1 warning: if the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or loss of life. — do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance. — what to do if you smel...
2 setting of the test mode ................................................................13 control system ..............................................................................13 inputs to mcb ................................................................................14 operating seq...
3 the proper installation, use and servicing of this boiler is extremely important to your safety and the safety of others. Many safety-related messages and instructions have been provided in this manual and on your boiler to warn you and others of a potential injury hazard. Read and obey all safety...
4 general safety breathing hazard - carbon monoxide gas special consideration must be taken with installation above 4500 feet. Please contact an a. O. Smith qualified service agent to obtain the proper setup and instructions before lighting. Failure to implement the proper setup will result in impro...
5 this design complies with the current edition of the ansi z21.13 - csa 4.9 standard for gas fired low pressure steam and hot water boilers. Compliance under this standard implies that when the boiler underwent test, the gas manifold and control assembly pro vided on the boiler met safe lighting an...
6 for all side wall terminated, horizontally vented power vent, direct vent, and power direct vent gas fueled water heaters installed in every dwelling, building or structure used in whole or in part for residential purposes, including those owned or operated by thecommonwealthandwherethesidewallexh...
7 figure 1 - schematic diagram hot 120vac on/off switch 20 amp fuse (pdb – f2) pump relay contacts circulating pump (vw units only) neutral 120vac rtn 10 amp fuse (pdb – f6) k8 (mcb-ii) pump relay coil r igniter k11 (mcb-ii) gas valve k5 (mcb-ii) k4 (mcb-ii) k6 (mcb-ii) 15 amp fuse (pdb – f7) 3 amp ...
8 figure 2. Connection diagram mcb-ii detail a part of j-box vb/vw 1500/2000 wiring diagram on/off main power switch input 120vac power f2-20a 1 2 3 4 5 6 j1 f3-3a 1 2 3 6 7 j2 1 2 3 4 5 6 15 j3 f7-15a f6-10a power distribution board (pdb) blower fuse pump fuse xformer fuse mcb-ii fuse tb1 transform...
9 mcb-ii detail a part of j-box vb/vw 1500/2000 wiring diagram on/off main power switch input 120vac power f2-20a 1 2 3 4 5 6 j1 f3-3a 1 2 3 6 7 j2 1 2 3 4 5 6 15 j3 f7-15a f6-10a power distribution board (pdb) blower fuse pump fuse xformer fuse mcb-ii fuse tb1 transformer 120/24 vac modulating cont...
10 operation important only a certified start-up agent should perform the initial firing of the boiler. At this time the user should not hesitate to ask the start-up technician any questions regarding the operation and maintenance of the unit. If you still have questions, please contact the factory ...
11 hot water temperatures required for automatic dishwasher and laundry use can cause scald burns resulting in serious personal injury and/or death. The temperature at which injury occurs varies with the person’s age and time of exposure. The slower response time of children, aged or disabled person...
12 lighting and operating instructions.
13 adjustment theremustbesufficientloadtooperatetheboilerathighfireto perform the following adjustments. Start the boiler and observe proper operating parameters for the system. Required tools: torx ® t40 or 5mm hex wrench 3mm or 7/64in hex wrench combustion analyzer these boilers are equipped with ...
14 inputs to mcb temperature sensors: temperature probes (mcb - outlet and either inlet or tank are required): the mcb accepts analog temperature inputs from up to three sensors (inlet, outlet, and tank). Manual reset high limit(mcb-required):themrhlormanual reset high limit is a hi-limit switch loc...
15 operating sequence 1. Theemcmodulationcontrollerhasfourmodesofoperation: initialization, standby, running/modulation, and service. The internal mcb micros control these modes through a sequence of steps (or states) which are further described in the “uim operating procedures” section. 2. When pow...
16 • temperature screen: displays the sensed temperatures of the outlet, inlet, and tank probes. Also displayed is the calculated delta t (outlet minus inlet) for the system. Shorted (“short”) and disconnected (“----”) probes are also displayed. • system status screen: this screen is used to view st...
17 this state until the mcb sends a command to clear the error, and the system returns to the idle state. • coldpurgestate cold purge occurs when the mcb micro commands the blower to go on before lighting to clear the unit of residual gases. This state normally lasts approximately 32 seconds but on ...
18 the software revision level of the mcb. • current error screen: displays the last error that the system has detected plus a time stamp of when the error occurred. (the time stamp is based on the elapsed hours value at the time the error occurred. It is displayed in hours and minutes. This error r...
19 troubleshooting ignition system faultmessagesandlockoutstatus(*=stagenumber:1,2,3,or4) fault displayed description red led lockout “display fail” communications with uim interrupted continuous auto reset check communication cable to uim. Try moving to other internal communications connector on mc...
20 troubleshooting gas valve problem: non-linear co 2 curve on adjusted boiler (deviation more than 3-6%) 1. Possible blockage at the air inlet that prevents uniform, constantairflow. 2. The gas inlet pressure is too low at full load. Problem: unstable co 2 level at minimum load the minimum load (lo...
21 any safety devices including low water cutoffs used in conjunction with this boiler should receive periodic (every six months) inspection toassureproperoperation.Alowwatercutoffdeviceofthefloat typeshouldbeflushedeverysixmonths.Periodicchecks,atleast twice a year, should be made for water leaks. ...
22 lines with air or water and clear or replace the blocked portions of the line as necessary. Note that areas of the drain line which include a sag or low spot in the line will also form a condensate trap which can be removed by levelling the tube and does not indicate a blocked system. Inspect the...
23 limited warranty a.O.Smithcorporation,thewarrantor,extendsthefollowinglimitedwarrantytotheownerofthisboiler: 1. If within ten years after initial installation of the boiler, a heat exchanger or gas burner should prove upon examination by the warrantor to be defective in material or workmanship, t...
24 500 tennessee waltz parkway, ashland city, tn 37015 technicalsupport:800-527-1953•parts:800-433-2545•fax:800-644-9306 www.Hotwater.Com.
