16
SERVICING
PROCEDURES
General Location of Controls
Sequence of Operation
Intermittent Ignition Device (IID)
Heaters equipped with the IID system will automatical-
ly light the pilot burner first and then the main burner,
each time there is a call for heat from the tankstat.
Whenever the tankstat calling for heat, the circulator
supplied with the heater, will be energized and should
be running.
The ignition control module will also be energized to
initiate the pilot ignition by opening the first main valve
(pilot). At the same time, the electronic spark genera-
tor in the module produces a high voltage spark pulse
output that lights the pilot burner. If the pilot burner
does not light, the module will not energize the second
main valve and the burners will not light. Ignition spark
continues only until the timed trial for ignition period
ends.
Then, the module goes into safety shutdown or lock-
out. Lockout de-energizes the first main valve operator
and closes the first main (pilot) valve in the gas con-
trol, stopping pilot gas flow. The ignition control system
must be reset by setting the tankstat below water tem-
perature for one minute or by turning off power to the
module for one minute.
When the pilot flame is established, flame rectification
circuit is completed between the sensor and burner
ground. The flame sensing circuit in the module
detects the flame current, shuts off the spark genera-
tor and energizes the second main valve operator
which opens the second main valve. This allows gas to
flow to the burners where it is ignited by the pilot burn-
er flame.
When the tankstat is satisfied, the valve operators are
de-energized shutting off the pilot and main burners,
and also the circulator.
Start-up Procedures
Filling the System
Fill system with water. Purge all air from the system
using purge valve sequence. After system is purged of
air, lower system pressure. Flush system before put-
ting into operation to ensure that foreign material does
not damage pump seals.
Checking the Circulator
Before lighting the heater and after system is filled,
make sure that circulator is operating properly. Manual
gas valve should be off.
NOTE:
Circulator motor supplied with the heater
does not require lubrication.
Ignition Module
(Auto Ignition Only)
Fig.# 8195.3
Circulator
Manual Reset Limit
(in heater behind panel)
Pressure
Relief Valve
Field Wiring
Compartment
Temperature Sensor
Ignition Module
(Auto Ignition Only)
Transformer
Roll-Out Sensor
Gas Valve
Fig. 8: General Location of Controls
