Sterling QVSB - Manual (Page 16)

16
OPERATION
Never operate the unit beyond the
specified limits or severe damage to and/or
premature failure of the unit will result!
EXPLANATION OF CONTROLS
1. Each Separated Combustion Unit Heater comes
equipped with a power vent system that consists of
a power venter motor and blower, pressure switch
and sealed fl ue collector.
The addition of external draft hoods or
power venters is not permitted. Addition of such
devices may cause severe unit malfunction or failure!
2. The power venter motor is energized by the room
thermostat when a demand for heat is sensed. The
pressure switch measures the pressure differential
between the air inlet and exhaust vent systems. If
the differential is correct the indirect spark ignition
system is energized.
Under no conditions is the unit
to be fi red if the power venter is not operable or
severe personal injury or death may occur!
3. The indirect spark ignition system consists of an
ignition module, a dual combination valve, and a
spark-ignited pilot burner. When the pressure switch
is closed, the pilot valve opens as a spark is
generated to light the pilot. When the fl ame is
sensed by the fl ame sensing circuit the spark ceases
and the main gas valve is opened to supply gas to
the main burners. Once the thermostat has been
satisfied, the vent system and gas valve are
simultaneously deenergized stopping all gas fl ow to
the unit.
4. The limit switch interrupts the fl ow of electric current
to the main gas valve if the unit heater becomes
overheated.
5. The fan switch delays the operation of the fan for
approximately 45 seconds once the thermostat is
closed and continues fan operation for approximately
65 seconds after the thermostat opens.
NOTICE: The start-up fan delay must not exceed 90
seconds from a cold start.
6. The wall thermostat, supplied optionally, is a
temperature sensitive switch that operates the vent
and ignition systems to control the temperature of
the space being heated.
NOTICE: The thermostat must be mounted on a
vertical, vibration-free surface free from air currents
and in accordance with the furnished instructions.
INITIAL LIGHTING
1. Open the manual gas valve, in the gas supply line to
the unit heater. Loosen the union in the gas supply
line to purge it of air. Tighten the union and check for
leaks.
Check all pipe joints for leakage
using a soap solution or other approved method.
Never use an open flame to detect leaks.
Explosive conditions may exist which could result
in property damage, personal injury or death!
Before attempting to light or
relight the pilot, wait 5 minutes to allow gas
which may have accumulated in the burner
compartment to escape. Failure to heed this
warning could result in property damage,
personal injury or death!
2. Turn on the electrical power. The unit heater should
now be under the control of the thermostat. Set the
thermostat to it's highest setting; the power venter
motor should start and burner ignition occur. Allow
the unit heater to operate until the fan starts, then
set the thermostat to it's lowest setting. The burners
and power venter motor should stop operating
immediately while the fan continues to operate until
the fan time delay times out, shutting it off. Reset
the thermostat to the desired operational setting.
CHECKING UNIT HEATER GAS INPUT RATE
Never overfi re the unit heater, as this
may cause unsatisfactory operation, or shorten the
life of the heater.
Gas appliances are rated based on sea level operation,
with no adjustment required at elevations up to 2000
feet (610m). At elevations above 2000 feet (610m), input
ratings should be reduced by 4% for each 1000 feet
(305m) above sea level. Check the input rate as follows:
1. Turn off all other gas appliances that utilize the
same gas meter as the unit heater.
2. Let the unit heater run for 15 minutes.
3. Using the gas meter, clock the time that it takes to
burn 1 cubic foot of gas.
4. Insert the time, in seconds, into the formula below.
RATE in = HEATING VALUE(BTU/FT 3 )(3600S/HR)
Time (s/ft 3 )
EXAMPLE: If: heating value = 1000 BTU/ft 3
time/ft 3 = 18 s/ft 3
RATE in = (1000 BTU/ft 3 ) (3600 s/hr)
18 s/ft 3
RATE in = 200,000 BTU/hr
(Refer to “General Safety Information” section
for metric conversions).