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Lennox ZGB Series - System Service and Maintenance Checks; Gas Flow, Flame Sensing, and Heat Exchanger; Cooling System Service Checks

Lennox ZGB Series
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
5-Proper Gas Flow
Furnace should operate at least 5 minutes before check-
         -


table 12. Seconds in table 12 are based on a 1 cu.ft. dial

         
time needed.
NOTE - To obtain accurate reading, shut o all other gas
appliances connected to meter.
TABLE 12
GAS METER CLOCKING CHART
Unit Input



Natural 
1 cu ft
dial
2 cu ft
dial
1 cu ft
dial
2 cu ft
dial
 55   277
   111 222
 33   
 31   
    
    
 21  53 
    
 15   75
   35 
    
   

Note: Table assumes standard temperature (60°F), pres-
sure(30in.Hg.), and fuel heating values (Btuh/Ft.3). Apply
pressure corrections in altitudes above 2000 ft.
IMPORTANT
Disconnect heating demand as soon as an accurate
reading has been obtained.
6-Heat Exchanger
Visually inspect heat exchanger. If replacement is neces-
sary refer to the instruction provided with the replacement
kit.
7-Flame Sensing
Flame current is an electrical current which passes from
the ignition control through the sensor electrode during unit
operation. The current passes from the sensor through the
-




NOTE-Electrodes are not eld adjustable. Any alterations
to the electrode may create a hazardous condition that
can cause property or personal injury.
1 - Disconnect power to unit.
2 -       
     
sensing electrode and the sensing lead.
3 - 
demand.
      


5 - Disconnect power to unit before disconnecting
meter. Make sure sensor wire is securely
reconnected before reconnecting power to unit.
NOTE-If the meter scale reads 0, the leads are reversed.
Disconnect power and reconnect leads for proper polarity.
B-Cooling System Service Checks
ZGB units are factory charged and require no further ad-
-

NOTE-When unit is properly charged discharge and
suction pressures should approximate those in tables 8
through 11.

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