Parameter Generation and Control 9354-4250, Installation And Operation Manual, Page: 29 / 90

PGC, Inc 500-1000 CFM Air Handler May 2006
Appendix A A-13
ii. Is ice present on the fins of the evaporator (or on the surface of the
submerged tube evaporator)? It is not unusual for the supply lines to the
finned evaporator to be covered in ice; however, it is important that no
ice form on the surface of the coil. Ice on the surface of the coil could
indicate poor water flow or a low refrigerant charge.
iii. Is the refrigeration discharge pressure too high?
1. The air-cooled condenser could be dirty
2. The ambient temperature could be above 95°F
3. The condenser fan(s) may not be working
c. Does the heat load in the chamber exceed the capacity of the system? Since the
heat from the air stream is removed by the evaporator and the water spray, if the
heat load in the chamber is too great, the refrigeration system will become
overloaded if the heat load in the chamber is too great. The first indication of this
will be water temperature, and therefore Rh, that is higher than requested.
A
IR
T
EMPERATURE
1.) The refrigeration system must have enough capacity to control the water temperature.
If the water temperature is out of control, it is usually not possible to control the air
temperature.
2.) Is the air damper operating properly? Press the clutch release on each actuator two
times to initialize the motor. Observe that the damper moves full travel in both
directions; this may take up to three minutes to complete. If the motor cannot reach
the stops (the Phillips screws at each end of rotation), determine cause of the fault.
3.) Are the air heaters operating properly? Measure the air heater current when the
SmartPad™ indicates 100% air heat output.
4.) Is the airflow restricted or the ductwork leaking? Ordinary A/C ductwork is not
sufficiently vapor tight for an environmental chamber. The duct work must be
capable of holding water for proper vapor barrier.
5.) Is the blower operating efficiently? Inspect the blower wheel for sediment that can
accumulate over time, which decreases the efficiency of the wheel. If this build-up
cannot be removed safely, the wheel must be replaced.
6.) Is the chamber properly sealed?
a.
Check the seals around any doors and windows.
b. Are all covers properly installed?
7.) Has the load in the chamber increased?
8.) Check the line voltage. Low line voltage will drastically reduce the wattage of the air
heaters and efficiency of the compressor.
W
ATER
L
EVEL
1.) The overflow drain must be connected to an open drain; the drain will not work
properly if any backpressure is present.
2.) The overflow drain must functional. If the water level is above the overflow drain
standpipe, the drain is not working properly and the refrigeration system may become
overloaded.
3.) The float valve must maintain the proper water level. The proper water level is high
enough to prevent the pump from cavitating (drawing air into the pump inlet), but
should not be high enough to cause excessive, constant overflow (too much overflow
will overload the refrigeration system)