COVID-19 Update:

To protect the health of our staff and our customers, Efficiency Vermont offices are closed to the public. We have cautiously begun scheduling project related site visits when required. You can find more information on our safety protocols here.

We know that you need support in reducing energy costs now more than ever, and we will continue to launch new offers and programs over the course of the summer. In the mean time, our customer support team is available to help you remotely. Contact us at (888) 921-5990 or

Direct fired / storage water heaters

oil, natural gas, electricity, propane


Most common type of water heater. Storage tank water heaters have an insulated tank where water is heated and stored until it's needed. These are stand-alone systems that operate independently to other HVAC components such as a boiler.


  • Typically, the lowest purchase price of all water heater types
  • They typically have a reservoir from 30 to 50 gallons of hot water
  • Storing water in a tank means that it will experience standby heat loss, i.e. the preheated water loses heat that you have already paid to heat up
  • Purchasing a tank with better insulation holds that heat inside where you want it
  • Look for a high Energy Factor (EF) rating for the most efficient equipment

Heat pump water heaters



Not only do heat pump water heaters heat water, they also air condition and dehumidify the space around them.


  • They have a higher purchase price than traditional electric resistance water heaters, but heat pump water heaters can cost half as much to operate
  • They are sometimes called “hybrid” water heaters because they can switch to standard electric resistance heat automatically when hot water is in high demand
  • They are larger than conventional water heaters
  • They have slower recovery times than other types of water heaters and it is best to size them larger than you would normally
  • Requires a condensate pump
  • Because of their noise and cooling effect, they are best suited to basements or other non-living spaces
  • Some models have smart features such as leak detection with mobile alerts

Indirect water heaters

oil, natural gas, electricity, propane, solar energy


Also known as a “sidearm tank”, these systems utilize a boiler to heat a coil inside an insulated water tank. This heats up the tank of domestic water for later use. Indirect tanks therefore require a boiler to operate.


  • Indirect water heaters are most efficient during cold months when the heating system is used regularly
  • During warmer months, these systems can be very inefficient causing the boiler to run all year long and often heating up the area around the boiler
  • They utilize a storage tank
  • To optimize energy efficiency proper installation and maintenance of your combination water and space heating system is needed
  • We recommend having a qualified plumbing and heating contractor install it

On-demand water heaters

natural gas, electricity, propane


These water heaters operate as a stand-alone system, much as the direct-fired/storage tank systems. However, instead of storing hot water; they heat the water as it passes through a series of coils. Since the system only heats water as you use it, an on-demand heater is usually more energy-efficient than a traditional storage tank water heater and they produce unlimited hot water at a given output.


  • Also referred to as instantaneous water heaters
  • They don't have the standby energy losses associated with storage water heaters
  • More than one tankless unit maybe needed for large households
  • Electric on-demand units require very large power draws. Your home’s electrical service may not be adequate. Check with an electrician before installing

Solar water heaters

solar energy


Solar water heating systems include storage tanks and solar thermal collectors. Solar water heaters come in a wide variety of designs, all including a collector and storage tank, and all using the sun's thermal energy to heat water.


  • Solar water heating systems require a backup system for times of increased demand and less sun
  • They cost more to purchase and install than other conventional water heating systems but can save you money in the long run
  • Systems need to be properly designed and installed to optimize solar harvesting

Tankless coil water heaters

oil, natural gas, propane


These systems utilize a coil inside the boiler that heats up domestic water. Tankless coil water heaters are therefore fully integrated into the boiler and are often installed as a package.


  • Tankless water heaters are most efficient during cold months when the heating system is used regularly
  • During warmer months, these systems can be very inefficient causing the boiler to run all year long and often heating up the area around the boiler
  • Tankless water heaters provide unlimited hot water at a given output
  • These systems are inexpensive but can be one of the least efficient water heating types, which increases the operating costs of the water heater

Water heating is a home’s second-highest energy cost, so making a wise choice can lead to big savings later. Reach out to our customer support team for one-on-one advice about water heater options for your home or business.

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