EngA ENGINEERED AIR base - Dg Indirect Fired; Basic Operation; Dg Timing

base A
23
IOM74 November 2020 R105
DG INDIRECT FIRED
For indirect heating appliances with DG and DJX200/300.
BASIC OPERATION
On a call for heating the combustion blower will be enabled and the air actuator will open to the prepurge
setpoint to purge the heat exchanger. Once the prepurge time has elapsed the gas and air actuators will move
to ignition position and then enable the ignition control to start pilot flame. Once ignition is proven, it will then
open the main safety valve (SSOV). Once the pilot flame has been proven and the main flame is established, the
base will then disable the pilot valve. The burner is allowed to operate to maintain the requested discharge air
temperature from the base by modulating the gas and air actuators. If heating is not required the burner will
be disabled and the combustion blower will enter a post purge time, and then shut down.
DG TIMING
Prepurge
60 seconds
.
Post purge
5 minutes
.
Flame failure
15 seconds lockout on ignition control and 60 seconds on burner
.
Pilot opening time
8 seconds
.
Open combustion air proving
6
0
seconds
.
Improper gas valve wiring
5
seconds
.
Blocked condensate trip
5 minutes
.
Blocked flue
10 seconds trip and 1 minute burner alarm
.
Heat exchanger cool down
90 seconds if the discharge air is above 50° (10°C), else none.
Heat exchanger warm up
fan
delay
75 seconds if ambient air is less than 40°F (4°C) and discharge temperature
less than 90°F (32°C), else warm up is not required.
Burner cool down
90 seconds
.