A.O. Smith VB/VW- 750 manual

1 W ARNING: If the information in this manual is not followed exactly , a re or explosion may result causing property damage, personal injury or loss of life. — Do not store or use gasoline or other ammable vapors and liquids in the vicinity of this or any other appliance. — WHA T TO DO IF YOU SMELL GAS: • Do not try to light any applia[...]

2 SAFE INST ALLA TION, USE AND SER VICE 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 messages an[...]

3 GENERAL SAFETY[...]

4 Minimum clearances to combustibles: •4”(102mm)rear •0”(0mm)top&sides •6”(152mm)vent T ABLE 1. - GAS AND ELECTRICAL CHARACTERISTICS Manifold Pressure Maximum Supply Pressure Minimum Supply Pressure Model T ype of Gas Inches W .C. kPa Inches W .C. kPa Inches W .C. kPa VB/VW-500, 750, 1000 NA TURAL -2[...]

5 CAP ACITY AND FLOW DA T A T ABLE 3. RECOVERY CAP ACITIES. T ABLE 4. PUMPING PERFORMANCE GUIDE. VB MODELS - FLOW, HEAD LOSS AND TEMPERA TURE RISE 20F° (1 1°C) t 30F° (17°C) t 40F° (22°C) t Maximum Flow Rate Minimum Flow Rate MODEL GPM LPH P FT P m GPM LPH P FT P m GPM LPH P FT P m GPM LPH P FT P m T °F T ° C GPM LPH P FT P m T °F T °C VB[...]

6 This design complies with the current edition of the ANSI Z21.13 low-pressure boiler standard. 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 and other performance criteria. Detailed installation diagrams are found in this manual. These di[...]

7 GROUNDING INSTRUCTIONS This boiler must be grounded in accordance with the National Electrical Code and/or local codes. Boiler is polarity sensitive; correct wiring is imperative for proper operation. This boiler must be connected to a grounded metal, permanent wiring system, or an equipment grounding conductor must be run with the circuit conduc[...]

8 THE CONTROL SYSTEM The control system consists of four basic components: 1) Modulation Control Board (MCB); 2) Power Distribution Board (PDB); 3) V ariable Frequency Drive (VFD), see Figure 2; User Interface Module, see Figure 20. The Modulation Control Board and the Power Distribution Board are [...]

9 W A TER TEMPERA TURE LIMIT CONTROLS The “V(B/W)” modelsincorporate anoutlet water probe consisting of two limit controls: 1. A Manual Reset High limit control that can be set as high as either  210°F(99°C)or235°F(1 13°C),dependingontheapplication. 2.  A  xed manual high?[...]

10 The Discharge Pipe: • Shall not be smaller in size than the outlet pipe size of the valve, or have any reducing couplings or other restrictions. • Shall not be plugged or blocked. • Shall not be exposed to freezing temperatures. • Shall be of material listed for hot water distribution. • Shall be installed so as to allow[...]

11 FIGURE 8. CHEMICAL V APOR CORROSION Boiler corrosion and component failure can be caused by the heating and breakdown of airborne chemical vapors. Spray can propellants, cleaning sol vents, refrigerator and air conditioning refrig erants, swimming pool chemicals, calcium and sodium chloride (water softener salt), waxes, and pro[...]

12 for th e open ings th at provid e fres h air into c on ned spac es only . Do not r efer to the se illus trati ons fo r the pur po se of vent insta llati on. See Venting Inst allati on on pa ge 18 for com plete venting installation instruct ions. OUTDOOR AIR THROUGH TWO OPENINGS FIGURE 9A. The confined space shoul[...]

13 AIR FROM OTHER INDOOR SP ACES FIGURE 9E. The confined space should be provided with two permanent openings, onecommencing within 12 inches (300 mm)of the top andone commencing within 12 inches(300 mm) of thebottom of the enclosure. See Figure 9E. Each opening should communicate[...]

14 TERMINA TION CLEARANCES SIDEW ALL POWER VENT V X VENT TERMINAL AIR SUPPL Y INLE TA RE A WHERE TERMINAL IS NO T PERMITTED v v A G V FIXED CLOSED FIXED CLOSED OPERABLE OPERABLE V C B B B B F B V V A J V H M X X V V K B E D L POWER VENT (using room air for combustion) EXTERIOR CLEARANCES FOR SIDEW ALL VENT TERMINA TION Figure 9F . V ent terminal cl[...]

15 TERMINA TION CLEARANCES SIDEW ALL DIRECT VENT V X VENT TERMINAL AIR SUPPL Y INLE TA RE A WHERE TERMINAL IS NO T PERMITTED v v A G V FIXED CLOSED FIXED CLOSED OPERABLE OPERABLE V C B B B B F B V V A J V H M X X V V K B E D L DIRECT VENT (using outdoor air for combustion) EXTERIOR CLEARANCES FOR SIDEW ALL VENT TERMINA TION Figure 9G. V ent termina[...]

16 VENTING VENT SIZING, INST ALLA TION AND TERMINA TION SHALL BE IN ACCORDANCE WITH THIS INST ALLA TION MANUAL. ALL ELECTRICAL POWER AND GAS MUST BE TURNED OFF PRIOR TO ANY INST ALLA TION OF THE VENTING SYSTEM. SPECIAL INST ALLA TION CONSIDERA TIONS This boiler is a category IV appliance that can be vented using room air for intake combustion air ,[...]

17 VENTING SUPPORTS Care must be taken in the installation of the venting system that adequate support is maintained throughout the installation process. When extending more than 10 feet (3.0m) vertically , vertical support kitsare requiredonce every 10feet (3.0m)of verticalrun. V ertic[...]

18 NOTES: If the exhaust vent terminal is within 10’ (3.0m) of a wall or parapet, it must extend a minimum of 2’ (610mm) above the wall or parapet. Joints a re not joined to show vent pipe orientation. FIGURE 1 1. VERTICAL TERMINA TION. FIGURE 1 1A. HORIZONT AL THROUGH THE W ALL TERMINA TION (TWT). NOTES: Joints are not joined to show vent pipe[...]

19 DIRECT VENT INST ALLA TION REQUIREMENTS Follow the guidelines in the “HORIZONT AL INST ALLA TION REQUIREMENTS” section for the exhausting of flue  products. IMPORT ANT The labels in the Direct V ent Kit must be affixed to the boiler in locations specified by the instruction sheet provided in the kit. The following are re[...]

20 FIGURE 12. DIRECT VENT HORIZONT AL. FIGURE 12A. DIRECT VENT VERTICAL. CAUTION Direct venting into dead air spaces such as; alleys, atriums and inside corners can cause recirculation of ue gases. Recirculation of ue gases will cause sooting, premature failure of the heat exchanger and icing of the combustion air intake during severe cold we[...]

21 FIGURE 12B. DIRECT VENT , VERTICAL VENT TERMINA TION WITH HORIZONT AL INT AKE. FIGURE 12C. DIRECT VENT USING TWT WITH VERTICAL INT AKE. Option B (Figures 12B & 12C) assures no recirculation of ue gases. 70 EQUIV ALENT FEET (27.4m) OF VENTING (MAX.) AL 29-4C ® HORIZONT AL AIR INT AKE PVC PIPE 70 EQUIV ALENT FEET (27.4m) AIR INT AKE TERMIN[...]

22 SYSTEM INST ALLA TION GENERAL If the system is to be filled with water for testing or other purposes during cold weather and before actual operation, care must be taken to prevent a downdraft entering the boiler or freezing air from contacting the system. Failure to do so may cause the water in the system to freeze with resulting damage to the s[...]

23 7. SYSTEM CONTROLLER Controlling of these systems is decided mainly by the type of building system controlling desired. A single boiler installation might be controlled directly from space  temperature thermostat(s). Multiple boiler installations are more effective when the boilers are sequenced in and out of operation by some [...]

24 This is accomplished by changing two dipswitch settings on the MCB. First, dipswitch “4” must be set to the “ON” position to designate the remote probe as the controlling probe. Second, dipswitch “1” must be set to the “OFF” position to limit the maximum remo[...]

25 FIGURE 13. TYPICAL PRIMAR Y , SECONDAR Y PIPING. • INST ALLIN ACCORDANCEWITHALL LOCALCODES. • WHEN BLOW DOWN V AL VE IS REQUIRED, INST ALL  IN PLACE OF THE DRAIN V AL VE SHOWN. DANGER TEMPERA TURE SETTING SHOULD NOT EXCEED SAFE USE TEMPERA TURE A T FIXTURES. IF HIGHER PREHEA T TEMPERA [...]

26 DANGER TEMPERA TURE SETTING SHOULD NOT EXCEED SAFE USE TEMPERA TURE A T FIXTURES. IF HIGHER PREHEA T TEMPERA TURES ARE NECESSAR Y TO OBT AIN ADEQUA TE BOOSTER OUTPUT , ADD AN ANTI-SCALD V AL VE FOR HOT W A TER SUPPLIED TO FIXTURES, SEE T ABLE 8. ONE VF (MODEL VW) HOT W A TER SUPPL Y BOILER WITH VERTICAL T ANK FIGURE 14. • INST ALLI[...]

27 ONE VF (MODEL VW) HOT W A TER SUPPL Y BOILER WITH HORIZONT AL T ANK DANGER TEMPERA TURE SETTING SHOULD NOT EXCEED SAFE USE TEMPERA TURE A T FIXTURES. IF HIGHER PREHEA T TEMPERA TURES ARE NECESSARY TO OBT AIN ADEQUA TE BOOSTER OUTPUT , ADD AN ANTI-SCALD V AL VE FOR HOT W A TER SUPPLIED TO FIXTURES, SEE T ABLE 8. FIGURE 15. • INST ALL?[...]

28 WIRING Label all wires prior to disconnection when servicing controls. Wiring errors can cause improper and dangerous operation. V erify proper operation after servicing. Strict adherence to the wiring diagrams is required to prevent constant pump operation when the system controller is satised. Otherwise the warranty?[...]

29 SUGGESTED PIPE SIZING T ABLES T ABLE 7. Suggested Pipe Size For Multiple Gas Appliances (Propane Gas).  Nominal MaximumCapacityofPipeinBTU/hrandkWforGasPressuresof14in.W .C.(0.5psi)orLessand  IronPipe aPressureDropof0.5in.W .C.(basedon0.60Spe[...]

30 WIRING DIAGRAM FIGURE 17. CONNECTION DIAGRAM[...]

31 WIRING DIAGRAM[...]

32 FIGURE 18. - SCHEMA TIC DIAGRAM VB/VW-500, 750 & 1000 SCHEMA TIC DIAGRAM[...]

33 OPERA TION IMPORT ANT O n l y q u a l i  e d p e r s o n n e l s h a l l p e r f o r m t h e i n i t i a l  r i n g o f t h e b o i l e r .   At this t ime th e user sh ould not h esit ate to ask the s er vic e ag ent any quest ions re gardi ng the o per ation a nd mainte nanc e of the uni t. If you sti [...]

34 The boiler should be located in an area that is inaccessible to the general public. Never allow small children to use a hot water tap or to draw their own bath water . Never leave a child or handicapped person unat- tended in a bathtub or shower . T ABLE 8. Risk of Scalds. W ater T emperature T imetoProduce2nd&3rdDegree [...]

35 MCB - T en Position Dipswitch: Dipswitchcongurations are READ ONL Y ON POWER UP . These switches are only to be set at the factory or by authorized trained personnel! Once set the boiler will operate according to the chosen options. If a switch is changed, power must be cycled before the change will take effect. The status of all dip[...]

36 LIGHTING & OPERA TION INSTRUCTIONS FOR MODELS VB/VW 500, 750 AND 1000:[...]

37 ADJUSTMENT There must be sufcient load to operate the boiler at high re to perform the following adjustments. Start the boiler and observe proper operating parameters for the system. Required T ools: TORX ® T40 or 5mm hex wrench 3mm or 7/64in hex wrench Combustion analyzer The VF 500, 750, and 1000 b[...]

38 INPUTS TO MCB TEMPERA TURE SENSORS: T emperature 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). MRHL  (Manual Reset HIGH LIMIT): The MRHL is a hi-limit?[...]

39 NOTE: If the unit powers up with the number of stages selected by dip switches exceeding the number of FCBs, the MCB will detect this condition and go into a hard lockout. After changing the dipswitches, the power must be cycled off and back on to accept any changes.  ExampleofDipswitchconguration: VB model, 1ignition trial, not u[...]

40 UIM OPERA TING PROCEDURES FIGURE 20. UIM, USER INTERF ACE MODULE The UIM receives commands from the user and displays operational information to the user via an LCD (liquid crystal display) up to eleven LED’s,andvetouchswitches. TheLCDprovidesinformationto the user by t[...]

41 The process waits in this state until the call for heat is satised, the thermostat input is opened, or a fault occurs.  When heat is satised, the sequence continues to Post-Purge and then back to Idle. If three tries for ignition has been selected on the MCB d[...]

42 Use the following procedure to change the automatically resettable High Limit Setpoint: 1. Press the MENU key . 2. Scroll the “>” with the DOWN key next to USER SETTING SCREEN. 3. Press the SELECT key . 4. Scroll the “>” with the DOWN key until it is pointing t[...]

43 • Up and Down Keys: These keys are used to move upwards and downwards in screens to reach a desired item and to change setpoints and user settings. They have an auto increment/decrement feature for some of the configurations and values. When you first press one of the keys and value changes by 1 count, then wait 1/2 second and chan[...]

44 TROUBLESHOOTING IGNITION SYSTEM FaultMessagesandLockoutStatus(*=stagenumber:1,2,3,or4) F AUL T DISPLA YED DESCRIPTION RED LED LOCKOUT “Display Fail” Communications with UIM interrupted Continuous Auto Reset Check communication cable to UIM. T ry moving to other Internal Communications connector on MC[...]

45 TROUBLESHOOTING GAS V AL VE Problem: Non-linear CO 2 curve on adjusted boiler (deviation more than 3-6%) 1 . Possible blockage at the air inlet that prevents uniform,  constantairow . 2. The gas inlet pressure is too low at full load. Problem: Unstable CO 2 level at minimum load Theminimumload(lowfire)istoolow.?[...]

46 Any safety devices including low water cutoffs used in conjunction with this boiler should receive periodic (every six months)  inspection to assure proper operation. A low water cutoff device of the oat type should be ushed every six months.  Periodic checks, at least twice a [...]

47 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 metal vent drain and vent collector drain connec[...]

48 NOTES[...]

49 NOTES[...]

50 NOTES[...]

51 LIMITED W ARRANTY A. O. Smith Corporation, the warrantor , extends the following LIMITED W ARRANTY to the owner of this boiler: 1. If within TEN years after initial installation of the boiler , a heat exchanger or gas burner shall prove upon examination by the warrantor to be defective in mate- rial or workmanship, the warrantor , at his option [...]

52 500 T ennessee Waltz Parkway , Ashland City , TN 37015 Phone: 800-433-2545 www .hotwater .com E-Mail: parts@hotwater .com[...]