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Published on January 26th, 2009 | by Stephanie Evans


The Tankless Water Heater for Long-Term Savings

Just as a calm, warm shower can cleanse the body, a green way of doing it can soothe the soul. While residents leave the heat off in their homes when they leave for vacation, the same cannot be said for hot water in most households. It seems only logical to leave the hot water off when it is not needed.

This is the logic behind the “tankless” or “instant” water heater, which provides on-demand and instantaneous hot water at an efficient and less costly rate. And though the intangible savings of fossil fuel pollution and water waste are not immediately apparent, the fact that energy and water are such indelible aspects of a home’s eco-footprint means that the water heater is an ideal target for those aiming to conserve.
Solar Water Heater

Tankless heaters not only save several square feet of storage space—there’s also no stand-by energy losses and no sitting water.  Typical tankless water heaters can be about 35 percent more energy efficient than traditional storage tank water heaters for a home that uses about 40 gallons of hot water a day. 

Depending on the extent of their use, tankless heaters can yield energy savings of up to 50 percent if they are installed in a strategic and advantageous manner.  Since approximately 15 percent of the total energy expenditure of typical households goes to heating water, the benefits can be far-reaching.

Like most green building features, the product costs more initially and saves…over the course of the product’s lifespan….for people who want to integrate green building systems into their homes, going tankless is an effective way of striving toward that goal.

For the eco-conscious, solar water heating is the best, though the current price tag can be a bit daunting.  The next best step is "going tankless" with an electric or gas-powered heater.  It is imperative to do some homework to determine what kind of tankless system will work best with the distinguished features of the home and the lifestyle of its occupants.

The Basics of Tankless

On Demand Hot Water

Before scurrying to the store, it is advisable to know how tankless systems actually work.  When the hot water tap is turned on, cooler regular water pumps through a pipe into the water heater unit.  This on-demand design frees home owners from having to wait for a water tank to fill up with enough water.

In general, gas-powered tankless heaters produce higher flow rates of water compared to electric heaters.  The drawback is that some gas-powered heaters with pilots actually waste energy, thereby negating the good intentions of the eco-conscious resident.  You can curb this waste factor by:

  • Purchasing pilot lights that you can turn off
  • Installing models that have intermittent ignition devices, similar to spark ignitions in gas ovens

Gas-powered models rely on either propane or natural gas and require stainless steel venting accessories that can run up the purchase by an extra few hundred dollars.

For electric heaters, consult with a reputable electrician, who can recommend voltage and survey your home for circuits. Most retailers sell heaters that will accommodate voltages of 110, 120, 208, 220, 240, and 277.  For gas, the decision comes down to propane or natural gas and considering where the discharge will go.

When you are serious about contacting a contractor:

  • Check backgrounds at the local Better Business Bureau and get several estimates.
  • Contact the city or county to learn about permits and codes.
  • Be sure that the contractor is well informed about local government standards as well.

Ideally, you’ll find a contractor who shares and understands your goal of reducing your energy consumption and water usage.  The contractor can then consider the most strategic heating unit placement as they develop their plans, because the efficiencies of tankless heaters diminish the farther they’re located from the area in the home that needs hot water.

Examining Your Lifestyle

If you’re not such a whiz with mathematical calculations, a good way to polish your arithmetic skills is to formulate how a tankless water heater can reconcile your daily household routine with your green conscience.

Calculating Flow Rate Demand

A strong tankless heater can pump about 5 gallons a minute of hot water throughout the whole house.  But if your teenaged kid likes taking 15-minute showers while you run the dishwasher, this might not suffice.  Calculating your flow-rate demand is key in determining whether to install one heater for the whole house or multiple heaters for different appliances and bathrooms.  In a busy household, all of these appliances running at the same time can challenge a tankless heater’s ability to meet hot water demand.

In addition, the climate conditions where you live can affect the performance of your heating unit.  There is a notable difference between operating a tankless heater in Michigan compared to operating one in Arizona in the dead of February.  Naturally, water in the Southeast desert is warmer and is thus less taxing on your heater.

To run the numbers in a calculation checklist:

  • First, list the number of hot water devices in your house that may be used at the same time.
  • Add up their flow rates based on gallons per minute.  
    • Kitchen sinks use about 1 gallon/minute. 
    • Showers are between 2.5-3 gallons/minute.
    • Larger appliances like dishwashers require 3 gallons/minute.

If your incoming water temperature for the shower is 60 degrees and you want to enjoy a 125 degree shower at a water flow rate of 3 gallons/minute, you will need a heater capable of reaching at least 65 degrees at 3 gallons/minute.  If you want your heater to provide for more than just the shower—such as the kitchen sink or the dishwasher—then they need to be factored into the equation when investigating the heating unit’s capabilities.

Powerful gas-powered tankless heaters can warm water 70 degrees at five gallons/minute, while electric heaters can achieve two gallons/minute.Faster flow rates or cooler inlet temperatures can sometimes reduce water temperature at the most distant faucet.  In a busy household, some residents might want to run a bath tub at a lower flow rate for a warmer bath.

Tankless is an Investment

Like most green building features, the product costs more initially and saves money and energy consumption over the course of the product’s lifespan.  Tankless water heaters vary in price and usually cost several hundred dollars more than the typical tank heater.  In addition, installation can notch the price up into the four figures.  Consulting a contractor and acquiring a permit through the city or county are both time-consuming and cumbersome.

No Need to Recycle Tankless Water Heaters!

But for people who want to integrate green building systems into their homes, going tankless is an effective way of striving toward that goal.  Amid rising energy costs and water bills in some regions of the country, current savings can hover around $100 a year.

Tankless water heaters last for about 20 years, compared to the 10 to 15 year lifespan of the tank.  And tankless heaters feature easily replaceable parts that can extend its lifespan years beyond that.  Tax credits are available for making the improvement, which can save you hundreds of dollars.  Check your state’s Web site for more information.  At the federal level, The Energy Policy Act of 2005 provides tax credits through 2007 for homeowners who make such improvements.

The leap from the tank takes time, money, and patience.  But once the leap is made, those warm showers might become a little warmer.


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