AAON RN Series, Установка, эксплуатация и обслуживание, Страница: 49 / 136

49
and one on the right side of the unit. P-traps
must be field provided and installed.
All drain connections must be used and
individually trapped to ensure a minimum
amount of condensate accumulation in the
drain pans. Use ABS type cement to join the
drain pipe connections.
Note: The drain pan connections are 1” MPT
fitting for 6-50, 60, and 70 tons (A-D Cabinet
sizes).The drain pan connections are 1.5”
MPT fitting for 55,65, 75-140 tons (E
Cabinet size).
Drainage of condensate directly onto the roof
may be acceptable in certain areas, refer to
local codes. If condensate is to drain directly
onto the roof, place a small drip pad below
the drain to protect the roof from possible
damage.
If condensate is piped into the building
drainage system, the drain pipe must
penetrate the roof external to the unit itself.
The drain line must be pitched away from the
unit at least 1/8 inch per foot. On longer runs
an air break must be used to ensure proper
drainage.
Draw-through cooling coils will have a
negative static pressure in the drain pan area.
This will cause an un-trapped drain to back
up due to air being pulled up through the
condensate drain piping.
Condensate drain trapping and piping must
conform to all applicable governing codes.
Draw-Through Coils
Figure 29 - Draw-Through Drain Trap
The X dimension on the draw-through trap
must be at least equal to the absolute value of
the negative static pressure in the drain pan
plus one inch. To calculate the static pressure
at the drain pan add the pressure drops of all
components upstream of the drain pan,
including the cooling coil, and add the return
duct static pressure. Include the dirt
allowance pressure drop for the filters to
account for the worst-case scenario.
The height from top of the bottom bend of the
trap to the bottom of the leaving pipe must be
at least equal to one half of the X dimension.
This ensures that enough water is stored in
the trap to prevent losing the drain seal during
unit startup
Note: The absolute value of the fan inlet
pressure will always be greater than or equal
to the absolute value of the static pressure in
the drain pan on draw-through units, so the
fan inlet pressure is a safe value to use for the
drain pan static pressure.
Unit must not be operated without a p-
trap. Failure to install a p-trap may
result in overflow of condensate water
into the unit.
CAUTION