7. Evacuate the system with a good vacuum pump and accurate
vacuum gauge. Leave the pump on the system for at least an
hour.
8. Operate the system for a short period of time, monitoring the
suction pressure to determine that the suction filter is not
becoming plugged. Replace the suction filter/drier if pressure
drop occurs. If a severe running burn out has occurred,
several filter/driers may have to be replaced to remove all of
the acid and moisture.
NOTE: NEVER use the compressor to evacuate the system or
any part of it.
7.6C Replacing a Compressor, Nonburn Out
Remove the refrigerant from the system. Replace the compressor
and liquid line filter/drier. Charge the system to 50 PSIG and check
for leaks. Remove the charge and weigh in the refrigerant quantity
listed on the nameplate. Operate the system to verify performance.
7.7 Remote Controls
The Ultra-Aire XT150H is controlled by devices mounted on a panel
that is remote from the unit. You may or may not have the devices
listed below depending on the model of the remote control panel
you purchased. If the Ultra-Aire XT150H fails to operate as desired,
always check the settings of the controls to insure that they are
correct. Check that the controls are receiving 24Vac from the
Ultra-Aire XT150H. Check the connections between the Ultra-Aire
XT150H, the control panel, and the field control wiring.
7.7A Humidity Control
The humidity control is an adjustable switch that closes when the
relative humidity of the air in which it is located rises to the dial set
point. It opens when the RH drops 4 to 6% below the set point. If
the Ultra-Aire XT150H does not run, try turning the humidity control
clockwise until it reaches the stop and the knob pointer points at
“Max Dry” (see back of control panel cover). If it still does not run,
remove the stop screw from the panel and turn the knob farther. If
it then runs, the humidity control is out of calibration or the RH is
below 40%.
The Ultra-Aire XT150H is equipped with an automatic defrost
mechanism. If the Ultra-Aire XT150H operates in conditions that
develop frost on the evaporator, it will sense the frost build-up and
automatically defrost the evaporator. The Ultra-Aire XT150H may
not appear to be operating correctly during the defrost sequence,
but once the defrost sequence is completed, the Ultra-Aire XT150H
will resume dehumidifying.
7.7B Programmable Ventilation Timer
The ventilation timer controls the impeller fan and the motorized
fresh air damper. When the ventilation timer is activated, the
Ultra-Aire XT150H will circulate the indoor air, and bring in fresh air
from outside. The ventilation timer should be set for the required
ventilation of the residence. The home should be ventilated with
fresh air as suggested by applicable codes and standards.
If the Ultra-Aire XT150H fails to ventilate as expected, check that
the time on the timer is correct. For the timer to carry out the
program schedule, the slide switch in the upper left corner on the
timer must be set to “AUTO”. The slide switch in the upper right
corner of the Ultra-Aire XT150H must be set to “RUN”. Also check
the programs on the timer to be sure that the timer is calling for
ventilation at the correct times. If the timer fails to operate or
operates erratically, reset the timer; see section 4.5 of this manual.
7.8 Defrost Thermostat
The defrost thermostat is attached to the refrigerant suction tube
between the accumulator and the compressor. It will automatically
shut the compressor off if the low side refrigerant temperature
drops due to excessive frost formation on the evaporator coil. The
impeller fan will continue to run, causing air to flow through the
evaporator coil and melt the ice. When the ice has melted, the
evaporator temperature will rise and the thermostat will restart the
compressor.
7.9 Electric Ventilation Damper
The electric ventilation damper is controlled by the ventilation timer.
The damper will open when the ventilation timer is activated to allow
fresh air into the structure through the 6” diameter fresh air inlet duct.
The electric ventilation damper will remain closed when the ventilation
timer is not activated to prevent over-ventilating the structure when
the unit is dehumidifying or recirculating the indoor air.
The electric ventilation timer operates on 24 Vac from the control
circuit. DO NOT connect high voltage to the damper motor or
damage to the motor may result. DO NOT force the blade of the
damper by hand or damage to the damper motor may result.
The damper opens in one direction only. The damper rotates very
slowly, allow sufficient time for the damper to cycle. The damper
will take approximately 1 minute to cycle from closed to open or
from open to closed.
If the electric ventilation damper fails to operate:
1. Check that the wiring is correct and that voltage is present at
the damper motor.
2. Check for any obstruction inside the damper. If the electric
ventilation damper fails to operate after performing these
checks, it must be replaced.
7.10 Condensate Pump Kit
An optional condensate pump kit is available from the factory
for use with the Ultra-Aire XT150H. Condensate is automatically
pumped to a remote location when the water level in the pump's
reservoir rises to close the float switch.
FOR HVAC INSTALLER ONLY
15
Ultra-Aire XT150H Installer’s & Owner’s Manual
