23
CONTROL INSTALLATION
Controls may be installed in the unit before or after the unit is
hung or placed in the ceiling grid. However, if warm-up
switches or changeover valves are used, the controls should
be installed before the unit is placed in the ceiling structure.
Refer to Table 3 for control packages and accessory
identification.
Constant Volume Applications
1. Remove the plugs from the high-pressure and low-pres-
sure ports located at the control block of the unit.
2. Remove cap from bellows fitting (see Fig. 30) and install
11
∕
16
-in. piece of
1
∕
4
-in. OD pneumatic tubing onto the
bellows fitting (push on full length of fitting).
3. Push the diffuser baffle into the space between side dif-
fusers and down onto the center diffuser at the end away
from the unit. Then push down the end close to the unit.
The baffle will form around the legs of the diffuser
spacer and lock onto the center diffuser. See Fig. 31.
4. To prepare the control filter for installation, be sure that
the bellows chamber filter plug is pushed tightly into the
correct connection. Figure 32 shows the connection ports
on both sides of the filter. The lower bellows port on the
unit side and the small slave bellows pressure connection
on the control side should be capped or plugged before
installation. Moisten the 2 O-rings with water, then push
the filter into the unit end block until the standoffs rest on
or close to the unit end plate. See Fig. 33.
5. Remove cap from thermostat port of volume controller.
See Fig. 34. Pull shim down until released from thermo-
stat port and then pull shim out from volume controller
body. See Fig. 35. Discard shim. Re-install cap on the
thermostat port.
6. To complete installation, moisten the O-rings of the vol-
ume controller with water and push the volume control-
ler directly into the control filter. See Fig. 36 and 37.
NOTE: The thermostat port of the volume controller must be
capped.
7. If more than one unit is being controlled by a single vol-
ume controller, attach interconnecting tubing as follows
(refer to Fig. 28, page 17):
a. Use
1
∕
4
-in. OD FR tubing. Connect tubing to the unit
bellows connection on the end of the master unit
opposite the control end. Do not connect tubing to
filter bellows connection.
b. Using T-tap arrangement, connect the tubing from
the master unit to the 2 slave units on each side of
the master unit.
c. Attach interconnecting tubing from these 2 slave
units to other slave units in the air series.
Fig. 30 — Typical 37HS Air Terminal
Before Installation of Controls
Fig. 31 — Diffuser Baffle Assembly
Fig. 32 — Filter/Manifold Connections
BELLOWS
FITTING
FOR
DIFFUSER
THERMOSTAT
ASPIRATOR
HIGH
LOW
