Basically, a tankless water heater consists of a coil of tubing assembled in
a unit called a heat exchanger. In gas models, a main burner is situated
underneath the heat exchanger. In older models and some cheaper ones, a
standing pilot flame burns continuously to ignite the main burner upon a call
for hot water. Newer models use different sources of ignition: mechanical
ignition or piezo ignitors. In older models of tankless water heaters, the gas
valve provided a steady supply of fuel to the main burner irrespective of the
quantity of hot water required. This was, by and large, the source of
complaints about insufficient hot water volume. More hot water demand with
these older units meant cooler water temperatures and less hot water. Newer
models have a modulating gas valve. The greater the hot water demand, the more
fuel the gas valve supplies to the main burner. If you turn on the bathroom
sink faucet only using a small volume of water—about 1.5 gallons per minute—the
water heater’s main burner will only burn with a light, short flame. If you
turn on another hot water faucet, increasing the hot water demand, the main
burner flame will burn much hotter giving you more hot water.
Benefits of a tankless hot water heater.
Tankless water heaters can save you money. A tankless water heater without a
standing pilot will sit quietly doing nothing, not using any energy at all, not
using or heating water. If a tank type water heater springs a leak, you may be
faced with a flood and consequent water damage. Not so with a tankless water
heater; there is no tank full of water to drain out all over your floor.
Tankless water heaters are small in comparison to a tank type unit. They hang
on a wall and range in size from that of a bread basket to a large medicine
chest. Today many manufacturers make tankless water heaters. Some, like Rinnai,
make external models suitable for installation on the outside of your home.
Rinnai supplies a wall mounted thermostat that even has troubleshooting
capacity. You can set the temperature of your hot water from your bathroom or
anywhere else in your house with one touch of a button. You can install
multiple thermostats in different locations throughout your home. You can take
as long a shower as you want with a tankless water heater. It will produce hot
water without interruption as long as the hot water faucet is on.
To gain the greatest efficiency from a tankless water heater, carefully read
the installation instructions and owner’s manual supplied with the unit. All
current models operate on the principle of hot water demand. You will receive
the greatest benefit if you keep the water heater’s thermostat turned down and
avoid mixing cold water with the hot water flow to achieve the temperature you
desire. Tankless water heaters excel at filling hot tubs, jetted soaking tubs
and the like. Any application requiring large volumes of hot water is an
excellent candidate for a tankless water heater.