Water Heater Efficiency and Tips to Avoid Failures

For many years, residential water heaters were mainly stand-alone, tank-type devices that used either electricity or natural gas for the energy source. The average home typically had a 40-gallon tank of hot water always available for showers, baths, and dishwashing. Gas-fired water heaters were vented into a masonry chimney, along with the gas-fired furnace.

Many homeowners have converted from older tank-type to high-efficiency, on-demand water heaters. These units don’t have a storage tank, but heat the cold water instantly when needed, as it flows through the heater. State or utility rebate programs commonly offer financial incentives to upgrade to high-efficiency water heaters at the time of replacement. The incentives can offset the increased cost to switch from the low-efficiency unit to the high-efficiency system.

With many homeowners converting from tank-type to on-demand water heaters, it is important to compare the maintenance requirements for each type of system to prevent premature failure of equipment.

Common Maintenance Requirements for Tank-Type Water Heaters* 

  • Drain and flush the tank of sediment every six months
  • Inspect the venting system (gas) for obstructions, damage, or deterioration annually
  • Inspect the hot and cold-water connection pipes for signs of corrosion annually
  • Inspect the burner and pilot assembly (gas) for sooting and proper flame annually
  • Vacuum the dust, dirt, and lint from the area around the base of the tank as necessary
  • Operate the temperature-pressure relief valve annually
  • Inspect the anode rod every three years and replace if necessary

Common Maintenance Requirements for On-Demand Water Heaters* 

  • Clean the inlet water filter as needed
  • Inspect the venting system (gas) for obstructions, damage, or deterioration annually
  • Inspect the hot and cold-water connection pipes for signs of corrosion annually
  • Inspect the burner and pilot assembly (gas) for sooting and proper flame annually
  • Use pressurized air to remove dirt and lint from the area around the main burner, heat exchanger, and fan blades annually
  • Operate the temperature-pressure relief valve annually
  • Flush the heat exchanger of lime and scale using a circulating pump and vinegar solution for one hour based on trouble-code readouts

*Be sure to check the Installation and Operation Manual that was supplied with the water heater for the actual manufacturer’s maintenance requirements.

The high-efficiency, on-demand water heaters will provide increased efficiency and reduced operating cost because there is no tank heat loss during times when hot water is not needed.

CLICK HERE for more tips on water heater efficiency from the HSB Equipment Resource Center.

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© 2021 The Hartford Steam Boiler Inspection and Insurance Company. All rights reserved. This article is for informational purposes only and is not intended to convey or constitute legal advice. HSB makes no warranties or representations as to the accuracy or completeness of the content herein. Under no circumstances shall HSB or any party involved in creating or delivering this article be liable to you for any loss or damage that results from the use of the information contained herein. Except as otherwise expressly permitted by HSB in writing, no portion of this article may be reproduced, copied, or distributed in any way. This article does not modify or invalidate any of the provisions, exclusions, terms or conditions of the applicable policy and endorsements. For specific terms and conditions, please refer to the applicable endorsement form.


  • I really appreciate the section of your article that tackled the specific things you need to watch out for when maintaining an on-demand water heater. These are the units we use at home since we want to be as efficient as possible while letting most of our relatives live with us, and the increased use has gotten me to think about how we’re maintaining them. I’ll keep this in mind so we know what to ask from a plumber in the area when we hire them for unit inspections.

  • You got my attention when you said that the venting system must be annually checked for obstructions, damages, or deterioration as well the hot and cold-water connection pipes. This is something that I will consider because I am planning to have a water heater installed at home. My husband and I are planning to hire a professional that can have the system installed efficiently. Thanks!

  • My sisters’ water heater is starting to leak, and that is why she has decided to start looking for repair service. Well, I also agree with you that it would be best to hire an experienced HVAC contractor. Thank you for sharing here as well the importance of preventive maintenance.

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