3
d) Tube Port Restriction- Check inside the top solenoid port for object restricting
airflow to dampers.
5) AIR SIDE INTEGRITY CHECK
a) Use the Arzel “ Air Flow Indicator “ to determine if and what zones are leaking
air through tubing or damper actuators. Refer to instructions sent with the “Air
Flow Indicator”.
b) To check individual damper actuators for leakage
i) Disconnect tube from actuator and remove damper from duct
ii) Move damper blade to the closed position
iii) Hold finger over tube port.
iv) Move damper blade to the open position with finger still over port
v) The pressure build up in the actuator should impede the opening motion for as
long as you continue to push in the open direction.
vi) If the pressure subsides and the damper easily moves to the open position, the
actuator is leaking and the damper must be replaced.
vii) If the pressure holds, the damper is OK and the leak is in another damper or a
tube has come loose from a fitting.
6) LAT OPERATION
a) If furnace is cycling on internal limit or if LAT is cycling equipment Off & On
too often, check the following:
i) Oversized bypass duct depleting return air and raising discharge air
temperature. (A bypass duct is used strictly to minimize excessive static
pressure and is a detriment to heat transfer across the heat exchanger)
ii) Heating “LAT”, set point is too low; adjust to maintain supply air
temperatures within furnace manufacturers specifications.
(1) Note furnace manufacturers specified “Temperature Rise” on Equipment
Rating Label.
(2) Add 70 deg to the “maximum” temperature rise; Example- If the
specified temperature rise is “35 to 60 deg”,
Add 70 deg (typical return air
temperature) to the maximum 60 deg Rise. Your Htg LAT setting should
be 130 deg. If nuisance tripping occurs, raise the setting to eliminate
tripping without reaching the limit temperature of the furnace.
b) If Air Conditioning coil is freezing up or LAT is cycling compressor off to often,
check the following:
i) Oversized bypass duct depleting return air and lowering coil temperature.
(A bypass duct is used strictly to minimize excessive static pressure and is
a detriment to heat transfer across the coil)
ii) Set Cooling LAT set-point per the following guidelines
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