Honeywell S7999D1048 Manual page 34

S7999D1048 COMBUSTION SYSTEM OPERATOR INTERFACE DISPLAY
Auxiliary Sensor Configuration
The first page that displays after the "System Configuration"
button is selected is shown in Fig. 64 and 65.
Fig. 64. Setting Auxiliary Sensor Parameters.
Fig. 65. Auxiliary Sensor Configuration—Set Minimum
Degrees.
Select an Operation:
1. Disabled means the input is ignored.
2. Low Fire Hold—Selecting this option field enables an
algorithm that protects the boiler from thermal shock.
Upon successful progression to modulation, the
R7999 holds the burner at the lightoff point until the
auxiliary temperature input exceeds the programmed
threshold.
3. FGR Hold—After successful progression to modulation,
the R7999 holds the FGR closed until the auxiliary
temperature input exceeds the programmed threshold.
4. FGR and Low Fire Hold—Selecting this option enforces
both of the above actions.
a. Max (20 mA)—This field lets you set the maximum
sensing range of the transducer. The maximum value
must be between -40°F and 1400°F.
b. Min (4 mA)—This field lets you set the minimum
sensing range of the transducer. The minimum must
be less than the maximum by at least 100°F.
65-0321—01
c. Threshold—This field lets you set the threshold tem-
perature at which you want the low fire hold or FGR
hold or Low Fire and FGR hold to be released. The
threshold temperature must be less than the maxi-
mum and greater than the minimum.
d. Differential—This field lets you set the differential
temperature at which the system will revert to a hold
condition. The threshold must be set lower than the
threshold but greater than the minimum.
Remember to press the Set button before moving to a different
page.
When the "Next" button is selected, the following figure
displays.
Fig. 66. Miscellaneous Commissioning Parameters.
Controller timing: Postpurge Timeout—Select how long the
system should wait at the postpurge position once the
postpurge state has been detected. It is important that the
postpurge timeout time be at least as long as the burner
control time, especially when the air damper is configured to
close while in standby.
Auto/Manual Switch
a. Select either Normal or Maximum Firing Rate Limit.
b. When the Maximum Firing Rate Limit is selected, the
R7999 (when in auto mode) reads the value of the
manual potentiometer input and does not allow
modulation beyond its interpreted value. The manual
potentiometer input equates 0 to 500 ohms as a 4
mA firing rate input and 4500 ohm or greater as a 20
mA input; all other values are determined by linear
interpolation. The behavior during manual switch
setting is not affected, i.e., the firing rate input is
derived directly from the potentiometer value and the
controller mA input is ignored.
FGR Behavior During Purge—Lets you set the position of the
FGR actuator during the purge cycle. The options are Remain
Closed or Follow FGR Curve to Purge Position.
Remember to press the Set button before moving to a different
page.
When the "Next" button on this page is selected, the following
page displays.
34