Water heating represents between 14% and 25% of the energy used in your home. Selecting the right hot water heater impacts not only the comfort of your family but your energy usage for years to come.
To purchase the right hot water heater for you and your family, there are four major factors you will want to take into consideration – the type of fuel used to heat the water, the capacity of the hot water heater you will need to meet your family’s hot water usage, the efficiency of the hot water heater you select and the costs associated with the system you are considering.
Fuel- The two most common fuels for water heating are gas and electricity with propane and fuel oil also being used in some areas.
Capacity- When purchasing a hot water heater, you will want one that meets the needs of your family’s hot water usage. Most of us would look to the size of the hot water tank, but what is most effective is to look at its peak hour demand capacity. On a tank’s Energy Guide Label, you will see a First Hour Rating (FHR) number. What this represents is how much hot water that heater will deliver during a busy hour. As an example, a hot water heater you look at could have a tank capacity of 50 gallons but have an 82 FHR. This means it will deliver 82 gallons of hot water in an hour. Gas hot water heaters have a higher FHR than electric water heaters with the same water storage capacity. So if you are using gas to heat your water, you may be able to use a heater with a smaller storage tank. Estimate your family’s hot water usage during the busiest hour of your day to determine what is best for your needs.
To estimate how much hot water you will need in a busy hour, here are some averages available from the U.S. Department of Energy to help you. A shower takes an average of 15 gallons of hot water, while a bath will take 20 gallons. Washing clothes uses 32 gallons of hot water in an hour compared to your dishwasher which uses 14. Other routine tasks such as food preparation, shaving and washing your hands use anywhere from 2 to 5 gallons of hot water.
Efficiency – The fuel efficiency of your hot water heater is measured by what is called the Energy Factor or EF which measures thermal losses from the tank. The higher the EF, the more efficient the hot water heater. The average EF ratings by fuel source are
Gas .05 to .05
Electric .07 to .95
Oil .07 to .85
Heat pumps 1.5 to 2.0
This information can be found in the literature from the water heater’s manufacturer or from your dealer.
Cost – When comparing costs between water heaters, you will want to take into account three things – the initial cost of the heater itself, its ongoing maintenance and the annual energy costs to heat the water. The ongoing maintenance can be measured by its warranty, and the Energy Guide Label will provide an estimate of its annual operating costs. On the average, a hot water heater lasts 13 years. Look at all of these factors over that over that period of time to develop an accurate comparison between the hot water heaters you are considering.
Types of Hot Water Heating Systems
There are several water heating technologies on the market today.
Conventional hot water heating is a system which stores the heated water in a tank and is the most common type of hot water heater you will see in homes today. The tank can range from 20 to 80 gallons and operates by the hot water being drawn of the top of the tank what a faucet is turned on. Cold water then enters the bottom of the tank to be heated, ensuring the tank is always full. With this type of system, energy can be lost because the tank is constantly being heated, whether a hot water faucet is turned on or not.
Demand or tankless hot water heaters heat and deliver hot water when it is needed, not store it in a tank. This is done by a heating device that is activated by the flow of water when a hot water faucet is turned on. The capacity of a tankless system is measured by how many degrees the water temperature increases at a given flow rate. These systems are available in gas, electric or propane models. They come in models which heat water for your whole house or smaller units designed to supplement or boost other hot water heating systems.
Heat pump hot water heaters extract heat from the air (inside and outside) and deliver it to the water. While these save energy costs on an ongoing basis, their installation costs are significantly more than the other systems. This is where a careful comparison of all costs, both initial and ongoing, is important to your decision making.
Solar hot water heaters typically work in conjunction with another hot water heating system. By using the sun’s energy to either heat the water itself, or the energy from the solar system heats the water, the water is stored in a tank. If additional heating is necessary, it is provided by a conventional hot water heating system. By having the solar hot water heater system be the primary provider of heat, your hot water heating costs could be reduced by as much as 80%.
Hot water heating systems are not glamorous or all that interesting, but by taking the time to select the right unit for you and your family, you can have the comfort of hot water whenever you need it while saving energy usage and costs.