035-14520-001 Rev. B (0803)
Unitary Products Group
19
DRAIN CONNECTIONS
All drain lines should be trapped a minimum of three inches,
should be pitched away from unit drain pan and should be no
smaller than the coil drain connection.
Route the drain line so that it does not interfere with accessi-
bility to the coil, air handling system or filter and will not be
exposed to freezing temperatures. See Figures 2, 3 and 4.
NOTE:
When the coil is installed in an attic or above a fin-
ished ceiling, an auxiliary drain pan should be provided under
the coil as is specified by most local building codes.
Coils should be installed level or pitched slightly toward the
drain end. Suggested pitch should not exceed 1/4 inch per
foot of coil.
The coil is provided with a secondary drain that should be
trapped and piped to a location that will give the occupant a
visual warning that the primary drain is clogged. If the sec-
ondary drain is not used it must be capped.
The drain pan connections are designed to ASTM Standard D
2466 Schedule 40. Use 3/4" PVC or steel threaded pipe.
Since the drains are not subject to any pressure it is not nec-
essary to use Schedule 40 pipe for drain lines.
It is recommended that all drain connections be sealed with
teflon tape or equivalent.
MAINTENANCE
Filters must be cleaned or replaced when they become dirty.
Inspect at least once per month. The frequency of cleaning
depends upon the hours of operation and the local atmo-
spheric conditions. Clean filters keep unit efficiency high.
COIL CLEANING
If the coil needs to be cleaned or replaced, it should be
washed with Calgon coilclean (mix one part Coilclean to
seven parts water). Allow solution to remain on coil for 30
minutes before rinsing with clean water. Solution should not
be permitted to come in contact with painted surfaces.
LUBRICATION
The bearings of the blower motor are permanently lubricated.
CONDENSATE DRAINS
During the cooling season check the condensate drain lines
to be sure that condensate is flowing from the primary drain
but not from the secondary drain. If condensate ever flows
from the secondary drain the unit should be promptly shut off
and the condensate pan and drains cleaned to insure a free
flowing primary drain.
TROUBLESHOOTING GUIDE
Threaded drain connection should be hand-tight-
ened, plus no more than 1/16 turn.
Horizontal drain cutout in the center access panel
should be removed by using a utility knife. DO NOT
TRY TO KNOCK OUT.
PROBLEM
POSSIBLE CAUSE
Blower Runs all of the time
1. No heat units do not have 6-pin connector installed.
2. Limit open or not connected.
3. Variable speed break-out tab broken out.
4. Blower OFF delay (approx. 1 min).
5. Thermostat fan switch in “ON” position.
Blown Fuse
1. Low voltage short to C or ground from R, Y, G, W, or O.
No 24V
1. 4-pin connector loose.
2. Loose wire from control to transformer (24V and 230V).
3. Blown fuse on control board.
No 2nd stage heat
1. Check 6-pin connector and connections to panel mount relays.
2. Verify that both W
1
& W
2
are connected at the terminal strip.
No Heat or Limited Heating
1. Check filter.
2. Closed registers.
3. Restricted airflow (supply registers or return registers)
4. Check blower motor operation.
5. If the safety limit opens 4 times, the control will not permit the heating element to operate for 1 hour.
