Water Tank Heater

How to buy the best water tank heater for your home. Explore the advantages, disadvantages and find the most popular sizes and manufacturers.

Tank water heaters are also known as storage tank type or cylinders. Gas water heaters with the storage tank are the most popular type for water heating in North America where 50-gallon capacity is the most used size.

With the available capacities from 20 gallons to over 100 gallons, water heater tanks are designed as the whole-house systems so they can supply more than one fixture at a time. Water storage tank heater is recommended for homes with the steady demands.

How tank-type water heater works

water tank heater from kenmoreTank of the heater is the place where hot water is stored and where the cold water enters. Incoming cold water is coming from the home plumbing through the inlet tube or dip tube to the lower part of the tank.

Water is heated either by the heating elements or gas burner and as becoming hot, it rises up from where it is going to the hot water tap (once it is open). Every gallon of hot water that exits the water tank heater is being replaced by the cold water through the dip tube. The thermostat is what signals the tank heater to start heating.


Tank water heaters are using gas, electricity and solar energy for heating. As opposed to the tankless heaters, storage-tank type is built very simple where the tank occupies most of the unit. Every WH, made of the metal has the anode rod, thermostat, dip tube, TPR valve and drain valve.

Gas powered storage tank heaters have also the gas valve, burner assembly, gas combustion chamber and the flue baffle (vent). FVIR system is found on all today's water heaters, which protects from the accidental fire of the flammable vapors. From the gas burner, through the tank and water stored inside, there is a flue tube that extracts the gases out, either naturally (atmospheric vent units) or forced (powervent units).

Most of the gas water heaters are using the pilot light for lighting the main burner, while other more advance are using hot surface, for example.

Electric heaters are the simplest units, that utilize the upper and lower heating element for heating the water.

Solar heaters are tanks that store heated water (from solar panels) with the addition of the heating elements for the back-up heating.

Oil powered WH


In North America there are three the most popular and biggest manufacturers of tank-type heaters:

Other manufacturers and brands such as:

are owned or build by Rheem, AO Smith or BW.

Tips when buying tank water heaters

  • Buy the energy efficient water heater or Energy Star approved. The EF (energy efficient) has to be 0.67 or higher. EF is what indicates how efficiently the heat is transferred to the water. Condensing WHs have the highest EF which can be more than 0.9. High efficiency water heaters are usually equipped with the heat traps and have thicker insulation or R value. For the heaters with the lower efficiency, it is recommended to use insulation blanket.

  • Buy a heater with the larger or more than one anode rods as such units have better warranty and are protected from corrosion longer.

  • For the family of four to five, 50-gallon tank size is sufficient. Use the following instructions for sizing a water heater.

  • If it is needed, look for the high First Hour Delivery and recovery rate, and low stand-by heat loss.

  • Gas heaters are a good buy as they have higher First Hour Rating than the electrical ones so you might need smaller unit for your water heating needs than the electric.

  • Look for the tank-type heater with the self cleaning system as it automatically fights the sediment build-up problem; also green or low NOx burner, high recovery, high performance or high efficient models.

The First Hour Delivery and other info can be found on the Energy-Guide label.

Selecting the right water heater

Selecting the right water heater means enough hot water for all family members, convenience and savings. This is what you should consider:

How big is your family?

How many applications (shower, dishwasher...) will be using hot water?

The usage pattern of your family members: frequent short or high-flow and high volume draws.

Calculate the peak demand or the busiest one-hour usage period based on the numbers from below:

An average gallons for shower is 20, for shaving 2 gallons, hands and face washing 4 gallons, food preparation 5 gallons, automatic dishwasher 14 and so on. So, if you have calculated that you need 50 gallons of hot water you would buy a 70-gallon water heater (70% is the available volume).

Tank water heater vs. tankless

  • Tank type has lower upfront cost - unit and installation costs are lower.

  • Smaller burner and heating elements.

  • Cheaper venting system.

  • No electricity required.

  • Tank-type heater has to deal with the stand-by heat loss as the water is heated when not in use and as it is losing the energy through the outer surface.

  • Gas tank-type heater provide hot water even during the power outages.

  • They are free standing therefore occupying a valuable floor space. Dedicated room is needed.

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