RBI Futera XLF Installation And Operation Instructions Manual

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Finned copper tube gas boilers & water heaters – Boiler Manual21TEMPERATURE RISE CONTROLWater returned to the water heater inlet mustnot be less than 140oF, 60oC or excessivecondensation of the products of combustionwill damage the water heater, voiding the warranty.The method outlined below can be employed toprevent this condition from occurring.A balancing valve should be installed on theoutlet side of the water heater for purposesof adjusting the flow rate through the heatexchanger. Thermometers are installedon both the inlet and outlet of the water heaterfor determining the temperature rise through theunit.The proper velocity through the water heatermust be maintained in accordance with Table 9,for efficient operation and long life. If thetemperature rise through the water heater islower than recommended the water velocity istoo high. Premature erosion of the heat exchangerwill occur. Conversely, if the temperature rise ishigher than recommended in Table 9, the flowrate is too low. Scaling and softening of the heatexchanger will occur.Thermostatic Mixing Valve – Water Above 140oF,60oC Water can be stored at temperatures above140oF, 60oC provided that a thermostaticallycontrolled mixing valve is used to temper thehot water to an acceptable temperature beforeit’s supplied for domestic use.The mixing valve MUST be set to prevent a scaldinjury from occurring, see the caution againstscalding.Storage of water for domestic use above 140oF,60oC will provide an increased quantity oftempered water and help prevent the growth ofwater born bacteria.When a boiler is connected to a heating coil that may be exposedto refrigerated air from an air handling device, the piping systemmust be equipped with flow-control valves or some other automaticmeans of preventing gravity circulation of the boiler water during thecooling cycle.DOMESTIC WATER SUPPLY PIPINGProper controls must be used to prevent water suppliedfor domestic use from exceeding 130oF, 54oC or a scaldinjury will occur! When higher water temperatures arerequired for appliances such as a dishwasher, a mixingvalve or some other tempering means must be installed.Households with small children may require watertemperatures less than 120oF, 49oC. Local codes mustbe complied with!General piping requirementsEnsure that the water heater is equipped with bronze headers. Pipingand components connected to the water heater must be suitable foruse with potable water. The water heater must not be connected toany heating system piping or components previously used with a non-potable water heating appliance. No toxic chemicals, such as thoseused for boiler treatment, are to be introduced into the potable waterused for space heating. If a hot water storage tank is used in the systemit must be equipped with a temperature and pressure relief valve thatcomplies with ANSI Z21.22 or CAN-4.4 and CAN-4.6.The storage tank must be located as close to the waterheater as possible to prevent excessive head loss whichwill reduce flow.Water chemistryThe required temperature rise across the water heater is based onwater having a hardness between 8 and 18 grains per gallon witha level of dissolved solids not exceeding 350 ppm. Water having ahardness less than 8 grains can cause excessive corrosion of the heatexchanger. Water that has a hardness greater than 18 grains per gallonand/or a level of dissolved solids exceeding 350 ppm will require arecalculation of the pump size and temperature rise.A cupronickel heat exchanger may also be required. The manufacturershould be consulted when these water conditions are encountered.See Table 8.The maximum allowable flow rate through a Futera XLFwater heater is 260 GPM, 16.4 L when equipped withcopper tubes. The cupronickel heat exchanger allows for315 GPM, 19.9 L/s. See Table 9.RBI water heaters are designed to run scale free. Due to the extremevariables of water conditions world wide it is necessary to considerpH values and water hardness in relationship to scaling. It is crucialto consider these two variables when making heat exchanger andpump selections. If local water conditions are extreme, follow the