Reznor XBWU Unit Installation Manual - Manual (Page 2)

4. Remove barometric exhaust hood from door marked
filter access. Install barometric exhaust hood over
exhaust blower outlet.
5. Remove ERV control access panel to connect field
wiring.
6. Route class II low voltage wire (3 conductor) from
thermostat or energy management through small
bushing in end panel of ERV. See wiring diagram.
a. Thermostat (dependent) - connect in parallel at
rooftop unit with "G", "C" and "W". Then connect
matching color at terminal 1, 2, and 3 respectively
on ERV circuit board.
b. Energy Management - provide +24 VAC to "1" and
common, 24 VAC to "2" terminals on ERV circuit
board.
c. Thermostat (dedicated) - splice into +24 vac (blue
wire) at (control circuit board) transformer
connection run wire to "R" terminal. Then run
another wire from "G" terminal to ERV (control
circuit board) terminal block #1.
7. All electrical connections must conform to any local
codes and current National Electric Codes (NEC) and
Canadian Electric Codes (CEC). Refer closely to unit
wiring diagram in unit and/or in these instructions for
proper wiring connections.
8. Refer to the unit nameplate for minimum circuit
ampacity (MCA) and maximum overcurrent protection
size (fuse).
9. Electrical data is listed on unit rating plate and motor
name plates.
10. Connect line voltage power supply to ERV fuse block
in control box of unit from disconnect switch. See
wiring diagram.
11. Ground unit with a suitable ground connection either
through unit supply wiring or an earth ground.
Note: Unit voltage entries must be sealed weather
tight after wiring is complete.
12. Remove motor access panels. Locate belts fastened
to blower assembly. Install belt onto motor and blower
pulley. Adjust motor sheave to correct blower RPM for
CFM and external static pressure requirements. See
charts in this instruction. Multiple pulley arrangements
are available to meet the entire range.
Caution: Blower speed must be adjusted for the given
external static pressure and airflow (CFM)
requirements. If blower speed is not adjusted
for conditions, possible motor over loading can
occur.
13. Replace access panel onto the ERV unit and secure.
14. Restore power to unit.
15. Cleanup once unit is operating properly, caulk any
open joints, holes or seams to make the unit
completely air and water tight.
16. Leave this instruction manual with owner or in an
envelope to be kept near unit.
VIII - Op er a tion
How It Works
The unit contains an Energy Recovery Wheel (ERW) that
is a new concept in rotary air-to-air heat exchangers.
Designed as a packaged unit for ease of installation and
maintenance, only the connection of electrical power is
required to make the system operational.
When slowly rotating through counter flowing exhaust and
fresh air streams the ERW adsorbs sensible heat and
PAGE 2
latent heat from the warmer air stream and transfers this
total energy to the cooler air stream during the second half
of its rotating cycle. Rotating at 50-60 revolutions per
minute, the wheel provides constant flow of energy from
warmer to cooler air stream. The large energy transfer
surface and laminar flow through the wheel causes this
constant flow of recovered energy to represent up to 85%
of the difference in total energy contained within the two air
streams.
Sensible and latent heat are the two components of total
heat. Sensible heat is energy contained in dry air and latent
heat is the energy contained within the moisture of the air.
The latent heat load from the outdoor fresh air on an air
conditioning system can often be two to three times that of
the sensible heat load and in the winter it is a significant
part of a humidification heat load.
During both the summer and winter, the ERW transfers
moisture entirely in the vapor phase. This eliminates wet
surfaces that retain dust and promote fungal growth as well
as the need for a condensate pan and drain to carry water.
Because it is constantly rotating when in the air stream, the
ERV is always being cleaned by air, first in one direction
then the other. Because it is always dry, dust or other
particles impinging on the surface during one half cycle,
are readily removed during the next half cycle.
During the heating season, when outdoor air temperatures
are below 15
o
F, it is recommended to use the (optional)
low ambient kit (field installed).
Low Ambient Kit is appropriate for climates with limited
HVAC system operation when outdoor temperatures are
below 10
o F.
The frost threshold is the outdoor temperature at which
frost will begin to form on the ERV wheel. For Energy
Recovery Ventilators, the frost threshold is typically below
10
o
F. Frost threshold is dependent on indoor temperature
and humidify. The table shows how the frost threshold
temperatures vary depending on indoor conditions.
FROST THRESH OLD TEM PER A TURE
IN DOOR RH AT 70
o
F
FROST THRESH OLD
TEM PER A TURE
20% 0
o
F
30% 5
o
F
40% 10
o
F
Because Energy Recovery Ventilators have a low frost
threshold, frost control options are not necessary in many
climates. Where outdoor temperatures may drop below
the frost threshold during the ERV operational hours,
exhaust only frost control option is available.
Low Am bi ent Kit (Op tional)
Low Ambient Kit turns off the supply blower when outdoor
temperatures fall below the frost threshold. The exhaust
only thermostat set points are field adjustable. Supply fan
operation is automatically restored when the exhaust air
temperature rises above the thermostat set point.
Provisions for introducing make-up air into the building
when the supply blower is off to avoid depressurization
should be considered.
Re cov ery Wheel Mode
On a thermostat call for blower operation in heating,
cooling or continuous blower, the ERW will rotate between
fresh air and exhaust air streams. Both the fresh air and
exhaust air blowers will also be operating to overcome the
air resistance of the ERV.
IX - Sys tem Check
1.
Disconnect main power.