Water Tank Heaters

Storage tank sizing guide, cleaning, removing and flushing

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Water tank heaters, also called storage, stand alone and conventional water heaters are very popular in North America. If you own a house or condo, you are probably renting one 40 or 50 gallons tank-type heater, like I do from Reliance (my Rheem power vent came with a condo), and for a monthly charge. Or you can buy one from a few hundred dollars up to few thousands for the best models. This is what you will find in this article...


Guide to water tank heaters

This article is not about what model is the best, but it focuses on how conventional, water tank heaters work, types, benefits, sizing, tips and how to do cleaning, draining and flushing, and much more.

Gas, electricity or solar?

If it is feasible to use natural gas in your home for heating and storage tank type is what you are looking for, gas water heaters are probably the best option. If the natural gas is supplied to your house, great, if not, propane or LPG is good as the replacement.

And with the rising awareness about "green" technology and renewable energy, solar heating with solar tanks is also a good choice. Especially, because of the fact that the solar energy is free and governments provide great rebates, stimulation and help.

Alternative to the above fuel types are less popular, but still greatly used; oil fired burners, wood and electricity.

water tank heaters from AO Smith

Every water tank heater, no matter what fuel type is used, requires a special technical room, closet or a garage for its installation.

The capacity of the conventional tank-type heaters is usually in a range from 20 to 100 gallons and the most popular are 40, 50, 60 and 80 gallon tanks as they produce enough hot water for the standard family size from 4 to 6 members. These are known as the whole-house units.

Small size tanks of only few gallons, like the electrical heaters Ariston from Bosch are mainly for point-of-use applications.

When replacing a tank-type heater use the name-plate found on the heater to collect necessary information, including the capacity, insulation R-value, pressure rating of the tank, wattage and voltage of the electric heating element or BTU for gas unit.

Yellow tag is the energy guide label that shows the yearly costs of your heater.

How does a hot water tank work?

Conventional water tank heaters are very simply designed, usually standing on the floor in vertical position. The main part is the storage tank usually made of metal, where hot water is stored and drawn for the shower, bath, dishwashing or washing machine. For better heat retention metal tank is enclosed in foam insulation with the thickness from 1 to 3 inches and having different R-value (higher better).

Cold water enters at the bottom of the storage tank through the dip tube and soon after it is heated by the gas burner or electric heating elements, hot water rises to the top of the tank. Whenever using hot water, it is replaced with cold at the bottom through the dip tube. See what are the main components found in electric and gas water heaters.

Standard tank water heaters are designed simple so installation and troubleshooting are easy. Access panel at the front of the tank heater is conveniently positioned so replacing any faulty part is worry-free.

Types of water tank heaters based on the fuel source

  • Oil fired heaters

emergency plumber


Here is the list of the popular brands/manufacturers of the HVAC equipment, including water tank heaters, in North America:

  • American

  • AO Smith

  • Bradford White

  • GE or General Electric

  • John Wood

  • Kenmore

  • Marathon

  • Whirlpool

  • Reliance

  • Rheem

  • Richmond

  • State

  • Tips to save money

    • If you have a traditional tank-type water heater, by replacing it with the energy efficient heater you will definitely save on the long run.

    • Or, if it is feasible, consider solar storage water heaters.

    • How to check is your tank water heater wasting energy? Put your hand on the outside surface of the tank and if it feels warm your unit needs better insulation. If you install the insulation blanket or "jacket", standby heat loss will be reduced and you will save some money; like energy efficient units with thicker foam insulation. If you are considering buying a new unit, choose one with the higher R, insulation value (24 will be the best).

    • There is a lot of heat and energy wasted when waiting for hot water to reach the tap. Insulate all the pipes and you will reduce the energy loss.

    • If you lower the temperature on water heater thermostat by few degrees you are on the right way to save. Lower the temperature on your thermostat by one degree for an eight-hour period and you will reduce the energy consumption by one percent. The recommended temperature is between 120-140 degrees F.

    • To save money on your bill, our suggestion is to buy high efficiency water tank heater as they can perform as much as 40 percent better than conventional models.

    Note: Do you know that the average life expectancy of the heater is 13 years?

    How to select hot water tanks - what you should know

    The capacity, First Hour Rate, Recovery rate and energy efficiency are the most important factors when selecting the water tank heaters for home use. Other features might also be of your interest, and they include the advanced system such as self-cleaning, diagnostic system, intelligent gas control valve, LED display, hot surface ignition, flue damper, power or direct venting and other.  

    Choose the right tank size, but don't select an oversized heater, as the energy cost increases. If you are not sure, ask plumber or HVAC technician for the advice. Here is the sizing guide.

    Hot water delivery capability or First Hour delivery is a combination of a tank capacity and its recovery rate or how much hot water it can produce in one hour.

    High efficiency water heaters are more expensive but it pays off faster, and it usually comes with higher quality, efficient energy use and better warranties. High efficiency heaters are also environment friendly.

    The efficiency of gas, propane, and oil-fired water heaters is measured by an energy factor (EF). Higher - better.

    Electric water heater's efficiency is measured by standby loss or rating watts loss. Low-better. More about water heating here.

    For additional help, here are the buying guides for water tank heaters from Home Depot and consumerreports.org.

    (All pictures are courtesy of AO Smith)

water heaters