AO Smith Boiler GB GW 400 User Guide

GAS-FIRED COMMERCIAL  
COPPER BOILERS  
FOR HYDRONIC HEATING  
AND HOT WATER SUPPLY  
GB/GW-200, -300, -400, -500, -650, -750  
USER'S INFORMATION MANUAL  
SERIES 200, 201, 202, 203  
LIGHTING INSTRUCTIONS  
These models have an automatic hot surface ignition system  
mounted on the combustion chamber panel inside the front jacket.  
This hot surface igniter ignites the main burner gas whenever the  
system control calls for heat.  
Before proceeding with operation of the unit, make sure the boiler  
and system are filled with water and all air is expelled from the boiler,  
radiator tank(s) and piping.  
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.  
WARNING  
THE MAIN MANUAL GAS SHUT-OFF VALVE MUST HAVE BEEN  
CLOSED FOR AT LEAST FIVE (5) MINUTES BEFORE  
LIGHTING. This waiting period is an important safety step.  
Its purpose is to permit gas that might have accumulated in  
the combustion chamber to clear. IF YOU DETECT GAS AT  
THE END OF THE PERIOD DO NOT PROCEED WITH  
LIGHTING. RECOGNIZE THAT GAS ODOR, EVEN IF IT SEEMS  
WEAK, MAY INDICATE PRESENCE OF ACCUMULATED GAS  
SOMEPLACE IN THE AREA WITH A RISK OF FIRE OR  
EXPLOSION.  
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 SMELL GAS  
Extinguish any open flame.  
Do not try to light any appliance.  
WARNING  
THERE IS A RISK IN USING FUEL BURNING APPLIANCES SUCH  
AS GAS WATER BOILERS IN ROOMS, GARAGES OR OTHER  
AREAS WHERE GASOLINE AND OTHER FLAMMABLE LIQUIDS  
ARE USED OR STORED, OR ENGINE-DRIVEN EQUIPMENT OR  
VEHICLES ARE STORED, OPERATED OR REPAIRED.  
FLAMMABLE VAPORS ARE HEAVY AND TRAVEL ALONG THE  
FLOOR AND MAY BE IGNITED BY THE BOILER'S MAIN BURNER  
FLAMES CAUSING FIRE OR EXPLOSION. Some local codes  
permit operation of gas appliances if installed 18 inches or more  
above the floor. This may reduce the risk if location in such an  
area cannot be avoided.  
Do not touch any electrical  
switch; do not use any  
phone in your building.  
Immediately call your gas  
supplier from a neighbor's  
phone. Follow the gas  
supplier's instructions.  
If you cannot reach your gas  
INDEX  
PAGE  
supplier, call the fire department.  
GENERAL . . . . . . . . . . . . . . . . . . . . . . .  
LIGHTING INSTRUCTIONS . . . . . . . .  
OPERATING SEQUENCE,  
IGNITION CONTROL AND DIA-SCAN II  
INSTRUCTIONS. . . . . . . . . . . . . .  
MAINTENANCE . . . . . . . . . . . . . .  
CONNECTION DIAGRAM  
1
2 - 3  
Installation and service must be  
performed by a qualified installer,  
service agency or the gas  
supplier.  
4 - 8  
8
9
WARNING  
WARRANTY. . . . . . . . . . . . . . . . . . . . . .  
10  
Should overheating occur or the gas supply fail to shut off, do  
not turn off or disconnect the electrical supply to the pump.  
Instead, shut off the gas supply at a location external to the  
appliance.  
WARNING  
A DIVISION OF A.O. SMITH CORPORATION  
EL PASO, TX MC BEE, SC RENTON, WA  
STRATFORD, ONTARIO  
Do not use this boiler if any part has been under water.  
Immediately call a qualified service technician to inspect the  
boiler and to replace any part of the control system and any  
gas control which has been under water.  
VELDHOVEN, THE NETHERLANDS  
PLEASEKEEPTHESEINSTRUCTIONSADJACENTTOBOILERAND  
NOTIFYOWNERTOKEEPFORFUTUREREFERENCE.  
PART NO. 210890-000 REV. 1  
PRINTED IN U.S.A. 2527 300  
SUPERSEDES PART NO. 210311-000  
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THE UNIT SHOULD NOT BE INSTALLED DIRECTLY ON A BE PLACED ON OR ADJACENT TO THE BOILER. OPEN  
CARPETED FLOOR. A FIRE HAZARD MAY RESULT. Instead, CONTAINERS OF FLAMMABLE MATERIAL SHOULD NOT BE  
the boiler must be installed on the A. O. Smith Combustible Floor STORED OR USED IN THE SAME ROOM WITH THE BOILER.  
Kit Base or concrete blocks extending beyond the full width and  
depth of the boiler by at least 3 (76.2mm) inches. If the boiler is Light the unit in accordance with the instructions on the lighting and  
installed in a carpeted alcove, the entire floor must be covered with operating label attached to the boiler. These instructions are  
concrete blocks, or use the A. O. Smith Combustible Floor Kit Base. repeated on the following two pages.  
FLAMMABLE ITEMS, PRESSURIZED CONTAINERS OR ANY  
OTHER POTENTIAL FIRE HAZARDOUS ARTICLES MUST NEVER  
Lighting Instructions for the G(B/W) 200 through 500 models  
2
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Lighting Instructions for the G(B/W) 650 and 750 models  
3
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ELECTRONIC HOT SURFACE  
IGNITION CONTROL BOARD  
8.  
9.  
If a flame is confirmed, the control will enter the heating  
mode where it will continue heating until the set-point tem-  
perature is reached, and the thermostat circuit opens. At  
that point, the gas valve is closed and the control enters  
the post-purge and post-circulating cycles.  
The combustion blower will run for a 25 second post purge  
cycle. When the post purge cycle is complete, the blower  
is de-energized and will coast to a stop. The circulating  
pump will continue with the post-circulate cycle for the  
selected amount of time, factory default is 45 seconds.  
See circulating pump adjustment procedure on page 5  
and 6 of this manual.  
The control now enters the idle state while continuing to  
monitor temperature and the state of other system de-  
vices. If the outlet temperature drops below the set-point  
value minus the switching differential, and the thermostat  
circuit or tank probe circuit closes, the control will auto-  
matically return to step 2 and repeat the entire operating  
cycle. During this idle state, if the control detects an im-  
proper operating state for external devices such as the  
ECO switch, air pressure switch, gas pressure switch,  
etc., the appropriate LED(s) on the Display Board will illu-  
minate indicating the nature of the fault.  
ALL MODELS - The WHC1502 ignition control board is a fully  
integrated, state of the art electronic control system. The ignition  
control board includes a microprocessor, which governs all  
temperature and ignition control functions for the appliance. Inherent  
in the design are the normal operating sequences and safety features  
associated with a gas ignition control system. The ignition control  
continuously performs various diagnostic tests to verify proper  
appliance and control operation. Should an unsafe condition occur,  
the control will shut down the burner and illuminate the appropriate  
diagnostic indicators on the Display Board, indicating a need for  
service. All operating programs are stored in permanent memory  
on the ignition control and a second programmable memory is used  
for retaining user-specific operating parameters in the event main  
power is ever interrupted.  
10.  
Line Polarity Indicator  
A green LED is mounted on the ignition control to indicate line volt-  
age polarity is properly connected. When 120 VAC input power is  
properly connected to the Ignition Control Board, the green LED will  
illuminate. If an error is made when connecting 120 VAC input  
power, this LED will not light. Improperly connecting the input power  
may result in a false flame sensor failure.  
DIA-SCAN II DISPLAY BOARD OPERATING PROCEDURES  
Fuse Protection  
The Display Board provides a user-friendly interface to the  
WHC1502 Ignition Control Board. With the Display Board, the  
user can control appliance functions and view the overall oper-  
ating status of the appliance. If an error condition occurs, the  
Display Board will scroll a message across the LED display,  
indicating the error code. Under normal operating conditions,  
the four digit LED display on the Display Board will continuously  
illustrate the water temperature sensed at temperature probe  
#1 (Outlet). The push buttons on the Display Board allow the  
user to program and view the desired water temperature set  
point. The Display Board is connected to the Ignition Control  
Board through a 6 conductor cable assembly with modular plug  
terminations. In addition, an 8 conductor modular jack on the  
Display Board allows for connecting a remote display board.  
The 24 VAC circuitry is protected with a 3 amp auto fuse. If the fuse  
opens, a red LED located near the fuse will light. If the red LED is  
illuminated, replace the fuse (recommended replacement part is  
Little fuse p/n 257003 automotive fuse). Repeated failure of the  
fuse is an indication of possible damage to the ignition con-  
trol board.  
NOTE: One extra fuse is supplied with the boiler.  
Typical Control/Appliance Operating Sequence  
1.  
When power is applied to the WHC1502 ignition control,  
the Display board will initially run through a self-diagnostic  
routine, and then go into its operating mode, displaying  
the temperature sensed at temperature probe #1 (Out-  
let).  
When power is applied to the WHC1502 System, the Display Board  
will initially run through a self-diagnostic test, and then display the  
Outlet temperature. To display a specific setting or temperature,  
press the SELECT push-button until the appropriate LED is illumi-  
nated (see figure 1). After 5 seconds, the Display Board will auto-  
matically revert to displaying the Outlet temperature. Pressing the  
ENTER/RESET push-button will hold the display in the indicated  
mode until the SELECT push-button is pressed.  
2.  
If the ignition control board determines the actual outlet  
water temperature at the temperature sensing probe  
(probe #1) is below the programmed temperature set-point  
less the switching differential, and the thermostat circuit  
or tank probe circuit closes, call for heat is activated.  
The ignition control board then performs selected system  
diagnostic checks. This includes confirming the proper  
state of the ECO/High Limit device, flow switch, and pres-  
sure switches.  
3.  
4.  
With the Display Board, the user can make adjustments to many of  
the appliance’s control features. This includes the following:  
If all checks are successfully passed, the circulating pump  
circuit is energized, then the combustion blower is ener-  
gized for the 20 second pre-purge cycle.  
Options/Features Setting Procedures  
5.  
6.  
When the pre-purge cycle is complete, the ignitor is ener-  
gized. The pump and blower should continue to run.  
The ignition control board will verify ignitor current. After  
the verification, the gas valve will open, allowing gas to  
enter the burner.  
After an additional 1 second, the ignition control board will  
monitor the flame sense probe to confirm a flame is  
present. If a flame is not verified within 4 seconds, the gas  
valve is immediately closed, and the ignition control board  
will return to step 2, unless jumper J30 is in place (ON),  
see figure 2.  
Set Appliance Temperature Set-point Value  
Set Appliance Switching Differential Value  
Select Appliance Post-Circulate Time  
7.  
Set Appliance Circulating Pump to Continuous ON Mode  
Check Appliance Cycle Count  
Control the water temperature in a storage tank  
4
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NOTE: The boiler must complete a full cycle in order for the  
new setting to take effect. If the unit is turned off  
prior to a complete cycle the setting will be lost and  
the previous setting will remain in effect.  
If the ADJUST push-button is held down long enough, the set-point  
will reach 110°F, the minimum value (or 240°F, the maximum value)  
and stop. At this point, if the desired set-point is not obtained, re-  
lease the ADJUST push-button and depress it again. The set-point  
value will now restart at 110°F (240°F) and once again increase  
(decrease) in value for as long as the ADJUST push-button is  
pressed.  
Switching Differential Adjustment Procedure  
Figure 1. Dia-Scan II Display Board.  
To facilitate proper operation and maximize appliance performance,  
the control has a programmable operating switching differential or  
"hysteresis" about the set point. This means a call for heat will  
become active when the water temperature measured at the outlet  
temperature sensing probe (Probe #1) drops to the set-point value  
minus the switching differential value. The burner will remain on  
until the water temperature measured at probe #1 reaches the set-  
point value. The switching differential value is fully programmable  
from 5°F to 50°F using the push-button(s) located on the Display  
Board. The default is set at 20°F.  
Green Status Lights  
LED 1: Call for Heat  
LED 2: Flow Switch  
LED 3: Pressure Switch  
LED 4: Ignitor Current  
LED 5: Gas Valve  
LED 6: Flame Sense  
Red Fault Lights  
LED 7: Ignition Fail  
LED 8: Circulate Failure  
LED 9: Blower Failure  
LED 10: Blocked Inlet  
To change or view the current programmed switching differential:  
LED 11: Blocked Flue  
1. Press the SELECT push-button on the display board until  
the Set-Pt differential LED (LED 16, see figure 1) is illumi-  
nated.  
Water Temperature Set Lights  
LED 12: Inlet Water Temperature *  
LED 13: Outlet Water Temperature  
LED 14: Inlet/Outlet Differential Temperature  
LED 15: Set-Point Temperature  
LED 16: Outlet/Set-Point Differential Temperature  
* Defaults to tank probe temperature when tank probe is used.  
2. The LED display will show the current switching differential.  
3. Press and hold the ADJUST push-button. The displayed value  
will either increase or decrease. To alternate between increas-  
ing or decreasing the switching differential, release then press  
and hold the ADJUST push-button.  
Temperature Set-point Adjustment Procedure  
The control board has a standard programmable temperature set-  
point range of 110°F to 240°F. The user can easily change the  
temperature set-point at any time by using the following procedure.  
In all cases, the boiler must be energized. The factory default set-  
ting is 180°F.  
4. When the desired switching differential is reached, release  
the ADJUST push-button.  
5. Press the ENTER/RESET push-button once, this enters the  
selected switching differential value into controller memory.  
To change or view the current programmed temperature set-point  
value:  
6. The appliance will now control temperature utilizing the de-  
sired switching differential value.  
1. Press the SELECT push-button on the display board until both  
the Set-Pt LED (LED 15, see figure 1) and Outlet Water Tem-  
perature LED (LED 13, see figure 1) are illuminated.  
If the ADJUST push-button is held down long enough, the switching  
differential setting will reach 5, the minimum value (or 50, the maxi-  
mum value) and stop. At this point, if the desired switching differen-  
tial is not obtained, release the ADJUST push-button and depress it  
again. The switching differential value will now restart at 5 (50) and  
once again increase (decrease) in value for as long as the ADJUST  
push-button is pressed.  
2. The LED display will show the current set-point temperature.  
3. Press and hold the ADJUST push-button. The displayed tem-  
perature will either increase or decrease. To alternate between  
increasing or decreasing the temperature, release then press  
and hold the ADJUST push-button.  
Circulating Pump Adjustment Procedure  
4. When the desired set-point temperature is reached, release  
the ADJUST push-button.  
The Controller is factory set with a 45 second post circulate func-  
tion. Using the Display Board, the user has the capability to choose  
between a 45, 90, or 180 second post circulate time period, or turn  
the pump on continuously. This provides flexibility in selecting the  
post circulate time to meet specific application requirements, and  
improves the efficiency of the circulating pump operation.  
5. Press the ENTER/RESET push-button once, this enters the  
selected set-point temperature into controller memory.  
6. The appliance will now control the temperature to the desired  
set-point value.  
5
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To change or view the current programmed post-circulating time:  
3. The display will illustrate Circ. Press the SELECT push-but-  
ton until the display illustrates Count. Enter this mode by press-  
ing the ENTER/RESET push-button.  
4. The display will now illustrate the current number of cycles the  
appliance has cycled through.  
1. Press the SELECT push-button on the display board until the  
LED display reads OPt (Options).  
2. To enter into the options mode, press the ENTER/RESET push-  
button.  
3. The display will illustrate Circ. Enter this mode by pressing the  
ENTER/RESET push-button.  
5. The display will automatically resort to illustrating the outlet tem-  
perature.  
4. The display will now illustrate the current post circulate time.  
Press the ADJUST push-button to select the desired post cir-  
culate time (45, 90, 180, On).  
5. When you have selected the desired post circulate time mode,  
press the ENTER/RESET push-button once, this enters the  
selected post circulate time into controller memory.  
6. The display will automatically resort to illustrating the outlet tem-  
perature.  
TANK PROBE INSTALLATION PROCEDURE  
A tank probe is supplied with each hot water supply boiler. When  
installed on a tank, the inlet water temperature on the Dia-Scan II  
will default to the tank temperature. See figures 2 and 3 to add  
the tank jumper to the control board so that the tank probe is  
active.  
A tank probe is NOT supplied with the hydronic heating boilers  
(GB's). Therefore, a loop or operating thermostat must be provided.  
This field-supplied operating thermostat should be wired to the  
BROWN wires at the junction box. The jumper at location J33 on  
the control board must NOT be on. Refer to figures 2 and 3 for the  
location of this jumper.  
Display Current Mode  
In this mode, the Display Board will illustrate the current functional  
step in the appliance operational sequence. For example, if the  
appliance is performing Ignitor Warm-up, the display will illustrate  
IGnt. To enter into this mode, perform the following steps:  
Tank Probe Set-Point Adjustment  
1. Press the SELECT push-button on the display board until the  
LED display reads OPt (Options).  
2. To enter into the options mode, press the ENTER/RESET push-  
button.  
3. The display will illustrate Circ. Press the SELECT push-but-  
ton until the display illustrates StEP. Enter this mode by press-  
ing the ENTER/RESET push-button.  
4. The display will illustrate the current appliance operating step.  
5. The display will automatically resort to illustrating the outlet tem-  
perature. To keep the display in the Display Step Mode, press  
ENTER/RESET twice in step 3.  
When tank probe is installed in a storage water tank, and the tank  
probe is used with the WHC1502 system, the controller will monitor  
and control the temperature of the water at the tank probe location.  
Setting the tank probe set-point temperature is accomplished  
through the Display Board control panel. The standard program-  
mable temperature range for the indirect water tank is 110°F to  
190°F. The</