A.O. Smith DB/DW-720-1810 - Manual

6 AUTOMATIC RESET HIGH TEMPERATURE LIMIT CONTROL CAUTION LIMIT CONTROLS ARE NOT TO BE USED AS THERMOSTATS. ALL MODELS - This limit is a safety device wired in series with theignition system. Set the limit control dial to a minimum of 10°F(6°C) above the maximum designed system temperature. If theboi...

7 INSTALLATION INSTRUCTIONS REQUIRED ABILITY INSTALLATION OR SERVICE OF THIS BOILER REQUIRESABILITY EQUIVALENT TO THAT OF A LICENSED TRADESMANIN THE FIELD INVOLVED. PLUMBING, AIR SUPPLY, VENTING,GAS SUPPLY AND ELECTRICAL WORK ARE REQUIRED. WARNING THE INLET/OUTLET WATER MANIFOLD ON YOUR A. O. SMITHU...

8 If the confined space is within a building of tight construction, air forcombustion, ventilation, and draft hood dilution must be obtainedfrom outdoors. When directly communicating with the outdoors orcommunicating with the outdoors through vertical ducts, twopermanent openings, located in the afo...

9 WARNING FA I L U R E T O C O R R E C T B A C K D R A F T S M AY C A U S E A I RCONTAMINATION AND UNSAFE CONDITIONS. Vent connectors serving appliances vented by natural draft shallnot be connected into any portion of mechanical draft systemsoperating under positive pressure. 3. CONNECTING BOILER T...

10 TABLE 5 Multipliers To Be Used With Table 1 When Applying The Gravity Factor To Other Than .60 Specific Gravity Specific Specific Gravity Multiplier Gravity Multiplier .35 1.31 1.00 .78 .40 1.23 1.10 .74 .45 1.16 1.20 .71 .50 1.10 1.30 .68 .55 1.04 1.40 .66 *.60 (Nat.) 1.00 *1.50 (Prop.) .63 .65 ...

11 Applications of the gravity factor converts the figures given in table1 to capacities with another gas of different specific gravity. Suchapplication is accomplished by multiplying the capacities given intable 1 by the multipliers shown in table 5. To determine the size of each section of gas pip...

12 IF ANY OF THE ORIGINAL WIRE, AS SUPPLIED WITH THEAPPLIANCE, MUST BE REPLACED, IT MUST BE REPLACEDWITH TYPE 105°C WIRE OR ITS EQUIVALENT, EXCEPT FORTHE FLAME SENSOR AND IGNITION CABLE WHICH ARE 250°C. SERVICING WIRING AND/OR CONTROL CAUTION Label all wires prior to disconnection when servicing con...

13 The flow switch shall be mounted in the top opening of the reducingtee and provide adequate paddle length in the flow stream. Forexample in a 2" pipe installation use a 2" x 2" x 1" reducing tee. For2" or 3" pipe use the paddle segments as supplied. For other pipesizes (i....

14 Thereafter, during the heating season, lubricate the three oil cupsat least once every four months. Combination heating/coolingsystems or water heating (Cer-temp) systems should be lubricatedevery four months year-round. Use 2 or 3 teaspoonfuls in bearing oil cups, fig. 9, and 10 or 12drops in th...

15 A system bypass should be installed as shown in fig. 10 to preventboiler circulation starvation when the system zones call for reducedflow. This bypass may also be used with multiple boilers manifolded forreverse-return flow. The system bypass would be installed fromboiler outlet to suction side ...

17 BYPASS BALANCING With systems where water temperature can be expected to dropappreciably due to long standby periods, or heavy draw down, abypass pipe of at least 1" size with a balancing cock should beinstalled between the boiler inlet and outlet (see fig. 10). Whenthe system first starts, t...

18 generator type boilers establish temperature rises. The decidingfactor in choice of boiler temperature rise relates to the boiler inlettemperature. Boiler outlet, minus system temperature drop, isboiler inlet temperature. THE BOILER TEMPERATURE RISESHOULD NOT RAISE THE OUTLET TEMPERATURE UP TO TH...

19 FIGURE 14 NO. SUGGESTED ITEMS FOR INSTALLATION 1. SHORT PIPE NIPPLE AND PAIR OF BOILER LOOP TEES INPIPING BETWEEN SYSTEM SUPPLY AND RETURN - ONE SETPER EACH BOILER 2. BOILER PIPE LOOP (See Piping Sizing Data Table 3.) 3. BOILER CIRCULATING PUMP (See Piping Sizing Data Table 3.) 4. THERMOMETER 5. ...

21 DURA-MAX - PUMP MOUNT - SINGLE STAGE - SCHEMATIC DIAGRAM DURA-MAX - SINGLE STAGE FIRING - UNITED STATES MODELS WITH PUMP. 120 VOLT SYSTEM CONTROLLER

23 DURA-MAX - PUMP MOUNTED - MODULATING - SCHEMATIC DIAGRAM DURA-MAX - MODULATED FIRING - UNITED STATES MODELS WITH PUMP. 120 VOLT SYSTEM CONTROLLER

24 DURA-MAX - SINGLE STAGE FIRING - SCHEMATIC DIAGRAM DURA-MAX - SINGLE STAGE FIRING - UNITED STATES & CANADIAN MODELS WITHOUT PUMP. 120 VOLT SYSTEM CONTROLLER

27 HOT WATER SUPPLY APPLICATIONS Cer-Temp 80 Recovery Systems WATER LINE CONNECTIONS This section provides detailed installation diagrams for typicalmethods of application for the unit using a Cer-Temp 80 RecoverySystem (for one temperature water). This equipment must be protected against loss of wa...

28 ONE DURA-MAX (MODEL DW) COMMERCIAL BOILER WITH HORIZONTAL TANK CAUTION TO PREVENT CONDENSATION THE MINIMUM BOILER INLET TEMPERATURE IS 100°F (38°C) IMPORTANT SAFETY FLOW SWITCH AS SHOWN TO PROTECT THE BOILERIN CASE OF WATER SERVICE INTERRUPTION OR CIRCULATORFAILURE. CAUTION PUMP MUST BE RATED FOR...

29 TWO DURA-MAX (MODEL DW) HOT WATER SUPPLY BOILERS WITH VERTICAL TANK CAUTION TO PREVENT CONDENSATION THE MINIMUM BOILER INLET TEMPERATURE IS 100°F (38°C) SEE PAGE 31 FOR ADDITIONALPIPING INFORMATION. CAUTION P U M P M U S T B E R AT E D F O R S Y S T E M O P E R AT I N GTEMPERATURE AND PRESSURE . ...

32 START-UP AND OPERATING INSTRUCTIONS WARNING After placing boiler into operation, the ignition system safety shutoffdevice must be tested by the following test method. 1. Reset Manual High Temperature Safety Limit Control (High Limit) to the lowest setting. (See figures 3 or 4, pages 5 or 6). 2. R...

34 INTERNAL CONTAMINANTS The system must be internally cleaned and flushed after a new orreplacement unit has been installed to remove contaminants thatmay have accumulated during installation. This is doubly importantwhen a replacement unit is installed into an existing system whereStop Leak or oth...

39 CAUTION DO NOT USE A NYLON BRUSH OR OTHER STATIC CREATINGMATERIAL TO CLEAN DUST AND CARBON DEPOSITS FROMHEATING SURFACES AND VENT. SUCH DEPOSITS ARE FLAMMABLE AND MAY BE IGNITED BYSTATIC ELECTRICITY. USE A METAL BRUSH TO MINIMIZE THEDANGER OF EXPLOSION 1. Turn off the electrical power, main manua...

40 The time between cleaning will vary from two to six monthsdepending upon water conditions and usage. A change ofapproximately 5°F in the normal temperature rise through the boileris usually an indication that scale should be removed. For longlife, copper or brass is recommended for all valves, pi...

41 DURA-MAX LIMITED WARRANTY A. O. Smith Corporation, the warrantor, extends the following LIMITED WARRANTY to the owner of this hydronic boiler: 1. If within TEN years after initial installation of the boiler, the heat exchanger shall prove upon examination by the warrantor to be defective in mater...