Consider purchasing a tankless water heater!

July 22, 2009 at 6:41 am 2 comments

tankless water heaterConventional water heaters require a great amount of time and energy to warm.  Tankless water heaters provide instant, unlimited access to hot water. In fact, when installed at each hot water faucet, tankless water heaters can be up to 40% more energy efficient than the conventional water heaters and run at 99% efficiency (while brand new conventional heaters are at 80%).

Tankless water heaters also called instantaneous, continuous flow, inline, flash, on-demand or instant-on water heaters have been gaining popularity in recent years.  Tankless water heaters do not retain any significant water because they instantly heat water as it flows through the unit.  Smaller tankless heaters are usually installed at each point-of-use, while one larger model may provide all the hot water for an entire house.  These heaters can be up to 40% more energy efficient than conventional water heaters.

Point-of-use tankless water heaters are installed where the water is being used, so the water is almost instantly hot (ultimately saving water since it is wasted after turning on a faucet while waiting for it to heat.  This is due to the fact that the cold water in the pipes between the faucet and the water heater needs to be flushed out first).  Additionally, no hot water is left in the pipes after the water is shut off.  This ultimately saves more water and energy than centrally installed tankless water heaters.

Historically, point-of-use water heaters were electric, typically more expensive and less efficient than gas.  A gas tankless water heater can cut approximately 30% of a homeowner’s energy usage.

Advantages of tankless water heaters:

  • Since water is heated only when needed, there is no hot water storage. With a tank, water is continuously kept hot even if it never gets used.
  • Although flow rate determines the amount of hot water generated at one time, an unlimited supply of hot water is available.
  • There is no stored water, so there is no risk of water damage from a leaking tank.
  • Most tankless water heaters can be mounted on a wall.

Disadvantages of tankless water heaters:

  • Installing a tankless system comes at an increased cost ($800 to $1,150 vs. $300 to $500 for conventional heaters), especially when installed in retro-fits.
  • Practical tankless water heaters are limited to gas and electricity.  This disqualifies renewable energy sources such as solar because of the storage tank requirement.
  • Tankless electric heaters, when installed in a large numbers of homes can create demand management problems for electrical utilities.  Because hot water use tends to peak at certain times of the day, they can cause short spikes in electricity demand.
  •     There is a short delay between the time the water begins to flow and when the heater activates the heating elements/gas burner.  Turning a hot water faucet on and off repeatedly can result in periods of hot water, then cold.
  • In a tankless water heater, the faster the flow, the less time the water spends being heated.
  • Tankless water heaters only heat water on demand; when installed far away from a faucet, the wait time for hot water increases.



Entry filed under: eco-tips, products, st. petersburg college.

St. Petersburg College’s new Natural Science, Mathematics and College of Education building is certified LEED® Gold 100% Organic, USDA Certified Organic, All Natural… What do they all mean?

2 Comments Add your own

  • 1. pb  |  July 26, 2009 at 8:02 pm

    Note that tankless water heaters may be a good alternative for businesses as well as homes.

    Pubs, Restaurants, Hotels, Motels, and more, all use TWH’s for the very large cost savings, being able to expense or depreciate the up-front costs.

    So if you have an in-home business, or you just want to make points with your boss by cutting expenses, keep that in mind.

  • 2. דוד שמש  |  June 10, 2012 at 3:39 am

    Very good blog post. I definitely love this site. Keep it up!


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Early in 2008, St. Petersburg College recognized its responsibility to model to our students, employees and community ways to minimize global warming emissions and provide the knowledge to our graduates to help achieve a more environmentally friendly future. Because of this, the College made sustainability (defined as meeting the needs of the present without compromising the ability of future generations to meet their own needs) a top priority. As a result, the Office for Sustainability was established.

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Working alongside internal and external partners, the Office for Sustainability focuses on the following areas of environmental stewardship: educational programs and corporate training, energy and natural resource conservation, green buildings and facilities, carbon emissions, recycling and student activities.

learn more:

To learn more about The Office for Sustainability at St. Petersburg College, contact Jason Green, Sustainability Coordinator at

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