RBI 8900 Series Installation & Operation Manual

Also see for 8800 Series: Installation & operation manual Installation and operation manual Installation and operation instructions

Contents

SERIES 8800 & 8900 INSTALLATION AND OPERATING INSTRUCTIONSPage 12Low Water CutoffIf a boiler is installed above any radiation elements itmust be fi tted with a low water cutoff device.Refer to the wiring diagram supplied with the boiler/water heater for proper wiring connections.Expansion TankAn expansion tank or other means to control thermalexpansion must be installed in the heating system. Anexpansion tank must be installed close to the boiler onthe suction side of the pump.Primary/Secondary PipingBoilers connected to heating systems using zonevalves, zone pumps, or systems that have excessiveflow rates or return water temperatures less than 110°F,43°C must be isolated from these systems to protect theboiler.Variable Water FlowsFigure 7 shows a typical primary/secondary pipingsystem. A dedicated pump is used to maintain aconstant water fl ow through the boiler. This secondarypump is sized to overcome the head loss of the boilerand secondary piping system while supplying the fl owrate required to maintain the desired temperature riseacross the boiler. The primary pump is sized to providethe required fl ow to the heating system. The secondarypiping connections to the primary system piping mustnot be more than 12 in, 305 mm apart to ensure zeropressure drop in the primary system, see Figure 7.Low Return Water TemperaturesTo prevent the problems associated with condensationof the products of combustion due to low return watertemperatures a primary/secondary piping system witha bypass and bypass valve must be installed, seeFigure 8. The bypass and bypass valve must be sizedthe same as the secondary piping. A balancing valvemust also be installed in the supply side of thesecondary piping downstream of the bypass. Thebalancing valve should be adjusted to divert some ofthe heated discharge water into the return water untilthe required inlet water temperature is achieved. Theprimary and secondary pumps should be sized toprovide the required flow through each system. Thesecondary piping connections to the primary systempiping must not be more than 12 in, 305 mm apart toensure zero pressure drop in the primary system, seeFigure 8.Multiple Boiler SystemsSystems using multiple boilers can also be installedusing a primary/secondary manifold system, Figure 9.Piping For Use With Cooling UnitsThe boiler, when used in connection with a refrigerationsystem, must be installed so the chilled medium is pipedin parallel with the boiler. Appropriate valves must beused to prevent the chilled water from entering theboiler.When a boiler is connected to a heating coil that maybe exposed to refrigerated air from an air handlingdevice, the piping system must be equipped with flow-control valves or some other automatic means ofpreventing gravity circulation of the boiler water duringthe cooling cycle.