Wayne HSG200 User Manual - page 29
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restart the system, the main power or thermostat must be de-energized momentarily, then re-energized. If
at any time during the heat cycle, there is insufficient supply of combustion air to the burner, the air switch
contacts will open, putting the system into lockout closing gas valve.
See Figure 27 for wiring diagram of HSG Series Burner utilizing the Honeywell S89E control.
SEQUENCE OF OPERATION
– HSG SERIES POWER GAS CONVERSION BURNER
UTILIZING HONEYWELL S89F P/N 62759-002 IGNITION CONTROL W/BUILT IN 30 SECOND PRE-
PURGE
On a call for heat, voltage (24V) is applied to the motor start relay and air switch. Once the fan motor
reaches operating rpm, combustion air pressure causes the air proving switch to close, and the contacts
energize the ignition control.
The ignition control has an internal 30 second pre-purge timer. After the initial 30 second pre-purge, the
ignition control simultaneously energizes the gas valve and ignition transformer. Gas flows to the burner
head and the transformer produces a spark at the electrode establishing main burner flame.
At the start of each heat cycle, there is a trial for ignition period of four (4) seconds duration. Normally,
burner flame will be established before the end of this period. Once the flame is established and sparking
ceases, the flame sensor will provide flame monitoring to the ignition control for the remainder of the heat
cycle. If the flame should be extinguished during the heat cycle, the S89F ignition control will go into the 30
second pre-purge and 8 second safe start check, then re-energize the gas valve and ignition transformer in
an attempt to establish the main burner flame. If reignition does not occur within the trial for ignition period,
the ignition control will go into lockout de-energizing the gas valve and ignition transformer.
To restart the system, the main power or thermostat must be de-energized momentarily, then re-
energized. If at any time during the heat cycle, there is an insufficient supply of combustion air to the
burner, the air switch will open, putting the system into lockout closing the gas valve.
See Figure 28 for the wiring diagram for HSG Series burners using the Honeywell S89F control
FLAME SENSING ON HSG SERIES BURNERS
The ignition control utilizes the flame current rectification principal for main burner flame sensing.
The flame rectification phenomenon occurs as follows: The ignited gas flame causes the immediate
atmosphere around the flame to become ionized (gas atoms become electrically charged). The ionization
causes the atmosphere around the flame to become electrically conductive. An ac voltage output from the
ignition control sensing circuit is routed through the flame sensor probe. When the flame sensor probe and
burner head are both in contact with a properly adjusted flame, the burner head with its larger surface
attracts more free electrons, thus becoming negatively charged. The flame sensor probe with its small
surface area gives up free electrons, thus becoming positively charged. The free electrons from the ac
voltage in the flame sensor probe flow through the ionized gas flame to the grounded burner head. As the
ac current passes through the gas flame, it is rectified into a dc current flowing back to the grounded side
of the sensing circuit. The flame in actuality is a switch. When the flame is present the switch is closed
allowing current to flow through the sensing circuit of the control. When no flame is present, the switch is
open with no current flowing through the sensing circuit of the control.
The dc current flow is measured in units called dc microamperes. This current can be measured by
disconnecting the wire from the Sense terminal and connecting the probes of a meter that can measure
microamps between that wire and the sense terminal. A steady dc microampere current of 0.2 minimum (.8
microamps for Honeywell controls) or higher through the sensing circuit of the primary ignition control is
sufficient to keep the burner running without a safety lockout. See Figure 20 for flame current
measurement.