Camus Hydronics DFH/W500 Installation, Operation And Service Manual

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Camus Hydronics DFH/W500 Installation, Operation And Service Manual Manual pdf 24 page image

19Return Water Temperatures Required for DynaFlame®Boilers & Water HeatersMinimum acceptable return water temperatures aredetermined by the category of the heater. This is truefor all manufacturers.A category I machine like the non-condensing version of theDynaFlame® 85% efficient model can be operated with returnwater temperatures as low as 115ºF (46oC) provided that thecontrol algorithm is correct. Proper operation requires initialstartup of the machine followed by ramp up to high fire. Thissequence minimizes initial condensation and generates stacktemperatures which dry up initial condensation in the vent.Category II machines like the near condensing versionDynaFlame® 88% efficient model (DFX) and the condensingDynaFlame® 95% efficient can be operated down to 20% firingrate from initial startup. These machines must be operated witha return water temp of at least 130ºF (55oC) to the primary heatexchanger in order to avoid condensation there. For theseappliances condensation in the vent is not an issue becausethey are installed with a special venting system designed towithstand the corrosive action of condensate.The Camus® designs are versatile and user friendly, theydeliver optimal performance by taking full advantage of existingsite conditions in order to maximize energy savings.IMPORTANTOperating this appliance at return water temperaturesbelow the recommended temperature (except initial heatup) may cause primary heat exchanger to fail and mayeventually cause hazardous conditions that may result inpersonal injury or non-warrantable damage to the unit.4.6 LOW WATER TEMPERATURE SYSTEMSAll DynaFlame® heaters can be configured for low watertemperature applications including open water reservoirheating.Recirculation loops required for these applications can be setup in the field or they can be supplied pre-piped from thefactory.In applications where the heating system requires supply watertemperatures below the recommended temperature, a bypassline must be installed upstream of the appliance pump so thatoutlet water can be re-circulated to raise the inlet temp to aminimum of the recommended temperature. Balancing valves,preferably circuit setter or globe valves are used to adjust flow.(See Figure 16)Figure 17: Typical Low-Water Temperature System(Non-Condensing)Adjustment Procedurea) Fully open bypass and outlet valves.b) With appliance running, read appliance inlettemperature after 15 minutes.c) If inlet temperature is less than the recommendedtemperature slowly close outlet valve until the inlettemperature climbs to slightly above therecommended temperature.d) If inlet temperature is greater than the recommendedtemperature but not greater than 140°F no furtheradjustment is required.e) Check inlet temperature after 5 minutes and makefinal adjustments.f) Remove handle of balancing valve to preventtempering.Note: For applications where large volumes of water areheated from ground water temperatures to processtemperatures, it will be necessary to provide a modulatingthree way valve or thermostatic valve in lieu of a fixedbypass line.4.7 INSTANTANEOUS WATER HEATER (non-condensing)An instantaneous water heater is designed to deliver hotwater without the use of a storage tank. It is suitable forapplications with variable load such as restaurants,condominiums, apartments and motels and typically usedin conjunction with tempering valves to achievetemperature control. In some applications it may beappropriate to provide a flow through tank to act as abuffer. Consult factory for recommendations. (See Figure17)