AO Smith Water Heater 500 User Guide

GAS-FIRED COMMERCIAL  
COPPER BOILERS FOR HYDRONIC  
HEATING AND HOT WATER SUPPLY  
USER'S INFORMATION MANUAL  
GB/GW-300, 400, 500, 650, 750  
SERIES 400, 401, 402, 403, 404, 405,  
2-STAGE UNITS  
WARNING  
Should overheating occur or the gas supply fail to shut off, do  
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.  
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  
— Do not store or use gasoline or other  
flammable vapors and liquids in the  
vicinity of this or any other appliance.  
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.  
— WHAT TO DO IF YOU SMELL GAS:  
Do not try to light any appliance.  
• 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.  
INDEX  
PAGE  
LIGHTING INSTRUCTIONS ....................................... 2-3  
MAINTENANCE .......................................................... 3-4  
OPERATING SEQUENCE, EMC5000 ......................... 8-14  
CONNECTION DIAGRAM ............................................ 13  
EMC5000 INSTRUCTIONS ...................................... 14-18  
WARRANTY................................................................. 19  
• If you cannot reach your gas  
supplier, call the fire department.  
— Installation and service must be  
performed by a qualified installer,  
service agency or the gas supplier.  
CAUTION  
TEXT PRINTED OR OUTLINED IN RED CONTAINS  
INFORMATION RELATIVETO YOUR SAFETY. PLEASE READ  
THOROUGHLY BEFORE INSTALLING AND USING THIS  
APPLIANCE.  
ADIVISION OFA. O. SMITH CORPORATION  
MC BEE, SC., RENTON, WA.,  
STRATFORD-ONTARIO, VELDHOVEN-THE NETHERLANDS  
PLEASE KEEP THESE INSTRUCTIONS ADJACENT TO BOILER AND  
NOTIFY OWNER TO KEEP FOR FUTURE REFERENCE.  
PRINTED IN U.S.A. 0306  
PART NO. 212132-001  
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FLAMMABLE ITEMS, PRESSURIZED CONTAINERS OR ANY  
OTHER POTENTIAL FIRE HAZARDOUS ARTICLES MUST  
NEVER BE PLACED ON ORADJACENT TO THE BOILER. OPEN  
CONTAINERS OF FLAMMABLE MATERIAL SHOULD NOT BE  
STORED OR USED IN THE SAME ROOM WITH THE BOILER.  
THE UNIT SHOULD NOT BE INSTALLED DIRECTLY ON A  
CARPETED FLOOR. A FIRE HAZARD MAY RESULT. Instead,  
the boiler must be installed on the A. O. Smith Combustible  
Floor 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 installed in a carpeted alcove, the entire floor must be  
covered with concrete blocks, or use theA. O. Smith Combustible  
Floor Kit Base.  
Light the unit in accordance with the instructions on the lighting  
and operating label attached to the boiler. These instructions  
are repeated on the following two pages.  
Lighting Instructions for the G(B/W) 300 through 750 models  
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It is recommended that lower water temperatures be used to  
avoid the risk of scalding. It is further recommended, in all cases,  
that the water temperature be set for the lowest temperature  
which satisfies the user's hot water needs. This will also provide  
the most energy efficient operation of the water heater and  
minimize scale formation.  
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.  
SETTING THE WATER HEATERTEMPERATUREAT 120°F WILL  
REDUCE THE RISK OF SCALDS. Some states require settings  
at specific lower temperatures. Table 1 below shows the  
approximate time-to-burn relationship for normal adult skin.  
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.  
Table 1: Risk of Scalds  
WARNING  
THE MAIN MANUAL GAS SHUT-OFF VALVE MUST HAVE BEEN  
CLOSED FORAT 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  
GASODOR, EVENIFITSEEMSWEAK, MAYINDICATEPRESENCE  
OFACCUMULATEDGASSOMEPLACEINTHEAREAWITHARISK  
OF FIRE OR EXPLOSION.  
Temperature  
Setting  
Time to Produce 2nd & 3rd  
Degree Burns onAdult Skin  
Nearly instantaneous  
About 1/2 second  
Over 170°F  
160°F  
150°F  
About 1-1/2 seconds  
Less than 5 seconds  
About 30 seconds  
140°F  
130°F  
120°F or less  
More than 5 minutes  
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 VAPORSARE HEAVYAND TRAVELALONG THE  
FLOORAND MAY BE IGNITED BYTHE 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.  
BOILER LOCATION  
Water heater life depends upon water quality, water pressure  
and the environment in which the water heater is installed. Water  
heaters are sometimes installed in locations where leakage  
may result in property damage, even with the use of a drain pan  
piped to a drain. However, unanticipated damage can be reduced  
or prevented by a leak detector or water shutoff device used in  
conjunction with a piped drain pan. These devices are available  
from some plumbing supply wholesalers and retailers, and  
detect and react to leakage in various ways:  
TEMPERATURE REGULATION  
DANGER  
Sensors mounted in the drain pan that trigger an alarm or  
turn off the incoming water to the water heater when leakage  
is detected.  
HOT WATER TEMPERATURES REQUIRED FOR AUTOMATIC  
DISHWASHER AND LAUNDRY USE CAN CAUSE SCALD  
BURNS RESULTING IN SERIOUS PERSONAL INJURY AND/  
OR DEATH. THE TEMPERATUREAT WHICH INJURY OCCURS  
VARIES WITH THE PERSON'SAGEAND TIME OF EXPOSURE.  
THE SLOWER RESPONSE TIME OF CHILDREN, AGED OR  
DISABLED PERSONS INCREASES THE HAZARDS TO THEM.  
NEVERALLOW SMALLCHILDREN TO USEAHOT WATER TAP,  
OR TO DRAW THEIR OWN BATH WATER. NEVER LEAVE A  
CHILD OR DISABLED PERSON UNATTENDED IN A BATHTUB  
OR SHOWER.  
Sensors mounted in the drain pan that turn off the water supply  
to the entire home when water is detected in the drain pan.  
Water supply shutoff devices that activate based on the water  
pressure differential between the cold water and hot water  
pipes connected to the water heater.  
Devices that will turn off the gas supply to a gas water heater  
while at the same time shutting off its water supply.  
BLOCKED VENT SHUT-OFF SYSTEM  
The Boiler is equipped with a blocked vent shut-off system which  
will close the gas valve and shut off the main burner gas when  
there is excessive pressure in the vent system due to a partially  
or completely blocked vent system.  
THE WATER HEATER SHOULD BE LOCATED IN AN AREA  
WHERE THE GENERALPUBLIC DOES NOT HAVEACCESS TO  
SET TEMPERATURES.  
DO NOT ATTEMPT TO OPERATE THE BOILER if this situation  
occurs. Shut the boiler off before performing all the steps shown  
in "TO TURN OFF GAS TO APPLIANCE" section of the Lighting  
and Operating Instructions.  
Contact a qualified service agent to inspect the unit and vent  
system and correct the problem.  
VENT SYSTEM  
The flue products are corrosive in nature and if the boiler is  
vented horizontally the flue gases are at a higher pressure than  
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the surrounding air pressure. Inspection of the boiler and vent  
system is necessary to insure that flue gas leakage to the  
surrounding area does not occur.  
ELECTRONIC HOT SURFACE  
IGNITION CONTROL BOARD  
The EMC5000 control system is a fully integrated, state of the art  
electronic control system. It consists of sensors, output devices,  
a power switch, a 24vac transformer, wiring, and the following  
printed circuit boards:  
Inspect the external surfaces of the vent system every 3 months  
for corrosion and leakage. Inspect the vent terminations for  
corrosion and foreign matter which may be blocking the  
exhausting flue products. Call a qualified service agent to  
replace or repair any corroded or leaking parts.  
Central Control Board (CCB).  
Flame Control Board (FCB).  
User Interface Board (UIB).  
See Figure 1A.  
See Figure 1B.  
This part of the User Interface  
Module (UIM). See Figure 3.  
A qualified service agent must inspect the internal surfaces of  
the vent system and the boiler at least once a year.  
Power Distribution Board (PDB). See Figure 1C.  
Touch Sensor Board (TSB). This is part of the User  
BURNER SYSTEM  
Interface Module (UIM). See  
Figure 3.  
To maintain safe operation and the greatest efficiency for the  
boiler, observe the burner flame through the observation port on  
the jacket panel, once a month for proper flame characteristics.  
The CCB contains circuitry for both master control and flame  
control for the first stage. The FCB contains circuitry for flame  
control on up to one additional stage. Dip switches on the CCB  
and FCB are used to configure the system. The UIB and TSB  
are included in the User Interface Module (UIM) along with a 4  
line by 20-character LCD display. The PDB provides connection  
points for input power, the water pump, and the transformer. It  
also distributes power to the system and contains the system  
fuses.  
The burners should display the following characteristics:  
Provide complete combustion of gas.  
Cause rapid ignition and carry over across all burners and  
across the entire burner.  
Give quiet operation during ignition, burning and extinction.  
Cause no excessive lifting of flames from the burner ports.  
Dual stage control is accomplished by means of an internal  
communication network and the FCB's. One FCB is required for  
each stage beyond initial first stage. The CCB also contains an  
external communications system to allow for connection to a  
PC, a modem, or an EMS system. Through this connection  
multiple boilers can also be linked together.  
If the preceding characteristics are not evident, check for  
accumulation of lint or other foreign material that restricts the  
inlet air or burner ports. Ensure there is the proper amount of air  
to the burner. Flame lifting from the burner is caused by too  
much air to the burner.  
CAUTION  
The internal communications cables should never be connected  
to the external communications connectors and vice-versa.  
The burners must be inspected by a qualified service technician  
at least once a year.  
There are several microcontrollers used on the board. Three on  
the CCB, two on the FCB, and one on the UIB. These micros  
control the temperature and ignition control functions for the  
boiler. Inherent in the design are the normal operating sequences  
and safety features associated with a gas ignition control system.  
The system 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 display  
a red fault light as well as indicate the cause of the fault on the  
display. The operating programs for the system are stored in  
permanent memory inside the micros. User-selectable  
operating parameters and a history of detected faults are stored  
in re-writable memory in the micros. A loss of power does not  
affect either of the memories.  
DO NOT STORE COMBUSTIBLE MATERIALS, GASOLINE, OR  
OTHER FLAMMABLEVAPORS, LIQUIDS INTHE AREA OF THE  
APPLIANCE. NONCOMPLIANCE MAY RESULT IN FIRE OR  
EXPLOSION. DO NOT OBSTRUCT THE FLOW OF  
COMBUSTION ORVENTILATION AIRTOTHE APPLIANCE.  
CHEMICAL VAPOR CORROSION  
Boiler corrosion and component failure can be caused by  
airborne chemical vapors. Spray can propellants, cleaning  
solvents, refrigerants, calcium or sodium chloride (water softener  
salts), waxes, and process chemicals are typical compounds  
that are potentially corrosive. These materials are corrosive at  
very low concentration levels with little or no odor to reveal their  
presence. Products of this sort should not be stored near the  
boiler. Air which is brought in contact with the boiler should not  
contain any of these chemicals. The boiler should be provided  
with air from outdoors when installed in environments having  
corrosive atmospheres.  
Inputs To CCB and FCB:  
Temperature Sensors:  
Temperature probes (CCB - outlet and either inlet or tank is  
required): The CCB accepts analog temperature inputs from  
up to three sensors (inlet, outlet and tank).  
• ECO input (CCB - required):  
CIRCULATION PUMP  
The ECO (Energy Cut-Off) is a Hi-Limit switch, which is  
located inside the output probe. It is a normally closed switch  
that opens if the probe is exposed to a temperature higher  
than the trip point.  
• Thermostat input (CCB - optional):  
This input is set up to work with an externally connected  
thermostat that provides a contact closure. If this input is  
Refer to the pump manufacturer's schedule of maintenance for  
frequency and method of lubricating the pump and motor. Inspect  
the pump once a month for leaky mechanical seals and/or  
O-rings and loose or damaged components. Contact a qualified  
service agent to replace or repair parts as required.  
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Figure 1A. CCB  
(Drawing #211758)  
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