How to Know What Size Water Heater to Own

Just like any other home investment, choosing a new water heater requires extensive knowledge and research to help solve your problem quickly and affordably. The size you need is determined by your hot water using habits. For instance, a much larger tank is preferred by those who use three or more hot water appliances in the same hour.
If you regularly use a single hot water appliance during the same hour, you can go for a smaller tank. To understand the size of a water heater to own, let us first look at the different types of water heater you expect to find, their capacity and source of heat.

Types of Water Heaters

1. Demand-type or Tankless Water Heater

Tankless water heaters only deliver heated water when needed. Cold water is immediately heated by an electric element or a gas burner as it enters the unit. It doesn’t experience any standby heat loss since it lacks a tank with stagnant preheated water. This type can deliver at least 2 to 5 gallons per minute.

2. Conventional storage Water Heaters

These are some of the commonly used water heaters in most homes. It has the capacity to hold between 20 and 80 gallons and uses the electric element as a source of heat. Hot water is released from the top of the tank and then replaced by cold water from the bottom. Although it creates a reservoir of hot water, it is prone to standby heat loss.

3. Heat Pump Water Heaters

This type of water heater moves heat from place to place instead of generating heat directly. They are mostly used to heat and cool the home but also serves as a hot water system. Heat from an Air source heat pump water is derived from the air before it is transferred at high temperatures to a storage tank.

4. Solar Water Heaters

This type of water system heats water using roofed solar panels before it is delivered to a storage tank. You can make a choice between passive and active types of solar heating system. The passive solar system can either collect and store warm water at the top of your tank or preheat water in batch systems while cold water is held at the bottom. Active systems can either circulate non-freezing heat-transfer fluid through the collectors or directly circulate water into the home.

Factors to Consider When Choosing the Size of a Water Heater


Tall water heaters are often installed in garages or basements since they can easily accommodate their height. The space provided for the tall water heaters should also consider the required height of connecting a pipe on top of the unit to your home’s plumbing system.

Short water heaters are often wider and shorter than the normal hot water systems. This allows the heaters to fit in areas with limited headroom but still hold the same amount of water as the larger units. They can be installed under cabinets and crawl spaces.

First Hour Rating

First-hour rating is a type of measurement used to determine the amount of water you expect to be delivered by a water heater in one hour. It is always measured in gallons indicated at the top left the Energy Guide Label of your water heater. The first-hour rating is determined using a fully heated water tank.


One of the major factors to consider is the amount of water a storage water heater can hold in gallons. The best way is to get the right size is by determining the average amount of hot water you need. Short water heaters can hold up to 50 gallons of water and range between 30 to 49 inches in height. Tall water heaters have the capacity to hold up to 100 gallons of water and usually range between 50 to 76 inches


There are several accessories that help improve the safety and efficiency of your water heater. Some of them include expansion tanks, timers water alarms, water heated pans and stands. Extra tanks are often designed to carry the extra water volume produced when cold water in the tank is heated.

The size of the water heater to own may vary depending on your individual or family needs. It is important to have an idea of the type of tank you want to buy before considering the space, capacity and first-hour rating of the water heater. Whatever choice you make, always ensure that the selected size of water heater meets your specifications and requirements as well as the standard efficiency.