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Checking The Burner Velocity Pressure
PS-10 & PS-11 air switches are factory calibrated.
Do not adjust.
Check the velocity pressure by disconnecting both
pressure sensing tubes from one of the high air
fl
ow
switch. Connect one end of your manometer to each
sensing tube and start the fan. The permissible
pressure range should be marked on the switches.
If it’s close to the high or low trip points of the air
fl
ow
switches, you could have a problem: High pressure
switch open means too much velocity; low pressure
switch open means not enough velocity.
Jumper the switch from which you’ve disconnected the
sensing tubes and get the burner running in high
fi
re.
Your differential pressure should have dropped. If it is
near the low switch trip point you need more air.
Some adjustments can be made by repositioning the
burner pro
fi
le plates. If the high switch is open, you
can open the pro
fi
le plates. If the low switch is open
you can close the pro
fi
le plates. Remember to keep
the distance between the burner and pro
fi
le plates
the same opening on both the top and bottom of the
burner when making these adjustments.
Depending on the motor amps you may want to
change the speed of the fan if the unit has adjustable
sheaves.
Don’t forget to remove the jumper and reconnect the
sensing tubes to the switch.
Call factory with any questions.
Pro
fi
le
Plates
TROUBLESHOOTING GUIDE