Water Bypass Loop; Bleed Air From Water Lines - Lennox SW 036 Installation Instructions Manual

Water Bypass Loop

The water bypass loop is used to flush the water system
without routing water through the rooftop unit
components. Units are shipped with three-way water
in/out valves in the bypass position. Refer to figure 9 for
water flow path. This prevents dirt and debris buildup in
the strainers and other components. Before placing unit
in service, bleed air from water lines (next section).
IMPORTANT - Make sure the three-way valves are
completely open (see figure 10). If the valves are not
fully open the amount of water entering the
water-to-refrigerant coil may be reduced. Reduced
water supply to the coil could severely limit unit
cooling performance. Reduced water flow could also
cause the water to freeze. Coils damaged due to
freezing water are not covered under warranty.
036, 060, 120 UNITS
Position Of Lever
On Inlet Valve
036, 060, 120 UNITS
Water Routed
To Coil
Position Of Lever
On Inlet Valve
WATER ROUTING DURING BYPASS MODE
Position Of Lever
On Outlet Valve
Water
Routed To
Bypass Loop
WATER WATER
IN OUT
WATER ROUTING DURING NORMAL OPERATION
Position Of Lever
On Outlet Valve
WATER WATER
IN OUT

Bleed Air From Water Lines

1- Turn off all power to unit before bleeding lines.
2- Turn the three-way water inlet valve to main loop
position. If running water is not heard circulating,
make sure the main system pump is running.
3- Slowly open the manual air vent bleed port(s). When
the venting stops, close the air vent and turn the
three-way water outlet valve to main loop position.
The water will now be routed as shown in figure 10.
4- Measure the differential pressure across the
automatic flow regulator using a PT gauge set. See
figure 11. A minimum differential of 2.0 PSI is
required for proper flow.
Position Of Lever
FIGURE 9
Water Routed
Position Of Lever
On Inlet Valve
FIGURE 10
Page 11
240 UNITS
Position Of Lever
On Outlet Valve
Water
Routed To
Bypass Loop
On Inlet Valve
WATER
IN
240 UNITS
Position Of Lever
On Outlet Valve
To Coil
WATER
IN
WATER
OUT
WATER
OUT