Mestek IIEB-11, Installation & Parts Manual

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16
OPERATION
POWER VENTED BLOWER UNITS
INTERMITTENT (SPARK) PILOT IGNITION
EXPLANATION OF CONTROLS:
1. The unit heater is equipped with a dual automatic
gas valve and electric ignition device (separate from
the gas valve on most models) which provide the
following functions:
a. The unit heater is equipped with a power vent
system consisting of a power venter motor
and blower, pressure switch, and sealed flue
collector in place of the conventional draft
diverter.
The addition of external draft hoods
or power venters is not permitted. Addition of such
devices may cause severe unit malfunction or
failure!
b. The power venter motor is energized by the
room thermostat on a call for heat. The pressure
switch measures the flow through the vent
system and energizes the indirect spark ignition
system when the fl ow is correct.
The pressure switch MUST
NOT be bypassed. The unit MUST NOT be fi red
unless the power venter is operating. An unsafe
condition could result.
c. The indirect spark ignition system consists of
an ignition control module, a dual combination
gas valve, and a spark-ignited pilot burner.
When the pressure switch closes, the pilot
valve opens and a spark is generated to light
the pilot burner. When the fl ame sensing circuit
senses that pilot fl ame is established, the main
gas valve is opened to supply gas to the main
burners. When the thermostat is satisfi ed, the
vent system is de-energized and both valves
are closed to stop all fl ow of gas to the unit.
d. Pilot solenoid valve also functions as a main gas
valve to provide redundancy.
e. Pressure regulator provides proper and steady
gas pressure to the main burners.
f. Manual shutoff valve for service and long term
shut-down. (Separate from the automatic valve
on some models.)
2. The limit switch interrupts the fl ow of electric current
to the main gas valve in case the heater becomes
overheated.
3. The fan switch delays the operation of the fan until
the heater is warmed, then keeps the fan running
after the gas has been turned off until the useful
heat has been removed. The start-up fan delay
must not exceed 90 seconds from a cold start.
4. The wall ther mostat (supplied optionally) is a
temperature sensitive switch which operates the
vent system and ignition system; it turns the main
gas valve ON or OFF to control the temperature
of the space being heated. It must be mounted
on a vibration free, ver tical surface away from
air currents, in accordance with the instructions
fur nished with the ther mostat (also refer to
Electrical Section).
START-UP
1. Open the manual valve supplying gas to the unit
heater, and with the union connection loose, purge
air from the gas line. Tighten the union and check
for gas leaks, using a soapy water solution only.
Never use an open fl ame to detect
gas leaks. Explosive conditions may exist which
could result in personal injury or death.
Before attempting to light or
relight pilot, wait 5 minutes to allow gas which
may have accumulated in the burner compart-
ment to escape. Failure to do so could cause
the accumulated gas to ignite rapidly, leading to
personal injury or death.
2. Open the manual valve on the unit heater.
3. Turn ON electrical power.
4. The unit should be under the control of the
thermostat. Turn the thermostat to the highest point
and determine that the power venter motor starts
and the pilot and main burners ignite. Turn the
thermostat to the lowest point and determine that
the power venter motor shuts off and pilot and main
burners are extinguished.
5. If pilot adjustment is required, remove the pilot
adjustment seal cap and adjust the pilot screw to
obtain proper fl ame. Clockwise rotation decreases
pilot fl ame size. Replace the cap.
6. Turn the thermostat to the desired position.
7. Refer to “Adjustments” section for more specifi-
cations.
SHUT DOWN
1. Turn the valve selector knob to the “OFF” position.
2. Turn off the electricity.
3. To relight, follow the “start-up” instructions.
See Figure 17 for parts/identifi cation.