Atlanta Tankless Water Heaters

How Tankless Hot Water Heaters Work

Tankless water heaters, often referred to as instant or instantaneous water heaters, do not instantly heat water.  Heating water takes time whether it’s a big tank full, or a long piece of tubing coiled up over a natural gas burner.

Tankless water heaters have pros and cons, just like everything else.  They can supply an endless supply of hot water, and can save you energy because they do not have standby losses like storage type water heaters.

However, they are limited in the amount of hot water that can be produced at one time and they are more expensive to purchase and install than a conventional storage type water heater.

They also make it take longer for you to get your hot water, since they don’t start heating the water until you turn on the faucet. Typically they add 10 to 20 seconds to the time it takes to get hot water to the fixture. 

There is a minimum flow rate required to turn on the heater, typically between .5 gallons per minute and .75 gallons per minute. This means letting the faucet run with just a trickle of hot or warm water will not work. You will need at least 1/2 gallon per minute of flow or more to turn on the unit.

Some dishwashers and washing machines do not have enough flow to turn on the heater.

Energy Savings

Tankless hot water heaters save energy and thus money.  Water heating accounts for up to 20% or more of an average household’s annual energy expenditures. The yearly operating costs for conventional gas or electric storage tank water heaters average $200 or $450, respectively.  This places the monthly savings at about $3.00 to $9.00 a month. 

Storage tank-type water heaters raise and maintain the water temperature to the temperature setting on the tank (usually between 120° -140° F (49° -60° C). Even if no hot water is drawn from the tank (and cold water enters the tank), the heater will operate periodically to maintain the water temperature. 
This is due to “standby losses”: the heat conducted and radiated from the walls of the tank—and in gas-fired water heaters—through the flue pipe. These standby losses represent 10% to 20% of a household’s annual water heating costs. 

Tankless units are common in Japan and Europe. They began appearing in the United States about 30 years ago. Unlike “conventional” storage tank water heaters, tankless water heaters heat water only as it is used, or on demand. A tankless hot water heater has a heating device that is activated by the flow of water when a hot water valve is opened. Once activated, the heater delivers a constant supply of hot water. The output, however, limits the rate of the heated water flow.

Point of use

In the past tankless water heaters were usually used as “point of use” heaters.  Point of use water heaters operate more efficiently than whole house water heaters since there is only a short distance between the heater and the fixture.  This eliminates the piping losses and reduces the hot water used each time a use occurs.  With a long pipe, when you finish using hot water you have also “used” all the hot water left to cool in the pipe.  You paid for the energy to heat that water.

Point of use installations use smaller heaters since they don’t have to supply more than one fixture at a time.  The smaller installations are much less expensive than whole house water heaters.