Specifications

25
MAINTENANCE
Air Shutter Adjustment Procedure
It is very important that each burner assembly ignite and
burn with an orange (infrared) flame within 2 minutes of
ignition. The air shutters have been factory set, but no
ignition or a blue flame indicates that an air shutter
adjustment is necessary per this procedure.*
If, during regular maintenance or at any other time, it is
found that a burner does not ignite or the burner flame is
not orange, the following procedure must be used.
1. Remove electrical power from the GTS and manually
close off the gas valves by turning the gas valve knob
to “OFF” as shown in figure 33-1.
2. Open the gas valve for the burner needing adjustment
by turning the gas valve knob to “ON” and restore
electrical power.
3. Generate a call for humidity. If your GTS
®
has a
humidity transmitter, adjust the desired humidity on
the Zone Terminal Control Unit keypad (Set % RH) to
be 10% higher than the actual humidity (Actual % RH).
If your GTS is equipped with a humidistat, adjust the
humidistat setpoint to 10% above the actual humidity
level. If your GTS is being controlled by an energy
management system, use it to generate a call for
humidity.
4. The burner will try to fire in about 30 to 60 seconds.
Ignition will be tried three times, if ignition is not
achieved, remove the call for humidity, slightly close
the air shutter on the respective blower and reinstate
the call for humidity. Repeat this process until ignition
occurs. (An alternative to removing and reinstating
the call for humidity is to remove and reinstate the
24VAC power to the respective G750 ignition control-
ler for the burner being adjusted. To do this, discon-
nect the wire at the terminal marked “THS” for about 5
seconds and then reconnect it. See figure 25-1. The
burner will then repeat the ignition sequence. The
layout of the G750 ignition controllers is the same as
the layout of the burners, that is, upper left burner is
upper left G750 ignition controller, etc.)
5. After ignition is achieved, open the air shutter in 1/16”
to 1/8” perimeter increments until the orange glow
disappears and only the blue flame remains.
NOTE: Always allow at least two minutes between
adjustments to allow burner color to stabilize.
6. Once the orange glow has stopped and only the blue
flame remains, the air should be reset to the last air
shutter setting prior to the burner turning blue.
Observe this setting for a minimum of two minutes to
verify that the orange glow returns to the burner.
7. Remove and reinstate the call for humidity. Verify the
burner ignition.
8. Repeat this sequence of steps on all the burners that
will not light or fail to glow orange.
9. Turn all gas valves to the “ON” position.
NOTE:
• When the infrared burner glows orange, it is said to
have “gone infrared.” This is the burner’s most
efficient mode of operation.
• The time it takes for the burner to glow orange may
be longer than 2 minutes if the water in the tank is
cold.
• The lock nut at the center of the blower air shutter
should be tightened after each shutter adjustment.
• Closing the air shutter too far will result in improper
burner operation.
* If no ignition occurs, first verify the hot surface ignitor
is glowing during an ignition cycle. If a glow is not seen
through the sight glass prior to the gas valve opening
then the hot surface ignitor needs to be replaced.
Figure 25-1: Typical Ignition Controller
THS
OM-854
GTS-IOM-1298.pdf 25 11/17/2009 3:57:05 PM