Both residential gas and electric water heaters come in a variety of sizes but the most common are:

• 40 gallon
• 50 gallon
• 66 gallon
• 75 gallon
• 80 gallon
• 120 gallon

The majority of homes have a 40 or 50 gallon tank with the 50 gallon tank being the most common.  Larger tanks such as a 66 or 80 gallon tank are usually only used for very large homes or for homes that have a large soaking tub or jacuzzi. 

It is possible to upsize or downsize your water heater.  Customers are often interested in installing a larger tank if they have recently installed a large soaking tub.  When upsizing to a larger tank, we will ensure that your entire system is installed safely and typically this will entail increasing the size of the vent on gas water heaters.  Larger tanks emit a larger volume of carbon monoxide and as a result, must have a larger vent in order to be safely installed.  We can also check space requirements with you over the phone to ensure that a larger tank will fit.  Occasionally a customer will choose to downsize their tank as 66 and 80 gallon tanks are often more expensive than more common 50 gallon tanks.  We do not recommend downsizing from a 50 gallon tank to a 40 gallon tank, however, as 40 gallon tanks are typically comparable in price to 50 gallon tanks.   

Smaller Tanks are Also Available

There are a also a variety of smaller tanks used for special applications such as an under sink water heater (sometimes called a lowboy) and very small 2, 4, 6, 20, 25, 20 and 30 gallon tanks which are sometimes used as supplements to your water heater system or used as application-specific tanks.  Tanks of this size can be useful for a single sink or in same cases are used as an additional heater for a recirculation system.  Tanks of this size, however, are typically only available in electric powered and not gas powered.

How Do Tanks Compare in Terms of Efficiency and Hot Water Output?

Typically, there are four measures of how a hot water tank operates:

• Efficiency rating
• Recovery rate assuming the temperature is raised by 90° F
• 1st Hour recovery rate
• Estimated operating cost

Efficiency Rating

Efficiency rating is a measure of the percentage of heat transfer from the energy source to your water.  Standard electric tanks range from 88-95% efficiency while standard gas tanks range from 55-65% efficiency.  Electric tanks allow for higher energy transfer because electric tanks heat your water through heating elements which are submerged in the water, while gas fired tanks are heated from below through a gas burner. 

Despite higher efficiency ratings, typically electric tanks are more expensive to operate as the cost of electricity needed to heat your water is higher than the cost of gas needed to heat your water.  So, while heat transfer is more efficient in electric tanks, this does not mean that your overall energy usage is less in an electric tank.  Because of this, many utility companies and governments often encourage residents to use gas heating if choosing between gas and electric. 

Regardless, the higher the efficiency rating of your tank, the less energy is wasted in heating the water.