Controls And Operation; Furnace Section Controls And Ignition System; Normal Furnace Operating Sequence - Daikin Maverick I Installation And Maintenance Manual

Controls and Operation

Furnace Section Controls and
Controls and Operation
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 Figure
Figure 37: Heat Exchanger Component Identification
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.
40
37.
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.
Call For Second Stage, After First Stage Established; Starting
from A.11:
1
If a call for second stage (high fire) is initiated after a call
for first stage heat is established, the control energizes
the W2 inducers and energizes the second stage of the
gas valve.
2
Control enters normal operating loop where all inputs are
continuously checked.
Second Stage Satisfied; First Stage Still Called For; Starting
From B.3:
1
Once the call for second stage is satisfied, the control
starts a 30 second off delay on W2 inducers and reduces
the gas valve to first stage.
2
Control enters normal operating loop where all inputs are
continuously checked.
First Stage Satisfied:
1
Zone thermostat is satisfied.
2
Control de-energizes gas valve.
3
Control senses loss of flame.
4
Control initiates five second inducer post-purge and 90
second indoor blower delay off.
5
Control de-energizes inducer blower.
6
Control de-energizes indoor blower.
7
Control in the standby mode with solid red LED.
First Stage and Second Stage Called Simultaneously:
1
Zone thermostat contacts close. A call for first stage (low
fire) and second stage (high 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.
Daikin IM 972-1