Tankless water heaters, also known as on-demand water heaters or instantaneous water heaters, provide hot water only when it is needed. This can result in cost savings because there are no standby energy losses like with tank water heaters. Here’s some basic information on how tankless water heaters work, whether they’re right for your home, and what to look for when choosing a model.
How it works
Tankless water heaters heat water instantly without the need for a storage tank. When you turn on the tap, cold water flows through a heat exchanger inside the unit, and a natural gas burner or electric element heats the water. Tankless water heaters, therefore, provide a constant supply of hot water. There is no need to wait for hot water to come out of the storage tank. However, the output of water heaters is limited by the flow rate.
Tankless water heaters typically provide between 7.6 and 15.2 gallons of hot water per minute. Gas-fired water heaters have a higher flow rate than electric water heaters.
However, even the largest gas systems may not provide enough hot water for a large family using multiple water heaters simultaneously. For example, if the dishwasher and dryer are running while you shower, a tankless water heater may be pushed to its limits. To solve this problem, you can install two or more tankless water heaters.
Another tankless water heater can be installed for appliances that use a lot of hot water, such as washing machines and dishwashers. However, additional water heaters cost more and may not be worth the extra cost.
Read more about how to light a tankless water heater.
Other applications of on-demand water heaters include.
- Remote-controlled baths or whirlpools
- Boosters for appliances such as dishwashers and washing machines
- Boosters for solar water heaters.
Advantages and disadvantages
For households with daily hot water use of 41 liters or less, demand-controlled water heaters can be 24 to 34% more energy efficient than conventional water heaters. For households with high hot water use (approximately 86 gallons per day), they can be between 8 and 14% more energy efficient. In some cases, even greater energy efficiency can be achieved by installing a demand-controlled water heater at each hot water connection.
Although the initial cost of a tankless water heater is higher than a traditional storage water heater, the higher purchase price can be offset by the fact that tankless water heaters generally last longer and have lower operating and energy costs. Most tankless water heaters have a lifespan of 20 years or more. They also have easily replaceable parts that can extend their life by many years. In contrast, storage tank water heaters have a lifespan of 10 to 15 years.
Tankless water heaters do not have the same standby heat losses as storage water heaters. However, gas-fired water heaters typically have a higher flow rate than their electric counterparts, but can waste energy when a pilot light is present. This can be offset by the elimination of standby energy losses compared to storage water heaters. In gas water heaters, the pilot flame heats the water in the tank, so no energy is wasted.
The cost of running the pilot light in a tankless water heater varies from model to model. Check the manufacturer’s literature to determine the amount of gas used by the pilot light in the model you are considering. Look for models with an intermittent ignition device (IID) instead of a pilot light. This device is similar to the spark ignition device on some natural gas stoves, ranges and ovens.
Check out the best deals on tankless water heaters.
Installation and maintenance
Proper installation and maintenance of water heaters can optimize their energy efficiency.
Proper installation depends on a number of factors. These factors include the type of fuel, climate, local building codes, and safety considerations, especially those related to the combustion of gas water heaters. Therefore, it is best to hire a qualified plumbing and heating contractor to install your on-demand water heater.
When selecting a contractor, keep the following in mind
- Request written estimates
- Get references.
- Check the company out with your local Better Business Bureau.
- Obtain local permits, if necessary, and make sure the company is aware of local building codes.
If you intend to install the water heater yourself, contact the manufacturer first. The manufacturer usually has the necessary installation and operating instructions. Also contact your city or town for information on permits and local regulations for water heater installation, if necessary.
Regular maintenance of the water heater can significantly extend its life and minimize efficiency losses. Refer to the user manual for specific maintenance recommendations.
Improving energy efficiency
After properly installing and maintaining on-demand water heaters, try some other energy-saving options to reduce water heating costs. Some energy-saving appliances and systems are more cost-effective when installed next to the water heater.
Read about the best tankless gas water heater.