A.O. Smith GPSH, GPCR owner manual Maintenance, Water Heating Ignition Sequence, Main Burner -FIG

WATER HEATING IGNITION SEQUENCE

(Make sure gas and electric power are connected properly)

1)The ignition control module is powered and monitors the system, waiting for a call for heat from the thermostat.

2)The thermostat calls for heat by reading a resistance value within a given range directly proportional to water temperature.

3)The control Module:

a)Checks the pressure switch for an open circuit.

b)Energizes the blower.

c)Checks the pressure switch for a closed circuit to prove draft.

d)Sends line voltage to the hot surface igniter with a 20 second warm up period.

e)Opens the gas valve and checks the sensing rod for flame.

4)The burner heats the water to the desired thermostat setting.

a)The resistance in the thermostat rises to the value selected by the temperature setting.

b)The control module closes the gas valve and 5 seconds later, removes power from the blower.

5)Cycle is completed.

FIGURE 10

CONTROL SEQUENCE - HOT SURFACE DIRECT IGNITION

Pre-purge	5	seconds.
HSI Warm-up	20	seconds.
Ignition Activation Period	4	seconds.
Flame Recognition Period	1	second.
Ignition Trial	4	seconds.
Interpurge	5	seconds.
Post-purge	5	seconds.
Retries	2
Reset from Lockout	1	hr.
Flame Sensing (Nominal)
HSI Off/Run Mode	4.0µV DC

MAINTENANCE

WARNING

DISCONNECT FROM ELECTRICAL SUPPLY BEFORE SERVICING UNIT.

FOR YOUR SAFETY, WATER HEATER SERVICE SHOULD BE PERFORMED ONLY BY A QUALIFIED SERVICE TECHNICIAN. READ THE GENERAL SAFETY INFORMATION SECTION FIRST.

USERS OF THIS APPLIANCE SHOULD BE AWARE THAT GAS COMPONENTS WEAR OUT OVER A PERIOD OF TIME. THE GAS CARRYING COMPONENTS OF THIS APPLIANCE SHOULD BE INSPECTED FOR PROPER OPERATION PERIODICALLY BY A QUALIFIED SERVICE TECHNICIAN.

MAIN BURNER -FIG. 1

Check main burner every 12 months for proper flame characteristics. This is done by removing door(s) on heater, fig. 1. The main burner should provide complete combustion of gas; ignite rapidly; give reasonably quiet operation; cause no excessive flame lifting from burner ports. Make sure that the flow of combustion and ventilation air is not blocked.

If proper flame characteristics are not evident, check for accumulation of lint or other foreign material that restricts or blocks the air openings in the heater or burner. Also check AIR REQUIREMENTS.

WARNING

SOOT BUILD-UP INDICATES A PROBLEM THAT REQUIRES CORRECTION BEFORE FURTHER USE. Consult with a qualified service technician.

Should the main burner or burner air openings require cleaning, turn the blower switch to “OFF” position and allow the burner to cool. Remove the burner and clean with a soft brush. Clean main burner orifice with a suitable soft material.

HIGH TEMPERATURE LIMIT SWITCH

(Single-Use Type Energy Cut Off)

The thermostat has a built-in limit switch which will actuate in case of excessive water temperatures. The heater cannot be operated until the Gas Control Valve is replaced It is important that a serviceman be called to determine the reason for limit operation and thus avoid repeated thermostat replacement. Lower the temperature adjustment setting on new control.

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