Boiler Manual - Weil-McLain

GV90+ gas-fired water boiler — Boiler ManualInstall water pipingUse two wrenches when tightening water piping atboiler, using one of the wrenches to prevent the boilerinterior piping from turning. Failure to support the boilerpiping connections to prevent them from turning couldcause damage to boiler components.The cast iron heat exchanger return temperature mustbe kept at or above 140°F during all times of operationto prevent possibility of corrosion due to condensation.This is done automatically, using the boiler's internalcirculators. DO NOT remove or tamper with these circulators.Failure to comply could result in severe personalinjury, death or substantial property damage.General piping informationAir separatorInstall an air separator in the piping as shown in thismanual. For single-zone systems, install the air separatorin the return piping as shown in Figure 14, page 14. Thisallows mounting the automatic air vent and expansion tankoff of the separator.Install relief valve1. Install relief valve ONLY as shown in Figure 12.2. Connect discharge piping to safe disposal location, followingguidelines in Figure 13, page 13.Figure 12 Install and pipe relief valveMinimum pipe size for boiler loop pipingFigure 11 Provide boiler loop piping no smaller than listedbelow (based on 20°F temperature rise)Boiler loop pipe size, MinimumGV90+3 or 4 1”GV90+5 or 6 1¼”Additional limit controlsFollowing standard industry practices, if installation is to comply withASME or Canadian requirements, an additional high temperaturelimit may be needed. Consult local requirements for other codes/standards to determine if needed. Wire as shown in Figure 67, page 56.• Install a manual reset high temperature limit between the boilerand the isolation valve.• Wire the manual reset limit in series with the boiler limit control.• Set the manual reset limit control at least 20°F above the boilerlimit control setting (maximum setting 220°F).Low water cut-off, when requiredA low water cutoff device is required when boiler is installed aboveradiation level or by certain state or local codes or insurance companies.Use low water cutoff designed for water installations. Electrode probetypeis recommended. Purchase and install in tee in supply piping aboveboiler. Wire contact as shown in Figure 67, page 56.If boiler is connected to heating coils located in air handlingunits where they can be exposed to refrigeratedair, use flow control valves or other automatic means toprevent gravity circulation during cooling cycle. Circulationof cold water through the boiler could result indamage to the heat exchanger, causing possible severepersonal injury, death or substantial property damage.Backflow preventerWhere required by codes, install a backflow preventer in the coldwater fill line, as shown in suggested piping diagrams on followingpages. Install a check valve if a backflow preventer is not installed.Legend1 Jacket plug for unused relief valve jacket opening.2 Jackets are provided with two relief valve openingsbecause each jacket size is used for two boilersizes. Cover the unused opening with the plugprovided.3 Boiler relief valve (from accessory bag)4 ¾” x 3” nipple, provided in accessory bag5 ¾” relief valve tapping in back section6 Connect minimum ¾” discharge piping to reliefvalve.See Figure 13, page 13.12Part number 550-142-054/1211