IM 972-2 • MAVERICK I ROOFTOP SYSTEMS 38 www.DaikinApplied.com
Controls and Operation
Controls and Operation
Furnace Section Controls and Ignition System
Normal Furnace Operating Sequence
This unit has a two stage gas furnace which employs an
integrated furnace control with self diagnostics located in the
control box. The furnace is composed of induced draft blowers,
negative pressures switches, two stage gas valve, manifold
orifices, in-shot burners, direct spark ignitor, remote flame
sense, tubular heat exchanger, high limit switch and rollout
switches. See
Normal Heat Mode
Call For First Stage (low fire) Only:
1.
Zone thermostat contacts close, a call for first stage (low
fire) heat is initiated.
2. Control runs self check.
3. Control checks the high-limit switch for normally closed
contacts, each pressure switch for normally open
contacts, and all flame rollout switches for continuity.
4.
Control energizes each low-fire inducer.
5.
Control checks each low-fire pressure switch for closure.
6. If each pressure switch is closed, the control starts a
30 second prepurge and energizes W2. If any pressure
switch is still open, the inducers will continue to be
energized until closure.
7. After prepurge timeout, control energizes W1 and
continues to energize W2, initiates spark for two
seconds minimum (seven second maximum) ignition
trial, and initiates a 120 second - second stage (high
fire) warm up timing.
8.
Control detects flame, de-energizes spark and initiates
45 second delay on blower timing.
9.
After a fixed 45 seconds indoor blower delay on, the
control energizes the indoor blower.
10.
After a fixed 120 seconds second stage warm-up period
control checks thermostat input. If only W1 is called for,
W2 is de-energized and the control starts a 30 second off
delay on the W2 inducer(s).
11.
After fixed 30 seconds the W2 inducer is de-energized.
12. Control enters normal operating loop where all inputs are
continuously checked.
13.
Zone thermostat is satisfied.
14. Control de-energizes gas valve.
15.
Control senses loss of flame.
16.
Control initiates five second inducer post-purge and 90
second indoor blower delay off.
17. Control de-energizes inducer blower(s).
18. Control de-energizes indoor blower.
19. Control in the stand by mode with solid red LED.
Figure 36: Heat Exchanger Component Identification
Summary of Contents for Maverick I
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