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NORA Oilheat Technicians Manual

Figure 13-23: Internal tankless coil Chapter 13 Heating Systems Figure 13-24: External tanless coil Chapter 13—Heating Systems 13-19 gasket is then bolted to the boiler shell. This system requires that boiler water temperature be maintained high enough to heat the water as it passes through the coil. There is no storage capacity in this system, and during heavy draw it is unable to provide enough hot water due to its limited capacity. See Figure 13-23. External tankless coils are copper, cast iron or steel tanks with a coil inside. See Figure 13-24. Boiler water is piped to the tank and it is kept hot by gravity or forced flow circulation. Many new systems feature an updated version of the external tankless called a plate heat exchanger. It is made of a series of wafers or plates with internal porting. The plates alternate between boiler water and domestic water. See Figure 13-25 on following page. Tankless coil with a storage tank This system, often called an aqua-booster, is a combination of a storage tank and tankless coil. Water is heated by the coil and stored in the tank. The tank temperature is maintained by a recirculation loop that allows the water to go back to the coil by forced circulation. Forced circulation is maintained by a noncorrosive circulating pump usually made of bronze or Tankless Coil Cold Water In DHW Supply Out Boiler Tankless Coil DHW Supply Out Cold Water In Sidearm


NORA Oilheat Technicians Manual
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