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UHD STANDARD DUCT FURNACE INSTALLATION OPERATION AND SERVICE MANUAL
36
14.6 Pressure Switch
Pull off 3 way connector. Spring open plastic clips of mounting cradle. Replace with correct type of
pressure switch for model. The pressure switches are color coded for each pressure setting.
Carry out a start-up after working on or changing a pressure switch. See Page 21, Section 10.
14.7 Ignition Control
The control mounts to the electrical plate. Pull out ignition cable and wiring from board, noting their
positions. Release the four mounting standoffs. Refit in reverse. Ensure correct location of ignition cable
and all other wiring.
14.8 Limit Switches
14.8.1 Removal and Replacement
1. Remove the electrical connections to the switch.
2. Unscrew the two screws securing the switch.
3. Fit a new switch with two screws.
4. Reconnect the electrical connections and test operation.
MODEL
UHD[X][S][R]
150 - 175
UHD[X][S][R]
200 - 225
UHD[X][S][R]
250
UHD[X][S][R]
300 - 350
UHD[X][S][R]
400
Pressure Switch
Kit P/N
90439802 90439808 90439803 90439807 90439808
Color Code yellow orange gray brown orange
Set Point (in wc) .32 .79 .41 .68 .79
Pressure Switch
Snap Ring P/N 90439850 90439850 90439850 90439850 90439850