Storage Water Heater Vs Tankless Water Heater: Which is the Best?

• A storage water heater is a device that contains a storage tank to maximize heating capacity and provide instantaneous delivery of hot water.

• Tankless water heater is a device that heats the water instantaneously and simultaneously as it is being used.

• Storage water Heater is also called Storage tank water Heater.

• Tankless water heater is also called instant water heater or demand type water heater.

• In Storage Water Heater, water is first filled in the tank and later heated. It requires time to heat the water i.e. hot water is not instantly available. If it is an electric heater, you will have to switch on before you use it.
• When water gets heated up to a specific temperature, the thermostat will sense the water temperature and further heating of water shall stop automatically.
• Only the quantity of water that the tank can accommodate is heated, i.e., the quantity of hot water available would depend on the capacity of the heater.
• Once the hot water in the tank is used, the tank gets refilled, and water is heated again in it. This process requires time

• In Tankless Water Heater, the incoming cold water enters through the inlet, passes through a heat exchanger in which it gets heated, and hot water is instantly available at the outlet.
• The switch has to be turned off to stop the heating of incoming water.
• Once the hot water is used, the incoming water is heated instantly, and thus, hot water is available continuously.

• It consists of thermally insulated storage tank, thermostats (temperature sensitive device), pipes and heating elements (either electric heating or gas burners).

• It consists of a switch, small pressure vessel with a heat exchanger and a pilot lamp (a lamp that lights up when circuit is closed). The heater is to be switched off immediately after use, hence no thermostat is required.

• CO₂ emission is more.

• CO₂ emission is less.

• As compared to Tankless water heater, efficiency of storage water heater is less.

• Life span is 10 to 12 years.

• Life span is about 20 years.

• Suitable for large establishments.
• They are available in variety of sizes.
• The flow (quantity of water coming from the tap) and the velocity (the speed at which water comes) is acceptable. Hence, it is better for use and provides adequate flow.
• If there is more than one bathroom in a house, it reduces capital costs.

• Continuous hot water flow is available.
• It does not generate standby energy (heat) losses.
• Water quality is not affected because water is not stored.
• Water is not contamination as it is not stored in the heater.
• Suitable for small establishments.
• Heat loss is less due to short pipe length for the conveyance of hot water.

• Continuous hot water flow is not available.
• Hot water stored in the tank continually loses heat.
• These heaters affect the quality of water due to the storage of water in tanks.
• Hot water flow is available as soon as the hot water tap is turned on. Of course, this is possible after the initial heating, which may take time between 10 to 20 minutes depending upon its capacity.
• If the temperature of hot water reduces below 60° C, water stored in the tank gets contaminated due to the breeding of bacteria.
• More pipelines causes heat loss during conveyance of hot water from the storage water heater to the fixture.

• Exchanger first builds up the temperature, and later the hot water comes out. This process may take a couple of minutes or more.
• The flow and velocity both are comparatively lesser than the storage water heater and hence it is not suitable where enormous quantity of hot water is required.
• It is not suitable as water flow is not adequate.
• A gas geyser befits more than one bathroom, i.e. there is no need of separate geyser in each bathroom. Whereas in case of electric geyser, separate electric geyser is required for each bathroom.

• Capital cost i.e. initial cost is more.

• Capital cost is less but more power is used in case of electric geyser. Gas geysers are cheaper than electric geysers.

• Electricity
• Gas
• Solid Fuel (wood, coal, biomass, charcoal)
• Sunlight – (Solar Energy)

• Electricity
• Gas

• These heaters are recommended as per the capacity i.e. minimum amount (gallons/liters) of hot water a geyser can deliver. Eg: A 30 gallon storage heater will store and yield 30 gallons (114 L) of water. One may choose the geyser depending upon the family size. Make choice of heater accordingly.
• First Hour Rating (FHR) is taken into consideration. It is the number of gallons of hot water the heater can supply per hour (starting with a tank full of hot water). More FHR means more quantity of hot water available.
• Always choose more efficient (more stars) water heater.

• Theses heaters are recommended on the basis of quantity of water required at fixtures. Normally this is the water quantity required for various domestic purposes.
• Add the GPM of fixtures in use and make the choice of heater accordingly.

For Example: If a user has a shower, washing machine and a sink, he should prefer (3.0+2.0+1.5 = 6.5GPM) capacity water heater.

• Gallons per Minute rating (GPM) i.e. quantity of water flow available per minute is taken into consideration.
• Eg: A 6.5 GPM water heater will deliver 6.5 gallons (25L or 1 bucket) water in 1 minute.
• Always choose more efficient (more stars) water heater.