Therma-Stor Products Group 300 User Manual

4

5.   Replace the cover.
Change the timer pegs back to the original pattern for use 
above 50°F.

If the low side refrigerant pressure drops to 5 PSIG, the 
low pressure control opens and shuts off the compressor 
and blower. It is an automatically reset control. Its primary 
function is to prevent damage to the compressor if a leak 
develops in the refrigeration system. It may also open if 
the unit is A) used in a cool area (below 50°F) and the 
defrost timer is not adjusted (see Sec. 2.0) or B) stored 
where it is below 40°F and then started. Under these 
conditions, the unit will restart within several minutes. 
Until the unit warms up, it may cycle several times.

The Phoenix 300 is equipped with MERV-8 pleated fabric 
air filter that must be checked regularly. Operating the unit 
with a dirty filter will reduce the dehumidifier’s capacity and 
efficiency and may cause the compressor to cycle off and 
on unnecessarily on the defrost control.
Two optional filters are available: A) a 2” pleated filter that 
has the same efficiency as the 4” standard filter, but less 
surface area. This filter would need to be changed more 
often than the 2” version. B) a 95% efficient 4” filter that 
acts as an air scrubber to catch mold and mildew spores.
The filter can generally be vacuumed clean several times 
before needing replacement. Replacement filters can be 
ordered from the factory or purchased locally if available. 
DO NOT operate the unit without the filter or with a less 
effective filter as the heat exchange coils inside the unit 
could become clogged and require disassembly to clean.

The blower motor is lubricated for life from the factory and 
does not require oiling by the owner.

There are two issues to consider when the Phoenix 300 is 
stored between uses and both pertain to the water trapped 
in the unit: damage caused by freezing and biological 
growth. The effect of the trapped water can be greatly 
reduced if precautions are taken to remove as much as 
possible before storage.
.   Use the pump purge switch (see Sec. 2.7 and Fig. 3) 

to   reduce the water level in the reservoir.

2.   Stretch the hose flat to drain it completely.

If the unit will not be exposed to freezing temperatures, 
an alternative way to reduce biological growth is to flush 
the unit with a bio-fungicide that is approved for use with 
copper, aluminum and polyethylene. To flush:
.   Run the hose to a drain.
2.   Plug in the unit but do not turn it on.
3.   Remove the air filter. Slowly pour a quart of the 

chemical through the top grille so that it drains into 
the white plastic slots.

4.   Hold in the pump purge switch to reduce the water 

level in the reservoir.

A warranty certificate has been enclosed with this unit; 
read it before any repair is initiated.
If a warranty repair is required, call the factory first at 
-800-533-7533 for warranty claim authorization and 
technical assistance.

The Phoenix 300 uses a refrigeration system similar to 
an air conditioner’s to remove heat and moisture from 
incoming air, and to add heat to the air that is discharged 
(see Fig. 2).
Hot, high pressure refrigerant gas is routed from the 
compressor to the condenser coil (see Figure 2). The 
refrigerant is cooled and condensed by giving up its heat 
to the air that is about to be discharged from the unit. 
The refrigerant liquid then passes through a filter/drier 
and capillary tubing which cause the refrigerant pressure 
and temperature to drop. It next enters the evaporator 

Figure 1: Defrost Control Timer

Above 50°F

Below 50°F