taller tank that may not fit
  • More water kept hot when no one is using it
  • May need new venting or gas line changes

Staying the same size

  • Simplest swap with fewest changes
  • Fine if the old heater kept up when it was healthy
  • Check whether the old one lost capacity to sediment
  • A higher-recovery model can help without a bigger tank

Questions to ask

  1. What first-hour rating or GPM do you recommend for our household, and why?
  2. Will the larger model fit and vent in the existing space?
  3. Does upsizing change the gas line, vent or electrical requirements?
  4. Would a higher-recovery tank solve the problem without going bigger?

Common questions

What size water heater do I need?

It depends on your peak-hour use more than the number of people. Ask a plumber to match the first-hour rating of a tank, or the flow rate of a tankless unit, to your household.

Why does my new tank seem smaller than the old one?

Newer tanks may have thicker insulation and different dimensions, and recovery rates vary by model. Compare first-hour ratings rather than capacity alone.

Does a larger family always need a tankless heater?

Not always. A correctly sized tank with good recovery can serve a large household well. Compare both options for your space and connections.

General information for Brea, not a quote or professional advice. In an emergency, call 911.