GV90+ gas-fired water boiler — <strong>Boiler</strong> <strong>Manual</strong>Install 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)<strong>Boiler</strong> 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 <strong>Boiler</strong> 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
GV90+ gas-fired water boiler — <strong>Boiler</strong> <strong>Manual</strong>Install water piping (continued)Figure 13 Relief valve installation guidelinesTo avoid water damage or scaldingdue to relief valve operation, asper local or state codes:Discharge line must be connectedto relief valve outlet and run to asafe place of disposal. Terminate thedischarge line in a manner that willprevent possibility of severe burnsor property damage should the valvedischarge.Discharge line must be as short aspossible and be the same size as thevalve discharge connection throughoutits entire length.Discharge line must pitch downwardfrom the valve and terminate at least6” above the floor drain where anydischarge will be clearly visible.The discharge line shall terminateplain, not threaded, with a materialserviceable for temperatures of375°F or greater.Do not pipe the discharge to anyplace where freezing could occur.No shutoff valve shall be installedbetween the relief valve and boiler,or in the discharge line. Do notplug or place any obstruction in thedischarge line.Test the operation of the valve afterfilling and pressurizing system bylifting the lever. Make sure the valvedischarges freely. If the valve fails tooperate correctly, replace it with anew relief valve.Failure to comply with the aboveguidelines could result in failure ofthe relief valve to operate, resultingin possibility of severe personal injury,death or substantial propertydamage.Expansion tankFigure 14, page 14 and Figure 15, page 14 show typical installation of theexpansion tank. Always locate the air separator and expansion tank asshown in the suggested piping drawings, beginning with Figure 17, page 16.Ensure that the expansion tank size will handle boiler and system watervolume and temperature. See tank manufacturer’s instructions and ratingsfor details. Additional tanks may be added to the system if needed tohandle the expansion. These tanks may be installed by connecting to teesin the system piping.Undersized expansion tanks cause system water to be lostfrom the relief valve and makeup water to be added throughthe fill valve. Eventual section failure can result. Always locatethe cold water fill connection at the expansion tank. Neverlocate this elsewhere in the system.Diaphragm- or bladder-type tank:Refer to Figure 14, page 14 for suggested piping when using a diaphragmorbladder-type expansion tank.Diaphragm- or bladder-type expansion tank — Controlfill pressure with the tank air charge pressure. Always checkpressure and charge tank with tank removed from systemto be sure reading is accurate. <strong>Boiler</strong> relief valve is set for 30PSIG. Operating pressure of system, after temperature expansionabove cold fill pressure, should not exceed 24 PSIG toavoid weeping of relief valve.Install an automatic air vent on top of the air separator, per separatormanufacturer’s instructions.Closed-type expansion tank:Figure 15, page 14 shows suggested piping when using a closed-type expansiontank, in which the air is directly in contact with tank water.Connect piping (½” or ¾”) from the air separator top outlet to the tankfitting. Slope any horizontal piping a minimum of 1 inch per 5 feet ofhorizontal pipe.Always use a tank fitting, such as the B&G Tanktrol or Taco Taco-Trol(shown). The fitting reduces gravity flow of water in the piping to thetank, avoids air bubbling through the tank water, and provides the properfill height in the tank.Correct all leaks in the system or tank piping. Leaks allowair to escape from the system and will cause water-loggingof the tank. This will result in water loss through the boilerrelief valve due to over-pressurization.NEVER use an automatic air vent in a system equipped with aclosed-type expansion tank. The air removed from the systemwill cause water-logging of the expansion tank.Closed-type expansion tank — Follow tank manufacturer’sinstructions for filling the tank. Typical tank sizing providesfor approximately 12 PSIG when the tank is filled to thenormal level and system water is cold. Note that boiler reliefvalve is set for 30 PSIG. Operating pressure of system, aftertemperature expansion above cold fill pressure, should notexceed 24 PSIG to avoid weeping of relief valve.Part number 550-142-054/1211 13