RBI Gas boilers Installation And Operation Instructions Manual

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RBI Gas boilers Installation And Operation Instructions Manual Manual pdf 16 page image

Fi d b b il & h B il M lFinned copper tube gas boilers & water heaters – Boiler Manual16FFDOMESTIC WATER SUPPLY PIPINGProper controls must be used to prevent water suppliedfor domestic use from exceeding 130°F, 54°C or ascald injury will occur! When higher water temperaturesare required for appliances such as a dishwasher, amixing valve or some other tempering means must beinstalled. Households with small children may requirewater temperature less than 120°F, 49°C. Local codesmust be complied with!General Piping RequirementsEnsure that the water heater is equipped with bronzeheaders. Piping and components connected to the water heatermust be suitable for use with potable water. The water heater mustnot be connected to any heating system piping or componentspreviously used with a non-potable water heating appliance. No toxicchemicals, such as those used for boiler treatment, are to beintroduced into the potable water used for space heating. If a hotwater storage tank is used in the system it must be equipped with atemperature and pressure relief valve that complies with ANSIZ21.22 or CAN-4.4 and CAN-4.6.Th e storage tank must be located as close to the waterheater as possible to prevent excessive head loss whichwill reduce fl ow.Bleed Air From Water HeaterOpen the water heater piping bleed valves one at a time, to purgethe air trapped in the primary and secondary heat exchangers. Referto piping drawings (Figures 12 & 13) for bleed locations.Water ChemistryThe required temperature rise across the water heater is based onwater having a hardness between 8 and 18 grains per gallon with alevel 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 cupro-nickel heat exchanger may also be required. The manufacturershould be consulted when these water conditions are encountered.See Table 8.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 theguidelines in the Heat Exchanger Selection Table 9. Scale freeoperation can be achieved by using water with a hardness between8 and 18 and by maintaining the pH between 5 and 9. Followthe conditions listed under NORMAL in the table. In some areasof the country additional precautions must be observed due tounusual characteristics of the local water supply. Call the nearest RBIrepresentative for details.Expansion TankAn expansion tank or other means to control thermal expansionmust be installed in the water heating system if back flow preventiondevices are installed.Pump RequirementsThis low-mass water heater requires a continuous minimum waterflow for proper operation. The proper velocity through the waterheater must be maintained for efficient operation and long life. If thetemperature rise through the water heater is lower than recommendedthe water velocity is too high. Premature erosion of the heat exchangerwill occur. Conversely, if the temperature rise is too high, the flow rateis too low. Scaling and softening of the heat exchanger will occur. Thetemperature rise across the primary heat exchanger mustnever exceed 35°F, 19.4°C.Th e factory mounted circulatory pump is sized to workthe total boiler pressure drop and an additional 30' ofpipe and 6-90° elbows.Storage Tank Thermostatic Mixing ValveWater can be stored at temperatures above 140°F, 60°C providedthat a thermostatically controlled mixing valve is used to temperthe hot water to an acceptable temperature before it’s supplied fordomestic use.The mixing valve MUST be set to prevent a scald injury fromoccurring, see the caution against scalding.Storage of water for domestic use above 140°F, 60°C will providean increased quantity of tempered water and help prevent thegrowth of water born bacteria.