Qualified Remodeler Magazine

JUL 2018

Qualified Remodeler helps independent remodeling firms to survive, become more professional and more profitable by providing must-have business information, namely best business practices, new product information and timely design ideas.

Issue link: https://qualifiedremodeler.epubxp.com/i/1004762

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Page 52 of 67

heater and the flame extinguishes. e unit will stay off until the next time a need for hot water occurs, such as turning on a shower, washing machine, dishwasher or faucet. Combustion produces the energy required to heat cold water, but the process also creates exhaust gases that a non-condensing tankless water heater will vent immediately. e unit loses about 20 percent of the heat generated from combustion as a result, and the material used for venting must be able to withstand the release of extremely hot gases, which can reach temperatures up to 300 F. A condensing tankless water heater, how- ever, employs a secondary heat exchanger to extract the warmth from these gases and preheat the water. is extra step can induce an efficiency rating of more than 90 percent, and the cooler exhaust gases (around 100 F) permit a much less expensive material than the special Category III stainless steel necessary for venting a noncondensing unit. As the gases cool inside a condensing unit, though, they form condensation that can cor- rode heat exchangers and other critical parts. Many manufacturers now offer WiFi com- patibility for their tankless products as well, which enables homeowners to monitor and tweak usage from a mobile device. e wire- less adaptor, when used in conjunction with an app, allows customers to create and man- age their own schedules and often connects to a smart home network—such as Nest or Wink—to provide even greater convenience. HOW THEY OPERATE As soon as a hot water tap opens, the water flow sensor inside a tankless unit alerts the computer board, which turns on a fan to clear the vent and ensure fresh air for combustion. A flame ignites and warms the burner. Cold water flows into the unit from an inlet pipe, passing through the heat exchanger and ab- sorbing warmth from the burner before exit- ing at the desired temperature. e computer board automatically adjusts the flame output if another tap opens and the hot water flow rate changes, so that the temperature remains steady. As the hot water taps close, cold water stops flowing into the ese elements must be constructed with ma- terials capable of resisting corrosion, such as a stainless steel alloy. e condensation that has collected within the unit needs to be neu- tralized through special filtration or dilution before it can be drained outside. "Tankless water heaters have come a long way since first hitting the market," says Andrew Tran, marketing manager for Noritz. "Improved heat exchangers have allowed for a more efficient heat transfer. A major improve- ment in our [tankless] heaters' design [has] allowed for the industry's strongest stainless steel to be used in the heat exchanger, which improves the heaters' longevity." WHEN THEY IMPROVE Even though tankless water heaters provide reliable performance and savings, manufac- turers continually look for ways to heat the same quantity of water with a smaller amount of energy. For example, an integrated pump can recirculate cooled water languishing in a hot water pipe back to the unit through a dedicated return line, so that users in a house receive hot water quicker. RHEEM's High Efficiency Tankless Gas Water Heater with Built-in Recirculation delivers a continuous flow of hot water without the wait, boasting a maximum of 11 gallons per minute and a Uniform Energy Factor (UEF) up to 0.94. Circle 5 on inquiry card RINNAI's M-Series Condensing Boiler (left) combines new burner technology with a stainless- steel water heat exchanger, while the Sensei Tankless Water Heater (right) offers professionals flexible and faster installation as well as superior performance. Circle 4 on inquiry card QualifiedRemodeler.com QR July 2018 53

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