Gas vs Electric Tankless Water Heaters – What to Choose

How to choose a Tankless Water Heater

As you probably know Tankless water heaters can save you lots of money:

The only issue is which one to choose. You can compare tankless water heater  prices and read all the tankless water heater reviews, but how do you choose which water tankless heater is right for your household? What is better, natural gas, electric, or propane?

To choose a tankless water heater you need to know 3 things:

  1. What utility services are available for your home
  2. Your households water flow requirements
  3. The groundwater temperature for your region

Utility Service

If your home has gas and electrical service, you can choose whichever tankless water heater best suits your household’s needs. If your home doesn’t have natural gas, you will need to consider if an electric or propane tankless water heater will meet your household’s needs.

Household Water Use

The volume of water the unit is required to heat, measured as flow rate in gallons per minute (GPM). A tankless water heater is sized by rating its temperature rise at a given GPM. Estimate how much water you think will be used at the same time. For example, if you have a 1 person household, you are unlikely to have 2 showers running at the same time, but maybe you would like to be able to have the capacity to run the dishwasher(2.0GPM), washing machine(2.5GPM) , and shower(2.0GPM) at the same time. Each fixture will have a specific flow rate that you can look up. Our hypothetical household would choose a tankless water heater with a 6.5GPM rating. Obviously, the GPM need will be less for smaller households- less people means less water being used at the same time at once

Groundwater Temperature

One electric tankless water heater might be sufficient to heat a small household in Texas. The same household in Maine might need a higher capacity tankless gas water heater, even if they use the same amount of water. Why is this? The average person showers with 105˚F water. If the water entering your home is 70˚F, the water heater only need to heat the water an additional 35˚. If the beginning water temperature is 40˚F, the water heater will need to heat the incoming water 65˚, which uses much more energy. A colder temperature means your tankless heater needs to work harder to provide your water because it requires a greater temperature rise. A water heater can have a 5.62GPM flow rate at 35˚ rise and a 2.55 GPM flow rate at 77˚ rise. Households in cold climates should choose gas tankless water heaters because they have a greater heating capacity.

Let’s examine the pros and cons of the three types of tankless water heaters.

Propane Tankless Water Heater

Pros

  • Higher capacity then electric, up to 11GPM
  • Greater heating ability then electric
  • Available in rural areas, unlike natural gas

Cons

  • Propane is more expensive then natural gas
  • Needs to be vented properly, venting needs to be done correctly
  • Needs additional installation work at high altitudes to correct the lower oxygen levels in high altitude air. Otherwise, propane will not burn cleanly and could produce carbon monoxide.
  • If your home does not currently have propane service, you will need to get a tank installed and arrange for service.
  • Yearly maintenance recommended

Price Range- $499-$1900

Tips: Realize that even if you install a gas model, it must have electrical connections to operate the sensors and switches. These connections must also meet amperage and voltage requirements and may have to have a separate circuit breaker. Requires a minimum gas line size of 3/4-inch.

When is Propane a Good Choice?

  • A propane tankless water heater is a good choice if you do not have natural gas service.
  • This is typically applicable to rural areas.

Natural Gas Tankless Water Heater

Pros

  • Higher capacity, up to 10.6 GPM
  • Greater heating ability
  • More efficient than oil or electricity
  • Less expensive than oil or electricity
  • less likely to need upgrades to existing utility services

Cons

  • Needs to be vented properly, venting needs to be done correctly
  • Needs additional installation work at high altitudes to correct the lower oxygen levels in high altitude air. Otherwise, the natural gas will not burn cleanly and could produce carbon monoxide.
  • Yearly maintenance recommend

Price Range- $499-$1900

Tips: Realize that even if you install a gas model, it must have electrical connections to operate the sensors and switches. These connections must also meet amperage and voltage requirements and may have to have a separate circuit breaker. Requires a minimum gas line size of 3/4-inch.

When is Natural Gas a Good Choice?

  • Natural gas is a great choice for a whole house system.
  • Natural gas provides more heating and flow capacity then electric, so it can meet a large family’s needs and operate well in cold climates.

Electric Tankless Water Heater

Pros

  • Good for point of use
  • Boosts existing systems
  • Good for low use households
  • Less expensive
  • Little maintenance needed

Cons

  • Less heating/flow capacity: Maximum 4 GPM
  • Might need expensive electrical work to upgrade amperage, voltage and the circuit breaker
  • Not good as a whole house water heating system for large household or cold environments

Price Range-$175-$1223

Tips- Your house’s electrical set up must be able to provide adequate amperage, voltage and a circuit breaker, check with an electrician or your utility company before purchasing

When is Electric a Good Choice?

  • An electric tankless water heater is a good choice for homes in warmer climates and when the hot water demand is low, under 40 gallons a day. This would be applicable for a 2 adult household in Arizona or Florida.
  • Boosting hot water service to a remote location, like a guest house or pool house.
  • Boosting just one source, like a washing machine or hot tub
  • Boosting individual water sources in a large location, like a restaurant or grocery store.
  • Homes that do not have the option of natural gas.
  • Electric tankless water heater prices are generally a couple hundred dollars lower then gas or propane

Tankless water heaters can be an efficient, economical option for many homeowners. Overall, natural gas tankless water heaters are the choice for greater water heating capacity and electric models are better for small households and bolstering existing systems. Now that you have done your homework, you’ll be able to choose the right water heater for your family’s needs.