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Are you in the market for a new water heater and you are wondering which one to go for between short and tall water heaters? Whether you have moved to a new house or need to replace an existing water heater past its life, it is important to understand the different water heaters.

This article explores the difference, similarities, and operating mechanisms of short vs tall water heaters.

Difference Between Short and Tall Water Heaters

The main difference between short and tall water heaters is their size and capacity.

Tall Water Heater

A tall water heater is casually referred to among water heater experts as the “tall boy.” Typically, they have a height that ranges between 46 and 76 inches. They are cylindrical in shape with a diameter of 18 to 21 inches, and their water capacity ranges between 30 and 100 gallons.

Since they are significantly tall, they require ample space for installation for the heater and the plumbing pipes connected to the house. They are commonly installed in the garage or basement, where their height is easily accommodated.

The plumbing pipes are about 40 inches tall. If your basement or garage space is slightly less than needed to accommodate both the pipes and the heater, you can install the pipes diagonally to fit.

However, the heater itself and the main supply pipe attached on top of the heater have to be mounted in an upright position. Besides, a vertical alignment provides optimal water flow and decreased the risk for leakage and clogging.

Short Water Heater

On the other hand, the short water heaters, commonly referred to as the “low boys,” are wide and short. They are about 30-49 inches tall with a diameter range of 20-26 inches. They have a water capacity of 30 to 50 gallons, with the smallest ones having much less capacity of 20 gallons.

Due to their comparatively smaller size, they can be installed in smaller and crowded spaces such as crawlspaces or attics. The connecting pipes for short water heaters are usually 29 to 32 inches tall.

Similarities Between Short and Tall Water Heaters

Apart from their height, diameter, and size of their plumbing pipes, short and tall water heaters have a similar operating mechanism. Conventionally, they are tank water heaters. While some heat using electricity, others use gas. In some cases, a short or tall water heater can serve as a reservoir for hot water heated either by a solar heating system or a heat pump system.

Both can either be installed inside the house or in auxiliary spaces. Ideally, whether you choose a short or tall water heater, it should be installed close to the entire house’s plumbing system

Factors to Consider When Choosing Between a Tall and Short Water Heater

When choosing between a short and tall water heater, the main factors to consider are how much space you have for installation, your capacity needs, and your preference.

Measuring Your Installation Site

Before going on the market to buy a short or tall water heater, the first step is to determine what dimensions you are working with. Determine the installation site and, with a tape measure, take the height of the space where the heater and plumbing pipes would be installed.

Then, measure the width of the space to determine what diameter of heater would fit. Note whether there is any space left on the top and sides to allow room for easy access, proper ventilation, and pressure release.

Compare the measurements you get against the standard range of dimensions for tall vs short water heaters to determine which one is best suited for you. If you are not sure about which type of water heater to install, consult with a professional plumber.

The site you choose should be dry with no water leakage on the surrounding surfaces as these could lead to the water heater rusting and breaking down earlier than its expected life span. Also, there should be 30-40 inches allowance between the heater and the surface on top for ventilation and maintenance.


Tall water heaters are ideal if you have a high output of hot water. For instance, in a home with more than three members and where the heater will be supplying water to many fixtures at a time, a taller water heater would be ideal. On the other hand, short water heaters work best if your demand for hot water volume is low, for instance, in a studio apartment.

Energy Bills

Whether you have an electric heater or gas or propane heater, energy consumption is higher for taller water heaters as they have a higher power rating. Short water heaters are generally more energy-efficient as they have a lower power rating. They also heat the water faster than the tall ones due to the lower water volume in the storage tank.

How to Determine Whether Your Water Heater Is Short or Tall

If you already have a water heater and do not know whether it is short or tall, you can determine it by checking the heater’s specifications or measuring. If checking the specifications, look for the serial number label on the heater and check if it has the capacity indicated.

If you have the product’s manual, check the product dimensions that are provided therein. Otherwise, take the width (diameter) and height dimension measurements using a tape measure.

How Do Short and Tall Tank Water Heaters Work?

Whether your water heater is short or tall, the operating mechanism is the same. In a nutshell, the contemporary tank water heater has a tank, motor, and heating mechanism. The tank holds water while the motor gets heated either using gas or electricity, and the heat is transmitted to the water in the storage tank.

The storage tank holds the heated water until there is a need to use it, then it is let out through a valve into the pipes and out through the open hot water fixture(s). The water tank’s indicated capacity is the maximum amount of water the storage tank can hold.

How to Tell if Your Water Heater Is Powered by Gas or Electricity

It is simple, and you can do it yourself. However, before you start, ensure that the heater is powered off to prevent burning accidents. Open the access panel. It is usually located on the side of the heater. If you see gas pipes, then the heater is gas or propane powered; otherwise, it is electric powered if you see heating elements.

An electric water heater uses up to two replaceable heating elements. They are less expensive, highly efficient, and have a capacity of 30 to 100 gallons and above. Gas water heaters use a burner; therefore, they have an open flame when heating.

They need enough ventilation room to prevent overheating and should not be installed near flammable materials or items. They are more expensive upfront but use less energy in the long run compared to an electric water heater.

Which Is Better: Short vs Tall

Generally, a tall water heater is the best option if:

  • Your hot water runs out frequently
  • The volume of hot water flowing out is considerably low if you open several fixtures at a time
  • You use hot water in your washer or dishwasher
  • Your home hosts more than three people
  • You have ample space for installing both the unit and plumbing pipes while leaving enough space on top and the sides for accessibility and ventilation.
  • You do not mind a higher energy bill

Conversely, a short water heater is the best option if:

  • You have a lower demand for hot water
  • You live in a small house, and you have limited installation space
  • Your home has less than three occupants
  • You are keen to save up on energy bills

Accessories for Short and Tall Water Heaters

Below are some features and accessories to look out for when shopping for a water heater, regardless of whether it is short or tall. These features improve either the efficiency or safety of the heater. If your best choice for a water heater does not have these features, you could buy them separately and have a professional install as long as the parts are compatible with the particular model.


A timer comes in handy if you are keen to save on your energy costs. Once installed, you can set a specific time when the heater begins to heat water. This accessory works best for electric water heaters and is installed on the electrical supply line. Some timers are

Wi-Fi compatible so that you can operate them remotely


Most water heaters have an inbuilt thermostat that regulates the heater depending on the water temperature. However, it is also important to connect the heater with an external thermostat that sets off the heater if the surrounding temperatures exceed a given range.


A water alarm is used to detect any leakages. It is usually mounted either on the floor beneath the heater or the side and comes on if it comes to contact with water.

Heater Blanket

A heater blanket reinforces heat insulation in cold seasons, especially if the heater is installed in cold sites. It improves energy efficiency by enabling the heater to retain more heat, reducing your energy bill.

Water Heater Pans

They are installed below or on the side of the heater. Their main purpose of a drain pan to collect water that may leak or overflow from the heater. The pan has an opening on the side that allows the collected water to flow into drainage. This mitigates the risk of flooding in a scenario where there is too much water leaking from the heater.

Dry Fire Protection

This feature prevents the upper part of the heater from burning up in incase the heater is on, and there is no water in the tank. It is compatible with most electric heaters.

Water Heater Stands

They are mostly used with a  gas water heater. The stand raises the heater above the ground, reducing the risk of fire should a flammable liquid spill near the heater. If considering this accessory, factor in its impact on your installation site choice as you will need more space to accommodate it.

There are a lot of considerations to make when choosing a water heater. There are two main options to choose from when it comes to size. As discussed in this article, tall heaters are ideal for larger spaces where the demand for hot water is high, and there is enough space for installation.

On the other hand, short heaters are ideals for small spaces. Once you have determined the best size option, then you can choose between a gas water heater and an electric hot water heater. To improve on energy efficiency, go for a heater that has compatibility with accessories such as a timer, alarm, or blanket.