Greenheck Fan HRE-20 - Manual (Page 8)

Auto Drain and Fill with Freeze Protection
This system will automatically drain the sump tank and fill it with fresh water at the field adjustable intervals,
typically once every 24 hours. This flushes mineral build-up and debris from the tank to promote low
maintenance and increase media pad life. In addition, the system will protect the evaporative cooler from
freezing by draining the sump tank and supply line when the outside temperatures fall below the set point of the
outside air sensor. Typically, this is set at 45º to 50º F. The auto drain and fill control box should be installed in
an area that is shaded from direct sunlight so the outside air sensor probe will detect an accurate air
temperature.
Plumbing (see FIGURE 9)
1. Run water supply line to the unit and install Water Supply Solenoid Valve (A) in this line as close to the water
source as possible.
2. Install Drain Solenoid Valve (B) in the supply line as indicated below. From the outlet on the drain valve, run line
to a suitable drain location.
3. Run an unobstructed drain line from the sump overflow to the drain as shown below.
4. Install Sump Drain Solenoid Valve (C) in the drain line from the sump as indicated below. From the outlet on
this drain valve, run a line to a suitable drain location.
Note: Water Supply Solenoid Valve
(A) is not the same as the
Drain Solenoid valves (B) and
(C). Make sure to use the
proper valve for each location.
Check your local code
requirements for proper
installation of this type of
system. Additional drain and
supply plumbing may be
needed to meet your local
code.
Caution: All solenoid valves A, B,
and C must be installed below the
roof to protect the supply water line
from freezing. If these valves cannot
be installed below the roof, an
alternate method must be used to
protect these lines from freezing.
WATER CONTROL OPTIONS FOR EVAPORATIVE COOLING
8
Sump Drain Pipe
Sump Overflow Pipe
Side of HRE Unit
Roof Curb
Roof Line
Drain
Line
Trap
Evaporative
Cooling
Media
Water Supply
Solenoid Valve (A)
Supply Line
Sump
Drain
Solenoid
Valve (B)
Sump Drain
Solenoid
Valve (C)