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This condition may result in the heater cycling on the high limit
thermal cutout. Open-strip heaters have an automatic reset switch
and high-limit thermal switch as a backup. Automatic reset limit
switches reset after the heater has cooled down. High-limit
thermal switches must be replaced once the circuit has been bro
-
ken.
The high-limit thermal cutout device is a safety device only, not
intended for continuous operation. This device only operates when
a problem exists; ANY condition that causes high-limit cutout
MUST be corrected immediately. High supply voltage also causes
excessive amperage draw, and may trip the circuit breaker or blow
the fuse(s) on incoming power supply.
After proper airflow and supply power are assured, regular filter
maintenance is important to provide clean air over the heater. Dirt
allowed to deposit on the heating element will cause hot spots and
eventual element burn through. These hot spots will normally not
be enough to trip the high-limit thermal cut-out device, and may
not be evident until actual heater element failure.
Cabinet/Control Box Maintenance Light
An optional Light-emitting Diode (LED) service light provides a
source of illumination in the main unit cabinet and the control box
during routine maintenance and troubleshooting in dark ceiling
spaces.
When power is turned "OFF" for maintenance or troubleshooting,
the control box/cabinet light will turn "ON" as soon as control
box/cabinet door is open (see Fig. 28).
Electrical Wiring and Controls
Refer to wiring diagram attached to unit for type and number of
controls provided on each unit.
Verify integrity of all electrical connections at least twice during
the first year of operation. Subsequently, all controls must be in
-
spected periodically for proper operation. Some components may
experience erratic operation or failure due to age. Wall thermostats
may also become clogged with dust and lint, and must be periodi
-
cally inspected and cleaned to provide reliable operation.
When replacing any components such as fuses or relays, use only
the exact type, size and voltage component as furnished from the
factory. Any deviation without factory-authorization could result
in personnel injury or damage to the unit. This will also void all
factory warranties. Only factory supplied replacement parts ensure
that the warranty and agency status remain in effect. All repair
work shall be done in such a manner as to maintain the equipment
in compliance with governing codes, ordinances and testing agen
-
cy listings.
Drain
Inspect drain before initial start-up, and prior to each cooling sea
-
son to assure that drain trap and line are clear. When clogged, clear
the debris so condensate easily flows.
Periodically inspect drain during cooling season to maintain a
free-flowing condensate. Units are provided with a secondary or
“tell-tale” drain connection that will indicate a clogged main-drain
line by flow from “tell-tale” connection.
Should algae and/or bacteria growth become a concern, con
-
sult an air conditioning and refrigeration supply organization
familiar with local conditions for chemicals, or other solu
-
tions available to control these agents.
Filters — Throwaway
Throwaway type filters; commonly used on fan coil units must be
replaced on a regular basis. The time between replacement should
be established based on regular inspection of filter, and also
recorded in the log for each unit. Refer to Table 4 for appropriate
filter dimensions compatible with each unit size. If replacement
filters are not purchased from factory, filters used should be the
same type and size as factory, or recommended by factory. Ex
-
tended surface filters must not be used due to high air pressure
drops encountered with these types of filters being incompatible
with the type of fan coil unit covered in this manual. Consult fac
-
tory for applications using filter types other than factory standard
or optional product.
Filters — Replacement and Installation
Each unit is equipped with return air filters. Filters must be period
-
ically replaced.
The units' filters are 1 in., 2 in., or 4 in. thick. Filters can be easily
accessed from the side or bottom (42DH - horizontal unit) or side
and top (42DV - vertical unit) of the filter rack (see Fig. 31 or 32).
To remove filters from the side of the filter rack:
1. Remove the side access panel (A) of the filter rack by pulling
tab at the bottom (42DH)/top (42DV) of the panel to free
from magnets, and lower (42DH)/lift (42DV) it out of the slot
(B) in the top (42DH)/bottom (42DV) of the filter frame.
2. Pull out dirty filters.
3. Replace with new appropriate size filters.
4. To re-install side access panel into filter rack:
a. Insert the tab of panel into the slot in filter frame's top
(42DH)/bottom (42DV) (B).
b. Rotate panel toward the frame, ensure magnets are
engaged.
To remove filters from the bottom of the filter rack (42DH):
1. Open hinged bottom access panel (C) - pull down to
disengage magnets.
2. Pull out dirty filters.
3. Replace with new appropriate size filters.
4. Secure bottom access panels, make sure magnets are re-
engaged.
To remove filters from the top of the filter rack (42DV):
1. Open hinged top access panel (C) - pull up to disengage mag
-
nets.
2. Pull out dirty filters.
3. Replace with new appropriate size filters.
4. Secure top access panels, make sure magnets are re-engaged.
The 42DH/DV units are designed to accept various filter sizes de
-
pending on job requirements. Each filter frame is equipped with
filter support angle brackets (D) and 1 in. or 2 in. filter slots on all
four sides of filter frame. The filter support angle brackets (D) are
designed to provide guidance and support to the new filter as it is
being inserted.
In order to accommodate 1 in. and 2 in. filters, the bracket should
be inserted into corresponding slots on all sides of the filter frame
(see Fig. 31 or 32) and secured with screws. When 4 in. filter is
installed, the brackets should be stored for future use with different
filter thickness, or discarded if 4 in. filter will be always used.
