Reznor MAPS II Unit Installation Manual - Manual (Page 19)

Form I-MAPS II, P/N 206131 (Rev 13), Page 19
6.2 Condensate
Drain
A slide-out, removable drain pan with a 1" male NPT drain connection is located
below the coil cabinet (See FIGURE 2A or FIGURE 2B, page 7 or 8). When
connecting the drain line, provide a means of disconnecting the line at or near
the cabinet connection to allow the drain pan to be removed for cleaning.
Ensure the system is level and install a trap in the drain (see
FIGURE 9A).
Pitch the drain line at least 1/2" (13mm) for every 10 feet (3M) of horizontal run.
Drain lines must not interfere with drain pan or access panels. An obstruction
in the drain or a poorly designed drain can cause condensate pan to over flow.
Overflow could result in unit or building damage.
If the installation or local code requires, run drain into a waste water system.
Condensate Drain
Trap
The design of the drain trap is important. Since the condensate drain pan is
on the blower inlet side, there is a negative pressure at the drain relative to
the ambient. The trap height must account for this static pressure difference.
Maximum negative static can be determined by reading the negative pressure
at the blower inlet and adding .2” w.c. to allow for dirty filters.
If dimension "B" in
FIGURE 9A is not tall enough, the water seal will not hold,
and air will be drawn through the drain pipe into the system. If the outlet leg of
the trap is too tall, water will back up into the drain pan. As condensate forms
during normal operation, the water level in the trap rises until there is a con-
stant outflow. FIGURE 9A illustrates the appropriate dimensions for trapping a
negative pressure system.
��������������
�������������
������������
�������������
����������
����
FIGURE 9B -
Drain
Trap with
Cleanout
�
�
���
�
�
�
�
�
�
����
����������
����������
A = 1" (25mm) for each 1"
(25mm) of maximum static
pressure plus 1" (25mm)
B = A + A/2
FIGURE 9A -
Condensate
Drain Trap
Dimensions
Improper trap design accounts for some condensate drainage system failures,
but incorrect use and maintenance of condensate drain traps can also cause
problems. The combination of airborne particles and moisture in the air han-
dler can result in algae formation in the drain pan and traps. The traps must be
cleaned regularly to avoid blockage that can slow or stop water flow, resulting
in backup into the system.
If drains have a cleanout opening ( FIGURE 9B), be sure to close the opening
after cleaning.
Condensate Drain
Use
Seasonal Usage - At the beginning of the cooling season, inspect and clean
the entire cooling coil cabinet including the condensate drain pan. Thoroughly
clean dirt, algae, grease, and other contaminates. Inspect condensate drain
pans, traps, and piping; fill traps with water to ensure proper operation. During
a wintertime shutdown of the cooling system it may be desirable to disconnect
and remove all water from the traps and drains to prevent freeze damage. If
local building codes permit, traps may be filled with an antifreeze solution. Or,
piping may be designed with freeze plugs or other freeze protection methods
(such as a heat tape).
Year Round Usage - Climates or applications with cooling requirements year
round require more frequent inspections of the cooling coil cabinet and conden-
sate drains. Depending on climate, freeze protection of traps may be required
during non-cooling hours.