Tired of running out of hot water? Maybe it's time for a water heater
that has a greater capacity. But how "big" should it be?
Though the term "capacity" refers to a tank's size, the real capacity
of a water heater is a result of two factors: storage and recovery time
(how quickly it can heat a tankful of water). Conventional water heaters
range in tank size from 30 to 120 gallons; the most common sizes are from
40 to 75 gallons. (Short "lowboy" models are available in smaller
sizes.)
It's important to match size to your family's needs. If you get a tank that's
too small, you'll frequently find the water cooling down just about the
time you lather up in the shower. On the other hand, if you buy one that's
too large, you'll be paying more than necessary to keep the tank heated.
Needs can typically be measured by the number of bathrooms in the house,
though some circumstances can skew these standards-- a laundry-heavy family
with small children or a house with an especially large bathtub, for example.
Obviously, a couple living in a large house or a large family living in
a small house require adjusting the figures. Minimum size unit for a 1-bathroom
house should be 30 or 40 gallons, in either gas or electric. For a 1 1/2-bath
house, 40 gallons is minimum. For a 2- to 3 1/2-bath house, choose a 50-gallon
gas heater or a 66- to 80-gallon electric one (because electric water heaters
take longer to heat water, large tanks should be bigger than their gas-fired
counterparts). For a large, 4-bath house or a home with an extra-large bathtub,
get a 75-gallon gas heater or a 120-gallon electric heater.
Recovery of gas-fired water heaters is a function of the Btu input and overall
efficiency. Input ranges from about 32,000 on a 30-gallon unit to 88,000
on a 100-gallon tank. A common range is 34,000 Btus on a 40-gallon tank
and 36,000 Btus on a 50-gallon tank. The higher the Btu input and efficiency,
the faster the recovery. Electric water heaters typically have one 5500-watt
or two 4500-watt elements. Of course, two higher kilowatt elements heat
much faster than one lower-wattage element.
Both gas and electric water heaters are rated by the number of gallons they
can raise 90 degrees F in one hour. Most electric ones are rated from 20
to 25 gallons per hour; many gas units can recover more than a full tank--
a high-recovery 50-gallon Rheem gas model can recover up to 81 gallons per
hour. When buying a high-Btu gas model, be aware that it may require a 4-inch
flue rather than the standard 3-inch flue that probably currently exists
in your house.
--Don Vandervort
