Tankless Water Heater - AHRI

Installation ConsiderationsInstalling a gas tankless waterheater in new construction is similarto installing a storage tank waterheater. It has a cold water pipe,a hot water pipe, a gas line anda vent pipe. If a gas tankless waterheater is replacing a storagewater heater, the installer mayface challenges becauseof differences in pipe dimensionsand the materials used.For example, many gas tanklesswater heaters require stainlesssteel vent pipes that are 3 inchesto 4 inches in diameter. In addition,the required gas line size is usuallylarger for a tankless water heaterbecause of the higher BTU inputcapacities, and most require anelectrical connection. Therefore,if a homeowner is consideringreplacing a storage tank with atankless water heater, it is importantto consider the changes to the ventpipe, the gas line and electricalconnection that may be necessary.Similarly, before purchasing andinstalling an electric tankless waterheater, it is important to understandthe power requirements of thespecific model being considered toensure that the home can providesufficient power.Find More Information onTankless Water HeatersVisit the Homeowner Sectionof AHRI’s Web site atwww.ahrinet.org or findperformance certified waterheaters online in the AHRI Directoryof Certified Product Performanceat www.ahridirectory.org.U.S. Department of Energy’sOffice of Energy Efficiencyand Renewable Energy Website contains many useful energyconservation tips for consumers atwww.eere.energy.gov/your_homeGlossaryBTU – Abbreviation for British Thermal Unit. The amountof heat required to raise the temperature of a pound of waterone degree Fahrenheit.Electronic Ignition – An electrical system for igniting the gasburner. The electricity can be provided by the building’s electricsupply or a battery.Energy Factor (EF) – A measure of a water heater’s overallenergy efficiency based on the amount of hot water producedper unit of fuel consumed over a typical day. The EF is measuredbased on the U.S. Department of Energy test procedures.Energy Input Rating –The maximum amount of input energydelivered at the burner and measured in British thermal units(Btus) per hour.Flow Rate – The volume of water that is flowing througha water heater during a specific time.GPM – Gallons Per Minute. For tankless water heaters, GPMis measured using the amount of heated water that canbe delivered by the appliance at a specific temperature.Minimum Flow Rate - Tankless water heaters requirea minimum flow rate threshold to start heating water.Instantaneous Water Heater – Another term for a tanklesswater heater.Pilot – A small gas flame used to ignite gas at a main burner.Retrofit – The act of replacing one type of water heater witha different type, such as replacing a storage tank water heaterwith a tankless model.Standby Heat Loss – A measure of how much energy isconsumed to replace heat lost between heating cycles.Storage Capacity – The volume of water stored within thewater heater.Storage Tank Water Heater – A water heater that heats andstores water at a thermostatically controlled temperature.Tankless Water Heaters – A water heater that uses gas orelectricity to heat water as it flows through the appliance.Tankless Water Heater Capacity – The maximum flow ratethe water heater can produce at a given temperature risespecified as Gallons Per Minute (GPM).Temperature Rise – The temperature difference between theincoming cold water and the outgoing heated water deliveredby the water heater.

Provided by the Tankless Water Heater Group of AHRI’s Water Heater Sectionwww.hotwater.comwww.bbtna.comwww.bradfordwhite.comwww.eemaxinc.comwww.monitorproducts.comwww.noritzamerica.comwww.foreverhotwater.comwww.rheem.comwww.seisco.comwww.takagi.com2111 Wilson Blvd, Suite 500Arlington, VA 22201, USAPH 703.524.8800FX 703.528.3816www.ahrinet.org