Installation manual

Page 24 IM-487
Building Pressurization Applications
1. Install a "T" fitting with a leak-tight removable cap in each
tube near the sensor. This will facilitate connecting a
manometer or pressure gauge if testing is required.
2. Locate the building pressure (HI) tap in the area that re
quires the closest control. Typically, this is a ground level
floor that has doors to the outside.
3. Locate the building tap so that it is not influenced by any
source of moving air (velocity pressure). These sources
may include air diffusers or outside doors.
4. Route the building tap tube between the curb and the sup-
ply duct, and feed it into the unit through the knockout in
the bottom of the control panel (see Figure 24 on page 23).
Connect the tube to the V4 inch HI fitting on sensor SPS2.
The sensor must not support the weight of the tubing; use
tube clamps or some other means.
5. Locate the reference pressure (LO) tap on the roof. Keep
it away from the condenser fans, walls, or anything else
that may cause air turbulence. Mount it high enough
above the roof so that it is not affected by snow. If the
reference tap is not connected to the sensor, unsatisfac-
tory operation will result.
6. Use an outdoor static pressure tip (Dwyer A306 or equiva-
lent) to minimize the adverse effects of wind. Place some
type of screen over the sensor to keep out insects. Loosely
packed cotton works well.
7. Route the outdoor tap tube out of the main control panel
through a small field-cut opening in the edge of the control
wiring raceway cover (see Figure 24 on page 23). Cut this
"mouse hole" in the vertical portion of the edge. Seal the
penetration to prevent water from entering. Connect the
tube to the 1/4 inch LO fitting on sensor SPS2.
Lab Pressurization Applications
1. Install a ”T” fitting with a leak-tight removable cap in each
tube near the sensor. This will facilitate connecting a
manometer or pressure gauge if testing is required.
2. Use different colored tubing for the controlled space pres-
sure (HI) and reference pressure (LO) taps, or tag the tubes.
3. Regardless of whether the controlled space is positive or
negative with respect to its reference, locate the HI pres-
sure tap in the controlled space. (The setpoint can be set
between -0.2 and 0.2" W.C.)
4. Locate the reference pressure (LO) tap in the area surround-
ing the controlled space. If the reference tap is not connected
to the sensor, unsatisfactory operation will result.
5. Locate both taps so that they are not influenced by any
source of moving air (velocity pressure). These sources
may include air diffusers or doors between the high and
low pressure areas.
6. Route the tap tubes between the curb and the supply duct,
and feed them into the unit through the knockout in the
bottom of the control panel (see Figure 24 on page 23).
7. Connect the tubes to the appropriate ¼ inch fittings on sen-
sor SPS2. The sensor must not support the weight of the tub-
ing; use tube clamps or some other means.
Condensate Drain Connection
The unit is provided with a 1.5" male NPT condensate drain
connection. Refer to certified drawings for the exact location.
The unit and drain pan must be level side to side and a P-trap
must be installed for proper drainage.
Units may have positive or negative pressure sections. It is
recommended that traps be used in both cases with care given
to negative pressure sections. In Figure 26 on page 25,
dimension "A" should be a minimum of 8" (203 mm). As a
conservative measure to prevent the cabinet static pressure
from blowing or drawing the water out of the trap and causing
air leakage, dimension "A" should be two times the maximum
static pressure encountered in the coil section in inches w.c.
Drainage of condensate directly onto the roof may be accept-
able; refer to local codes. It is recommended that a small drip
pad of either stone, mortar, wood or metal be provided to pro-
tect the roof against possible damage.
If condensate is to be piped into the building drainage system,
pitch the drain line away from the unit at a minimum of 1/8"
per foot. The drain line must penetrate the roof external to the
unit. Refer to local codes for additional requirements. Sealed
drain lines require venting to provide proper condensate flow.
Where the cooling coils have intermediate condensate pans on
the face of the evaporator coil, copper tubes near both ends of
the coil provide drainage to the main drain pan. Check that
the copper tubes are in place and open before the unit is put
into operation.
On units with staggered cooling coils, the upper drain pan
drains into the lower coil drain pan through a copper tube
near the center of the drain pan. Check that this tube is
open before putting the unit into operation and as part of
routine maintenance.
Because drain pans in any air conditioning unit will have
some moisture in them, algae, etc. will grow. Periodic clean-
ing is necessary to prevent this buildup from plugging the
drain and causing the drain pan to overflow. Keep the drain
pans clean to prevent the spread of disease. Cleaning should
be performed by qualified personnel.
WARNING
Clean drain pans regularly. Growth in uncleaned drain
pans can cause disease.
Cleaning must be done by trained and
experienced personnel.