Do your research. Know the type of water heater you want before yours stops working. We’re here to help you make an informed choice so you can rest assured you’ve made the right investment for your home and budget.
Infographic credit: Department of Energy
Tank Water Heater
Tank water heaters are the most commonly used type of water heating system in the United States. Most single-family homes use a tank water heater that utilizes a tank to maintain a ready reservoir of anywhere from 20 to 80 gallons of hot water. Basically, the tank of water is heated, and hot water is released from the top of the tank when you turn on the hot water tap. As hot water is used, cold water is pumped into the bottom of the tank and the pilot light cycles on, ensuring that the tank is always full of water and water is being heated.
Tank water heaters use natural gas, propane, fuel oil or electricity to operate.
Since water is continuously heated in the tank, energy is used even when a hot water tap isn’t running. This loss of heat is referred to as standby heat loss. Only tankless water heaters do not lose standby heat. Even the most insulated storage tank water heater models lose heat, requiring heating of the water. Tank water heaters fueled by oil and gas also have venting-related energy losses.
Tank water heaters last 10-15 years, and usually have lost a significant amount of efficiency by year 10.
Tankless Water Heater
Tankless water heaters heat water directly without the use of a storage tank. When a hot water tap is turned on, cold water travels through a pipe into the unit, and either a gas burner or an electric element heats the water. As a result, tankless water heaters deliver a constant supply of hot water. You don’t need to wait for a storage tank to fill up with enough hot water.
Tankless water heaters save between 30-35% of water heating costs. Even greater energy savings (up to 50%) can be achieved if you install a demand water heater at each hot water outlet.
The initial cost of a tankless water heater is more than that of a conventional storage water heater, but tankless water heaters last significantly longer and have lower operating and energy costs, which offset the higher purchase price. Most tankless water heaters have a life expectancy of more than 20 years. They also have easily replaceable parts that extend their life by many more years.
Heat Pump Water Heaters
Most homeowners who have heat pumps use them both to heat and cool their homes. However, a heat pump also can be used to heat water – either as stand-alone water heating system, or as combination water heating and space conditioning system.
Heat pump water heaters use electricity to move heat from one place to another instead of generating heat directly. Therefore, they can be two to three times more energy efficient than conventional electric resistance water heaters. To move the heat, heat pumps work like a refrigerator in reverse.
While a refrigerator pulls heat from inside a box and dumps it into the surrounding room, a stand-alone air-source heat pump water heater pulls heat from the surrounding air and dumps it — at a higher temperature — into a tank to heat water. You can purchase a stand-alone heat pump water heating system as an integrated unit with a built-in water storage tank and back-up resistance heating elements. You can also retrofit a heat pump to work with an existing conventional storage water heater.
Heat pump water heaters require installation in locations that remain in the 40º–90ºF (4.4º–32.2ºC) range year-round and provide at least 1,000 cubic feet (28.3 cubic meters) of air space around the water heater. Cool exhaust air can be exhausted to the room or outdoors. Install them in a space with excess heat, such as a furnace room. Heat pump water heaters will not operate efficiently in a cold space. They tend to cool the spaces they are in. You can also install an air-source heat pump system that combines heating, cooling, and water heating. These combination systems pull their heat indoors from the outdoor air in the winter and from the indoor air in the summer. Because they remove heat from the air, any type of air-source heat pump system works more efficiently in a warm climate.
Homeowners primarily install geothermal heat pumps — which draw heat from the ground during the winter and from the indoor air during the summer — for heating and cooling their homes. For water heating, you can add a desuperheater to a geothermal heat pump system. A desuperheater is a small, auxiliary heat exchanger that uses superheated gases from the heat pump’s compressor to heat water. This hot water then circulates through a pipe to the home’s storage water heater tank.
Desuperheaters are also available for tankless or demand-type water heaters. In the summer, the desuperheater uses the excess heat that would otherwise be expelled to the ground. Therefore, when the geothermal heat pump runs frequently during the summer, it can heat all of your water.
During the fall, winter, and spring — when the desuperheater isn’t producing as much excess heat — you’ll need to rely more on your storage or demand water heater to heat the water. Some manufacturers also offer triple-function geothermal heat pump systems, which provide heating, cooling, and hot water. They use a separate heat exchanger to meet all of a household’s hot water needs.
Unfortunately, heat pump water heaters are significantly more expensive than tank or tankless water heaters.
Solar Water Heater
Solar water heaters are a cost-effective way to generate hot water for your home. They can be used in any climate, and the fuel they use is free. Sunshine!
Unfortunately, the sun doesn’t always shine. Clouds get in the way. Solar water heating systems require a backup system for cloudy days and times of increased demand. Conventional storage water heaters usually provide backup and may already be part of the solar system package. A backup system may also be part of the solar collector, such as rooftop tanks with thermosyphon systems. Since an integral-collector storage system already stores hot water in addition to collecting solar heat, it may be packaged with a tankless or demand-type water heater for backup.
Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don’t. Solar water heaters are wonderful – if you can afford one. Talk with a water expert to see if this investment fits your budget.
Tankless Coil & Indirect Water Heater
Tankless coil and indirect water heaters use a home’s space heating system to heat water. They’re part of what’s called integrated or combination water and space heating systems.
Like the tankless water heater mentioned earlier in this article, when a hot water faucet is turned on, water is heated as it flows through a heating coil or heat exchanger installed in a main furnace or boiler. Tankless coil water heaters are most efficient during cold months when the heating system is used regularly but can be an inefficient choice for many homes, especially for those in warmer climates, because the furnace or boiler is not active most of the year.
Indirect water heaters are a more efficient choice for most homes, even though they require a storage tank. An indirect water heater uses the main furnace or boiler to heat a fluid that’s circulated through a heat exchanger in the storage tank. The energy stored by the water tank allows the furnace to turn off and on less often, which saves energy. An indirect water heater, if used with a high-efficiency boiler and well-insulated tank, can be the least expensive means of providing hot water, particularly if the heat source boiler is set to “cold start.”
Indirect systems can be fired by gas, oil, propane, electric, solar energy, or a combination of any of these. Tankless systems are typically electric, oil, or gas-fired. These water heating systems work with forced air systems and hydronic or radiant floor heating systems.
Neither of these systems are cost-efficient for Charlotte homes.
Need a Charlotte Plumber?
If you’d like to talk to a Charlotte water heater expert to understand your water heating options, give us a call. We’ll gladly discuss the pros and cons of a new water for your home or business.