Water Heaters

How Water Heaters Work

Whenever someone turns on a hot water faucet, heated water is drawn from the top of the tank and is replaced by cold water that is carried to the bottom through the dip tube. When the water temperature drops, a thermostat activates the heat source (a burner in a gas model -- two heating elements is an electric.) A gas heater has a flue running up the center and out the top to vent deadly gasses. An electric heater needs no venting. In both, an anti-corrosion anode attracts corrosion that would otherwise attack the tank's walls.

Inside a Water Heater

If you were to cut a water heater in half, you would find that it looks something like this (electric on the left, gas on the right):

A gas water heater is nearly identical to an electric water heater, except that it does not contain the two heating elements, but instead has a gas burner at the bottom, with the chimney running up through the middle of the tank.

A water heater consists of the following parts, as shown in the figure above:

A heavy inner steel tank that holds the hot water

Typically, this tank holds 40 to 60 gallons. It has to be able to hold the pressure of a residential water system, which typically runs at 50 to 100 pounds per square inch (psi). The tank is tested to handle 300 psi. The steel tank normally has a bonded glass liner to keep rust out of the water.
Insulation surrounding the tank
A dip tube to let cold water into the tank
A pipe to let hot water out of the tank
A thermostat to control the temperature of the water inside the tank (Many electric water heaters have a separate thermostat on each element.)
Heating elements to heat the water (These are the thick electric elements similar to those you see inside an electric oven.)
A drain valve that allows you to drain the tank to replace the elements or move the tank
A pressure relief valve (This is an important safety feature that keeps the tank from exploding.)
A sacrificial anode rod to help keep the steel tank from corroding

Important Water Heater Metrics

First-Hour Rating (FHR). FHR measures how much hot water will be available during the busiest hour of the day. A large tank does not necessarily translate to a higher FHR. The recovery rating is important as it indicates the water heater’s ability to replenish hot water as it is drawn from the tank.
Efficiency. The water heater’s efficiency is measured as an Energy Factor (EF), which is usually listed beside the EnergyGuide label. The higher the number, the more energy efficient the water heater.

How to Choose a Water Heater

Heating water accounts for approximately 15 percent of a home’s energy use. High efficiency water heaters use 10 to 50 percent less energy than standard models, saving homeowners money on their utility bills. Actual energy savings from high efficiency water heaters depend on family size, heater location, and the size and placement of water pipes.

At Mervin Zimmerman, Inc. we will help you to make the best water heater choice for your home. If you are looking for a lower purchase cost, then we will show you products from Bradford White which include high performance gas and electric water heaters. Another option, is a future money saver - a heat pump water heater from GeoSpring. There are benefits to purchasing an Energy Star heat pump water heater such as:

Big savings. ENERGY STAR qualified heat pump water heaters can save the average household almost $300 per year on its electric bills compared to a standard electric water heater. That's enough money to go on a weekend getaway every year. Larger families — that typically use more hot water — will save even more!
A smart investment. While a qualified heat pump water heater costs more upfront, the savings will pay back the difference in about three years. Replace your aging electric water heater before it fails, and start enjoying the savings right away.
A purchase that protects the environment. If everyone buying an electric water heater this year chose an ENERGY STAR qualified heat pump model instead of a standard model, we would avoid 19.6 billion pounds of carbon dioxide emissions. That's the equivalent of taking 1.6 million cars off the road.