AAON HB-005 - Manual (Page 27)

27
Heating Sequence
On a call for heating, the supply fan will go to high
speed, and the first stage of heating will be energized.
The unit will go through a 5 second pre-purge of air in
the heat exchanger, then it will come on, or ignite if
gas heat. If the unit has a second heating stage, then
stage two will come on with a call for W2 after the
stage up delay. If W2 is called for before W1, then
heat stage one will come on first, then heat stage two
will follow after the stage up delay.
High Temperature Cut-off
If the supply air temperature (SAT) rises above the
150
°F limit, then the heating will stage off, but the
supply fan will continue to operate on low speed until
the SAT falls below 80
°F, at which point the heat will
come back on. If the SAT rises above the limit a
second time (consecutively) during a heating call, then
the heat will lock out. To restore normal operation,
remove the call for heating, or cycle the power.
Low Temperature Cut-off
If the supply air temperature (SAT) falls below the
40
°F limit, then the outside air damper will close. If the
SAT remains below the low limit for 15 minutes, then
the heating, and supply fan will be locked out. To
restore normal operation, remove the call for heating,
or cycle the power.
Safety Lock Out
The standard heating safety devices used as part of
the Heat Safety Monitor are MLS, ALS, ROS, and
DPS. If any of these devices trip 3 times during a
heating call, then the heating will be locked out. To
restore normal operation, remove the call for heating,
or cycle the power.
Chilled Water
Check remote chiller operations as per the
manufacturer’s instructions. Check coolant flow valves
for correct operation and settings.
Filters
Open the filter access door. Slide filters towards you
to inspect. Replace old filters with the size indicated
on each filter. Be sure arrow points toward the blower.
Filters should be checked every 30 days and replaced
or cleaned as necessary.
IT IS IMPORTANT TO KEEP FILTERS, COILS, AND
BLOWERS CLEAN!
Unit Size (Tons) Size Depth
2 – 5 20” x 25” 2”
Figure 27a, Filter Section
Cleaning
Inspect and clean unit interior at the beginning of each
heating and cooling season and as operating
conditions require
.
Service
In the event the unit is not functioning correctly and a
service company is required, only a company with
service technicians qualified and experienced in both
heating and air conditioning should be permitted to
service the systems in order to keep warranties in
effect. The service tech may call the factory if
assistance is required.
BEFORE CALLING, THE MODEL AND SERIAL
NUMBER OF THE UNIT WILL BE NEEDED FOR THE
WARRANTY SERVICE DEPARTMENT TO HELP
ANSWER QUESTIONS REGARDING THE UNIT.
AAON Warranty Department: 918-583-2266
Table 27.1, Filter Sizes