For today's fast-paced, dinner-in-an-hour kitchens, hot-water dispensers
are the epitome of convenience, accelerating all kinds of kitchen tasks:
preparing hot drinks, soups, gelatin, sauces and cereals; thawing juices;
pre-heating water for cooking; warming baby bottles; even melting wax or
purging berry stains from clothing. Though top-of-the-line models may cost
$400, you can buy serviceable units for as little as $100.
Instant hot-water dispensers are simply miniature electric water heaters
that serve only one faucet. A small, under-sink tank heats and holds nearly-boiling
water, ready for steamy delivery through a sink-top spout that's separate
from the main tap.
Unlike a conventional water heater, however, the tank never becomes pressurized.
The system hooks up directly to a cold-water pipe under the sink; incoming
water travels first through the body of the spout then into the tank where
it's heated by an electric coil. The heated water expands, filling an expansion
chamber in the upper part of the tank. When you turn on the faucet, more
cold water is released into the bottom of the storage tank, displacing hot
water in the tank and expansion chamber and forcing the heated water up
through the faucet.
The spout delivers water slower than a typical faucet does--about one ounce
per second --and the water is much hotter than a standard hot-water tap's:
about 190 degrees instead of 120 degrees. The heated water arrives immediately;
you don't have to wait for it to warm up.
An adjustable thermostat --factory set at 190 degrees-- controls water temperature
with most models. Adjustment is needed only if the water is too cool or
if it's so hot that it boils away, causing the tank to overheat. (To prevent
damage, the tank should be protected from overheating by a replaceable,
thermal fuse.)
Tanks vary in size and by the heating elements' wattage. Most are 1/3 or
1/2 gallon and range from 500 to 1300 watts. A 750-watt, 1/2-gallon tank
will produce up to about 60 cups of hot water per hour; higher wattage tanks
can deliver up to 100 cups per hour.
How much does it cost to keep the hot water ready and waiting? According
to Bryce Dreeszen, Marketing Manager of In-Sink-Erator, the industry's largest
manufacturer, "The usage is a little more than 1/2 kilowatt hour per
24 hours which, depending on your local electric rate, equates to about
6 or 7 cents a day. "
As will any water heater, hot-water dispensers may accumulate scale in hard
water areas. Some units have drain plugs at the bottom to allow you to drain
the tank once or twice a year.
--Don Vandervort
