Checking For Delayed Ignition; Checking For Flashback; Checking Pressure Control; Pressure Switch Operation - Daikin M Series Service And Troubleshooting

SERVICING
Adjust manifold pressure using the Manifold Gas
Pressure table shown below.
Manifold Gas Pressure
Gas
Natural Low Stage
High Stage
Propane Low Stage
High Stage
8. Remove regulator cover screw from the low (LO)
outlet pressure regulator adjust tower and turn screw
clockwise to increase pressure, or counterclockwise
to decrease pressure.
9. Energize main (M) solenoid as well as the HI terminal
10. Remove regulator cover screw from the HI outlet
pressure regulator adjust tower and turn screw clock-
wise to increase pressure, or counterclockwise to
decrease pressure.
11. Turn off all electrical power and gas supply to the
system.
12. Remove manometer hose from outlet pressure boss.
13. Turn outlet pressure test screw in to seal pressure
port (clockwise, 7 in-lb minimum).
14. Turn on electrical power and gas supply to the sys-
tem.
15. Turn on system power and energize valve.
16. Using a leak detection solution or soap suds, check
for leaks at pressure boss screw. Bubbles form-
ing indicate a leak. SHUT OFF GAS AND FIX ALL
LEAKS IMMEDIATELY.
NOTE: Use adapter kit #0151K00000S to measure gas
pressure on White-Rodgers 36G54 gas valves.
Line voltage now present

Checking For Delayed Ignition

Delayed ignition is a delay in lighting a combustible mixture
of gas and air which has accumulated in the combustion
chamber.
When the mixture does ignite, it may explode and/or rollout
causing burning in the burner venturi.
If delayed ignition should occur, the following should be
checked:
1. Improper gas pressure - adjust to proper pressure.
2. Improper burner positioning - burners should be in
locating slots, level front to rear and left to right.
3. Carry over (lighter tube or cross lighter) obstructed -
clean.
4. Main burner orifice(s) deformed, or out of alignment
to burner - replace.
Range Nominal
1.7 -2.3" W.C. 2.0" W.C.
3.2 - 3.8" W.C. 3.5" W.C.
5.7 - 6.3" W.C. 6.0" W.C.
9.7 - 10.3" W.C. 10.0" W.C.
WARNING

Checking For Flashback

Flashback will also cause burning in the burner venturi, but
is caused by the burning speed being greater than the gas-
air flow velocity coming from a burner port.
Flashback may occur at the moment of ignition, after a
burner heats up or when the burner turns off. The latter is
known as extinction pop.
Since the end results of flashback and delayed ignition
can be the same (burning in the burner venturi) a definite
attempt should be made to determine which has occurred.
If flashback should occur, check for the following:
1. Improper gas pressure - adjust to proper pressure.
2. Check burner for proper alignment and/or replace
burner.
3. Improper orifice size - check orifice for obstruction.

Checking Pressure Control

A pressure control device is used to measure negative
pressure at the induced draft blower motor inlet to detect a
partial or blocked flue.

Pressure Switch Operation

(DSI Direct Spark System)
The pressure switch is ignored unless there is a call for
heat. When the control receives a call for heat, the control
checks to see that the pressure switch is open. If the
control sees that the pressure switch is closed before the
induced draft blower is energized, the LED will flash a code
of "2" (to indicate the pressure switch is stuck closed) and
the inducer will remain off until the pressure switch opens.
If the pressure switch opens before the ignition period, the
induced draft blower will remain on and the control will stay
in pre-purge until the pressure switch is closed for an entire
15 second pre-purge period. The LED will flash a code of
"3" to indicate open pressure switch.
If the pressure switch opens after the gas valve has been
energized, the control will de-energize the gas valve and
run the indoor blower through the heat off delay. The
inducer stays on until the pressure switch re-closes. Then
the control makes another ignition attempt.
High Voltage!
Disconnect all power before servicing or
installing. Multiple power sources may be present.
Failure to do so may cause property damage,
personal injury or death.
1. Remove wires from the electrical terminals.
2. Using a VOM check from Common to NO (Normally
Open) - should read open.
If switch reads as noted proceed to Step 3, otherwise
replace control.
WARNING
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