Flame Rollout Switch - Ducane CMP A Series Installation Instructions Manual

CAUTION
At elevations above 4,000 feet a change to the P1
(blocked vent) pressure switch may be required. If
a pressure switch change is necessary use the
proper Ducane pressure switch kit shown in Table
1.14.
?able 1.14 HIGH ALTIqT.IDE PRESSURE SW1TCH KITS
Model Kit Number
50
75U2
75U3A 20274501
75U3
I00
125 20274503
Altitude Installation (Canada ONLY):
Check with your local gas company and check for local code
requirements on altitude dernfing. For installation of this furnace
at an elevation above 2.000 ft (610m) see the rating label on the
front of this furnace for proper input and orifices size.
Limit Control Check:
After the furnace has been in operation for at least 15 minutes,
restrict the return air supply by blocking the filters or closing the
return registers and allow the furnace to shut down on high limit.
The main burners will shut OFF and the main blower and
combustion blower should continue to run. Remove the restriction
and the burners should come back on in a few minutes.
Flame Rollout Switch:
This unit is equipped with a manual reset fiame-rollout switch
that protects against improper venting of the flue gases from the
heat exchanger due to blockage within the furnace or vent system.
If such a blockage causes heat (or flames) to "rollout" into the
burner box from the heat exchangers, this safety device will
activate and shut off power to the automatic gas valve before there
is damage to the furnace. The loss of power to the gas valve will
shut off the gas burners. Should this occur, it will be necessary to
determine the cause of the rollout, correct the condition that caused
it, and reset the flame-rollout switch.
WARNING
Hand drilling of orifices is never acceptable since
it could lead to delayed ignition, overfLring,
improper combustion, flashback and, flame
roUout. All these conditions could leadto a fire
hazard and bodily harm, or loss of life.
Fan Adiustment Check:
This furnace is equipped with a 3 speed direct drive motor to
deliver a temperature rise within the range specified on the rating
label, between the return and supply plenums, at the external duct
static pressure noted on the rating label.
Adjust the fan speed so that the temperature rise is within the
rise specified on the rating plate. Consult the wiring diagram for
speed changes on the direct drive motor.
To adjust fan OFF time, set the DIP switches on the control
board as shown to obtain the desired timing (See Figure 2.14).
Figure 2.14 FAN OFF TIME ADJUSTMENT
00 s ocDELA ,o F?0 , P sw, oT . ,Nd 0
The switch located on the bottom of the burner box enclosure,
is accessed by removing the louvered front door from the furnace,
and is reset by pushing in the button in the middle of the switch
(between the two wire connections - see Figure 3.14). Very little
force is required to push the reset button, and a "click" should be
heard when the switch resets.
Figure 3.14 FLAME ROLLOUT SWITCH
I_L.LOOT
/
O O
O
z i"_7"i i
o o
_SET
20246506 Issue 9939 Page 14 of 22