Demand-type or instantaneous water heaters, another name for tankless water heaters, only provide hot water when it is actually required. They can be cost-effective since they don’t produce the standby energy losses that storage water heaters do. You may learn the fundamentals of how they operate here and decide whether a tankless water heater is a good fit for your house or not.
Without a storage tank, demand gas hot water system instantly heat water. When a hot water faucet is opened, cold water enters the appliance and passes through a heat exchanger, where it is heated by a natural gas burner or an electric element. Tankless water heaters thus provide a steady flow of hot water. There is no need to wait for a storage tank to have enough hot water in it. The output of a tankless water heater, however, restricts the flow rate.
Typically, tankless water heaters can produce 2 to 5 gallons (7.6 to 15.2 liters) of hot water per minute. Tankless water heaters powered by gas have higher flow rates than those powered by electricity. However, there are times when even the largest gas-fired model is unable to provide enough hot water for numerous simultaneous usage in large houses. A tankless water heater may reach its limit, for instance, if you take a shower and run the dishwasher at the same time. You can install two or more tankless water heaters to solve this issue. For equipment in your home that require a lot of hot water, such a clothes washer or a dishwasher, you can also install separate tankless water heaters. However, adding extra water heaters will increase the cost, which might not be worthwhile.
Demand water heaters can also be used for the following purposes:
- hot tubs or bathrooms far away
- appliance booster for machines like dishwashers and washing machines
- a system booster for solar water heating.
Demand water heaters can be 24%–34% more energy efficient than typical storage tank water heaters for residences that utilize 41 gallons or less of hot water per day. For homes that consume a lot of hot water — roughly 86 gallons per day — they can be 8%–14% more energy efficient. If a demand water heater is installed at each hot water outlet, you can in some situations be able to save even more energy.
A tankless water heater is more expensive to acquire initially than a traditional storage water heater, but they often live longer and have lower operating and energy costs, which may make up for their higher original cost. The majority of tankless water heaters have a lifespan of over 20 years. They also feature pieces that are simple to swap out, which might add many more years to their lifespan. Storage water heaters, on the other hand, endure 10 to 15 years.
The standby heat losses associated with storage water heaters are avoided by tankless water heaters. Gas-fired tankless water heaters have better flow rates than electric ones.