PART #461248
READ AND SAVE THESE INSTRUCTIONS
HEAT RECOVERY UNIT
WITH EVAPORATIVE COOLING
®
Models:
HRE-20, 45, 55, & 90
INSTALLATION, OPERATION AND MAINTENANCE MANUAL
**WARNING**
DISCONNECT AND SECURE TO THE "OFF" POSITION ALL ELECTRICAL POWER TO THE UNITS
PRIOR TO INSPECTION OR SERVICING. FAILURE TO COMPLY WITH THIS SAFETY PRECAUTION
COULD RESULT IN SERIOUS INJURY OR DEATH.
**IMPORTANT**
ALL FACTORY PROVIDED LIFTING LUGS MUST BE USED WHEN LIFTING THE UNITS. FAILURE TO
COMPLY WITH THIS SAFETY PRECAUTION COULD RESULT IN PROPERTY DAMAGE, SERIOUS
INJURY OR DEATH.
Indirect Evaporative Cooler
(Exhaust/Scavenger Airstream)
Direct Evaporative Cooler
(Outdoor/Supply Airstream)
INSTALLATION
The system design and installation should follow
accepted industry practice, such as described in the
ASHRAE Handbook.
Adequate space should be left around the unit for
piping coils and drains, filter replacement, and
maintenance. Sufficient space should be provided on
the side of the unit for routine service and component
removal should that become necessary.
Lift using lifting
lugs and
See pages 6 and 7 for more detail on appropriate
clearances.
spreader bar
LIFTING
Units must be lifted as it ships from the factory. All
units are equipped with lifting lugs. THE USE OF ALL
LIFTING LUGS IS MANDATORY WHEN LIFTING.
Lifting should only be done with all access doors
closed to avoid damaging the unit. To prevent
damage to the unit cabinetry, use spreader bars.
Spreader bars must be in position to stop cables from
rubbing the frame or panels. Before hoisting into
position, test lift to insure stability and balance. Avoid
twisting or uneven lifting of the unit. Never lift units by
weatherhoods.
FIGURE 1
UNIT WEIGHTS (dry weights)
Unit Size Approx. Weight (lbs)
HRE-20
HRE-45
HRE-55
HRE-90
1500
2300
3000
5000
V
RECOMMENDED ROOF OPENING
Model
U
V
EXHAUST
INLET
HRE-20
HRE-45
HRE-55
HRE-90
46
54
65
85
37
39
47
49
U
SUPPLY
OUTLET
All dimensions shown are in inches.
FIGURE 2
3
ROOF CURB MOUNTING
1. Factory Supplied Roof Curbs
Roof curbs are Model GKD, which are shipped in a
knockdown kit and require field assembly (by
others). Assembly instructions are included with
the curb.
2. Cut Roof Opening and Locate Curb
Layout the unit roof opening such that the supply
discharge & exhaust inlet of the unit will line up
with the corresponding ductwork (refer to
Recommended Roof Openings on page 3). Be
sure to allow for the recommended service
clearances. Keep the supply inlet of the unit away
from any other exhaust fans.
3. Install Curb
Locate curb over roof opening and fasten in place.
Check that the diagonal dimensions are within
1/8 inch of each other and adjust as necessary.
Shim as required to level. Lower unit onto curb by
following the LIFTING instructions on page 3 of
this manual. Note,
roof curbs fit inside
the unit base.
Curb Outside Dimensions
Model
L
W
4. Install Duct Work
Installation of all
HRE-20
HRE-45
HRE-55
HRE-90
93
51
L
100.5
112.75
60.63
71.5
W
ducts should be
done in accordance
with SMACNA and
AMCA guidelines.
125.75 90.75
FIGURE 3
All dimensions shown are in inches.
DUCT WORK CONNECTIONS
Examples of good and poor fan-to-duct connections are shown below (See FIGURE 4). Airflow out of the fan
should be directed straight or curve the same direction as the fan wheel rotates. Poor duct installation will result
in low airflow and other system effects.
n
o
i
t
n
o
i
t
Length of Straight Duct
a
t
a
t
o
o
R
R
GOOD
POOR
FIGURE 4
SUPPLY WEATHERHOOD
Supply weatherhood will be factory mounted.
EXHAUST WEATHERHOOD
The exhaust weatherhood is shipped separately as a kit with its own instructions.
EXHAUST DAMPERS
Backdraft dampers for exhaust discharge are mounted in the unit. Motorized dampers are shipped loose (inside
HRE) and must be field installed.
4
INSTALLATION (continued)
ELECTRICAL CONNECTIONS
The electrical supply must be compatible with that shown on the nameplate: voltage, phase, and amperage
capacity. The electrical supply line must be properly fused and conform to local and national electrical codes.
All internal electrical components are pre-wired at the factory. Field electrical connections only need to be made
inside the unit to the main disconnect (See FIGURE 5, Item #1) and the 24 volt control circuit (See FIGURE 5,
Item #7). A door interlocking safety disconnect is provided as standard feature.
Note: Standard factory installed electric post heaters have their own disconnect separate from the unit
disconnect. Thus, electric post heaters require a separate power connection.
IMPORTANT:
Use minimum 14 ga. wire for 24 volt control power.
Control wire resistance should not exceed 0.75 ohms (approximately 285 feet total length for
14 ga. wire; 455 feet total length for 12 ga. wire). If wire resistance exceeds 0.75 ohms, an
industrial-style, plug-in relay should be added to the unit control center and wired in place of
the remote switch (between terminal blocks 2 and 3 on the control strip — See FIGURE 5,
Item #7). The relay must be rated for at least 5 amps and have a 24 Vac coil. Failure to
comply with these guidelines may cause motor starters to “chatter” or not pull in which can
cause contactor failures and/or motor failures.
TYPICAL CONTROL CENTER COMPONENTS
1. Main Disconnect
2. Motor Starter — Exhaust/Scavenger
Air Fan
3. Motor Starter — Outdoor Air Fan
4. Motor Contactor — Energy Wheel
5. Control Power Transformer
(24 VAC Secondary)
6. Energy Wheel Motor Transformer
(230 VAC Secondary)
(for HRE-20 & HRE-45 units with
primary voltage greater than 230 Vac)
7. 24 VAC Terminal strip
1
8
5
6
8. Fuses for the control circuit, wheel
drive transformer, and blower
motors.
7
4
Control Center
O
f
f
On
3
2
Main
Disconnect
Intake
Hood
FIGURE 5
Exhaust
Hood
5
SERVICE CLEARANCES / ACCESS PANEL LOCATIONS for Model HRE
HRE-20, 45, 55, and 90 units require minimum clearances for access on all sides for routine maintenance. Filter
replacement, drain pan inspection and cleaning, energy wheel cassette inspection, fan bearing lubrication and
belt adjustment, are examples of routine maintenance that must be performed. Blower and motor assemblies,
energy recovery wheel cassette, coil and filter sections are always provided with a service door or panel for
proper component access. Clearances for component removal may be greater than the service clearances,
refer to FIGURES 6 and 7 below for these dimensions.
Clearances for service and component removal on HRE-20 and HRE-45
36 in.
Exhaust
Hood
Access Panel
Electrical Box
36 in.
Indirect
Evap
Section
0 in.
Exhaust Air
Intake
Clearance without
IG Heater
52 in.
Clearance with
IG Heater
Direct
Evap
Section
Access Panel
*48 in. **64 in.
TOP VIEW
*Clearance for energy wheel removal on HRE-20.
**Clearance for energy wheel removal on HRE-45.
FIGURE 6
Clearances for service on HRE-55 and HRE-90
42 in.
Exhaust
Hood
Access Panel
Electrical Box
42 in.
Indirect
Evap
Section
0 in.
Exhaust Air
Intake
Clearance without
IG Heater
52 in.
Clearance with
IG Heater
Direct
Evap
Section
Access Panel
42 in.
TOP VIEW
FIGURE 7
6
Evaporative Cooling Modules
Indirect Evaporative Cooler
(Exhaust/Scavenger Airstream)
It is important to mount the heat recovery unit level to
ensure proper operation and water drainage. Piping
should be of adequate size to provide sufficient
supply of water to meet the maximum demand of the
evaporative coolers.
Evap Module Start-Up
1. After the energy recovery unit is set in place, run
the overflow and drain lines to the exterior fittings
on the evaporative cooler (drain & overflow
connections at unit are 3⁄4-inch female pipe thread).
The supply line can be attached at the
downstream side of the evaporative cooler. A
manual shut off valve should be mounted in the
supply line near the unit for servicing purposes.
Also, a trap should be installed in the drain line to
prevent sewer gas from being drawn into the unit
(see Figure 8).
Direct Evaporative Cooler
(Outdoor/Supply Airstream)
2. The cooler will be prewired by the factory.
6. After the media break-in period, the water flow
rate over the media needs to be checked. The
pumps should provide enough water to saturate
the media in 1-3 minutes. If adequate flow rate is
not achieved, consult with the factory.
3. Check to make sure that the pump filter is around
the pump inlet.
4. Turn the water on and allow the pan to fill up with
water. The float should be adjusted to provide 2
inches of water depth in the sump.
7. The water bleed-off rate will now need to be
adjusted. This measurement is 3 to 6 percent of
the media flow rate. The recommended flow rate is
11⁄2 to 2 GPM per
5. Saturate the media without any airflow through the
unit. A jumper wire is required on the terminal strip
to provide power to the evaporative cooler pump
(see the wiring diagram for the proper location).
This saturation process will break-in the media and
minimize the odors associated with the media. The
media’s break-in period should be no less than 20
minutes. When the process is complete, remove
the jumper wires in the control center.
Unit Size Media Pad Top Area
square foot of
HRE-20
HRE-45
HRE-55
HRE-90
1.5 ft2
2 ft2
2.5 ft2
3.3 ft2
media pad top area
(see table at right).
After the unit has
been installed and
running for two
weeks the unit should be checked for mineral
deposits. If there are deposits, the bleed-off rate
needs to be increased. Some areas of the country
have water with greater amounts of dissolved
minerals requiring a higher bleed-off rate.
Note: Evaporative media may foam for a short
period following the initial start-up. Leave
the bleed-off valve fully open until the
foaming stops.
8. Verify that both airflow and system static pressure
are in agreement with the specifications. If these
conditions are met, check for water carry over
from the discharge side of the media. If carry over
is observed, check the distribution header for
holes or tears and the
Side of HRE Unit
Drain Line
Evaporative
Cooling
water standoff tube for
blockage.
Overflow
Media
Sump
Trap
9. After all final
Manual
Shutoff
Valve
adjustments are made,
remove the jumper
wires and replace all
Drain
Line
Roof Curb
access panels. The
unit is now ready for
operation.
Roof Line
Manual Shutoff Valve
Supply Line
FIGURE 8
7
WATER CONTROL OPTIONS FOR EVAPORATIVE COOLING
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
Side of HRE Unit
proper valve for each location.
Check your local code
Sump Drain Pipe
requirements for proper
installation of this type of
system. Additional drain and
supply plumbing may be
needed to meet your local
code.
Evaporative
Cooling
Media
Sump Overflow Pipe
Sump
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
Roof Curb
Roof Line
Sump Drain
Solenoid
Valve (C)
alternate method must be used to
protect these lines from freezing.
Water Supply
Solenoid Valve (A)
Drain
Solenoid
Valve (B)
Supply Line
Trap
Drain
Line
8
TROUBLE SHOOTING FOR EVAPORATIVE MODULE
Symptom
Solution
Insufficient water
A. Check water level in base pan. The level should be at 2 inches.
B. Check the pump filter at the inlet. Clean the filter if clogged or dirty.
C. If pump is not operating, check wiring for loose connections and proper
voltage.
volume or recirculation
pump not operating
Irregular water
distribution on cooling
media
Water distribution header, orifices or media partially blocked or plugged.
Remove evaporative cooler from unit.
Disassemble and clean distribution header, orifices and media.
A. Check water flow across the face of the media. Irregular water distribution
must be corrected (see above)
Scale and mineral
deposit formation on
face of media
B. Increase water flow rate. Media is self cleaning with flow rate of 11⁄2 to 2
gpm per square foot of media top area. Generally this flow rate prevents
dissolved solvents from collecting on the media. To prevent further trouble,
flush and clean the system more frequently.
C. If this condition persists, chemicals may need to be added. Water pH
should be maintained between 6 and 8.
A. Irregular water distribution on face of media (see above).
B. Average face velocity exceeds 650 fpm. Decrease fan rpm and airflow.
C. Localized face velocities exceeding 650 fpm. Air filters or media face area
is partially blocked. Clean or replace air filters and media.
D. Check the overflow for blockage.
Water Carry-Over
A. Irregular water distribution over face of media (see above).
B. Check for uniform air flow.
Inadequate cooling
C. Check outside wet-bulb temperature. High wet-bulb temperatures can
decrease performance.
D. Check water flow rate over media. Flow rate should be 11⁄2 to 2 gpm per
square foot of media top area.
A. Check the water bleed off rate and make sure that it is not excessive.
B. Check water level in base pan. The level should be at 2 inches.
Excessive water
discharge into drain
Pad installed backwards. To get the
performance from the cooling pads,
they must be installed properly. The
pads are manufactured with 15/45
degree flute angles. The pads must
always be installed with the steeper
flute angle sloping down toward the
entering air side. See figure on right.
Poor performance after
cooling pad
replacement
45°
Entering Air
Leaving Air
15°
9
EVAPORATIVE COOLING MAINTENANCE
Regularly scheduled maintenance is the key to peak
performance, minimized cost, and extended life of the
evaporative cooler. The following is a checklist of
Continuous operation in this manner may cause
serious damage and void the warranty.
items that need to be looked at on a regular basis.
7. At the end of each cooling season the
evaporative cooler should be thoroughly cleaned.
A dispersant and biocide (consult water
1. The media should be checked for mineral and
foreign material deposits that have built up. If
these items are left on the media, the life and
performance of the unit will be greatly reduced.
Also, there are risks of water carry over when this
type of condition exists. When signs of mineral
build-up are noticed, you should increase the
bleed off rate. If this does not solve the problem,
chemicals may need to be added to the water.
The evaporative pads tend to be self cleaning.
Depending on water quality and system
treatment consultant for suitable materials and
dosage levels) should be recirculated for 12 to 24
hours prior to performing the following steps:
a) Disconnect power to unit.
b) Shut off all water to the unit
c) Open evaporative cooling section door
d) Flush distribution headers and media for 20
minutes
e) Turn off pumps and drain all water distribution
piping, headers, etc.
maintenance, the useful life of the pads should
be 3 to 5 years.
f) Dry media completely by running blowers.
g) Brush media as described in Paragraph 2 and
perform steps d and e again.
h) Clean all remaining components (i.e. sump,
pump, etc.) of any mineral deposits or foreign
materials
2. The media should be periodically brushed lightly
with a soft bristle brush in an up and down
motion (never brush side-to-side) while flushing
with water. This will also aid in reducing the
amount of foreign material build-up.
i) Replace all worn or non-functioning parts
j) Reassemble the cooling unit.
k) Close cooling section door.
3. The water should be shut off and all the lines
drained when the temperature drops below 50°F.
l) Turn the main disconnect 'ON', leaving the
cooling switch in the 'OFF' position.
4. When the evaporative cooler is going to be used
for the first time each season, it is recommended
that the media be flushed with clean water for a
period of 2 minutes (see Evap Module Start-Up
on page 7).
8. If the evaporative cooler will be turned off during
the cooling season for an extended period of
time, it is recommended that the media be dried
out. This can be accomplished by allowing the
blowers to continue to run for 1-2 hours. Doing
so, will prevent organic build-up on the media
and subsequent odors getting into the space.
5. At the beginning of each cooling season, the
upright recirculating pump should have the shaft
oiled and spun to eliminate the potential of
seizing and pump burn out.
9. Media should be permitted to dry once per week
by allowing the blowers to run for 1-2 hours.
6. If the cooling media was removed from the unit,
check to make sure that is not installed
backwards. If the media is installed backwards,
there will be large amounts of water carry over
downstream of the evaporative cooler.
10. A flush cycle should be performed weekly for one
hour with the fans off.
10
WATER COIL APPLICATION
RECOMMENDATIONS
Factory installed heating components are
mounted down stream of the energy wheel (and
direct evaporative cooler if supplied) on the
supply air side of the unit.
See FIGURE 10 for coil connection location. Coil
connections are located external to the unit as
shown. Coil connections that are not external
have been ordered from the factory with interior
or exhaust air stream coil connections.
Water coil
connections
FIGURE 10
1. Piping should be in accordance with accepted
industry standards. Pipework should be supported
independently of the coils. Water connections are
male NPT iron pipe. When installing couplings, do
not apply undue stress to the connection
extending through the unit. Use a backup pipe
wrench to avoid breaking the weld between coil
connection and header.
release all of the air from the coil. To maintain heat
transfer capacity, periodically vent any air in coil.
4. Water coils are not normally recommended for use
with entering air temperatures below 40oF;
however, the energy recovery wheel maintains a
pre-coil temperature higher than 40oF. No control
system can be depended on to be 100% safe
against freeze-up with water coils. Glycol
solutions or brines are the only safe media for
operation of water coils with low entering air
conditions.
2. Connect the WATER SUPPLY TO THE BOTTOM
CONNECTION on the air leaving side and the
WATER RETURN TO THE TOP CONNECTION on
the air entering side. To insure proper venting, an
external air vent in the piping is recommended.
Connecting the supply and/or return in any other
manner will result in very poor performance. Be
sure to replace factory installed grommets around
coil connections if removed for piping. Failure to
replace grommets will result in water leakage into
the unit and altered performance.
CONTINUOUS WATER CIRCULATION THROUGH
THE COIL AT ALL TIMES IS HIGHLY
RECOMMENDED.
5. Pipe sizes for the system must be selected on the
basis of the head (pressure) available from the
circulation pump. The velocity should not exceed
6 feet per second and the friction loss should be
approximately 3 feet of water column per 100 feet
of pipe.
3. The air vent at the uppermost point should be
temporarily opened during system start-up to
11
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