MN702GE 060320
– 21 –
12.
With the burner running in high fire, adjust the main gas pressure
regulator to achieve:
•
Natural gas: 9.6% to 10.0% CO
2
.
•
Propane: 10.7% to 11.2% CO
2
.
•
Measure the CO content. It should be no greater than 100 PPM.
High CO readings may indicate the combustion is on the wrong
side of the CO
2
. curve. You will know this if a decrease in gas
pressure causes an increase in CO
2
.
Step 3
Set butterfly gas valve linkage
1.
Switch the low-fire hold switch to low fire.
2.
Check CO
2
and CO. The CO
2
should be between 9.0% and 10.0% (natural
gas) or between 10.0% and 11.2% (propane); with CO less than 100 PPM.
3.
To adjust the low-fire air (change CO
2
), move the burner fuel selector
switch to OFF. Adjust the butterfly gas valve linkage as described in
the following to change the low-fire gas flow to the burner head. Do not
change the main gas pressure regulator setting.
4.
DO NOT ADJUST THE LOW-FIRE AIR DAMPER SETTING.
5.
See Figure 13 for location of linkage components.
Figure 13
Butterfly gas valve linkage
7. Adjust the burner using test instruments
(continued)
To adjust the linkage, loosen set screw in the adjustable link in
small increments. A 1/8-inch move can cause CO
2
to change
as much as 1.5%.
•
If more gas is needed (to increase CO
2
), slide linkage UP.
•
If less gas is needed (to decrease CO
2,
), slide linkage DOWN.
6.
Tighten the set screw in the adjustable link.
7.
The butterfly valve indicator must be at 90°. IF NOT, turn the burner
off. Loosen the two hex-head screws securing the valve linkage arm.
Rotate the butterfly valve indicator until it is at 90°. Disengage actuator
motor. Rotate linkage to high fire. Tighten the two hex head screws while
still holding the motor linkage arm in high fire. Rotate linkage to low fire.
Re-engage pin.
8.
Tighten the two hex head screws on the butterfly valve linkage arm boss.
9.
Restart and repeat as necessary until CO
2
and CO are acceptable.
IF EQUIPPED WITH LOW-HIGH GAS PRESSURE SWITCH,
PROCEED TO STEP 3A.
OTHERWISE PROCEED TO STEP 4.
Step 3a
Verify operation
Perform all of the checkout procedures given in Steps 3A-4 of the
burner manual. In addition, verify operation of the gas pressure
switches as described below.
Verify high gas pressure switch operation
❏
Cycle the burner off with the appliance controls and turn off power to the
appliance/burner.
❏
Attach a manometer to the manifold-side manual gas valve test port.
❏
Turn on power and cycle the burner on with the appliance controls.
❏
Measure the manifold gas pressure with the manometer.
❏
Set the high gas pressure switch to a pressure less than actual manifold
pressure. The high gas pressure switch should shut the burner down.
Replace the switch if necessary.
❏
Turn off power to the appliance/burner; remove the manometer and replace
the plug in the gas valve test port. Reset switch.
Verify low gas pressure switch operation
❏
Cycle the burner off with the appliance controls and turn off power to the
appliance/burner.
❏
Close the main manual gas valve.
❏
Cycle the burner on.
❏
The low gas pressure switch should shut the burner down. Replace the
switch if necessary.
❏
Turn off power to the appliance/burner.
❏
Open the main manual gas valve.
❏
Reset low gas pressure switch.
Hex
Nuts
(not shown)
Butterfly
Valve
Indicator
(red needle)
Set
Screw