Enthalpy Wheel; Modulating Fan; Modulating Outside Air Damper; Energyx Options And Accessories - Carrier 48HC 04-28 Controls, Start-Up, Operation And Troubleshooting

ENTHALPY WHEEL

The enthalpy wheel is the "heat exchangers" of the ERV. It
consists of several wheel segments aligned in a cassette assem-
bly. These are not "filters" but made of a desiccant material.
The wheel is rotated by a motor and belt, no adjustments re-
quired. When the wheel rotates it uses the building exhaust air
to pre-conditions the outside air as it passes through the wheel.

MODULATING FAN

The modulating ERV is equipped with direct drive variable
speed plenum fans for outside air intake and exhaust air. The
motors have built in VFDs that accept a 2 to 10vdc signal from
the EXCB. This 2 to 10vdc signal is used by the VFD to deter-
mine the speed to run the motor at (0 to 100%). Some ERV
models are equipped with multiple outside air and/or exhaust
air fans. The additional motor's signal is parallel off the first
motor through the coupling signal plug. Motor status switches
are also paralleled for additional motors.
Each motor is capable of diagnosing problems within the mo-
tor to provide fan status. The fan status switches are built into
each motor and provide a feedback to the EXCB if a problem is
detected. The feedback signal is a discrete input that is normal-
ly open, when closed the EXCB will initiate the motor status
alarm.

MODULATING OUTSIDE AIR DAMPER

ERV units include a factory-installed modulating outside air
damper. This damper is controlled in parallel with the modulat-
ing intake fan(s). This damper adds static to the outside air and
will be open to the same percentage as the outside air fan(s) is
running. The modulating outside air damper will also close in
the unoccupied mode to prevent unwanted air from being intro-
duced to the rooftop unit.

EnergyX Options and Accessories

The modulating ERV has several optional factory-installed op-
tions and field-installed accessories: Frost Protection, Econo-
mizer, Wheel Motor Status, Filter Maintenance, horizontal
adaptor curb, building pressure sensor, and Outside Air Tem-
pering Kit. Refer to Table 35 for where these options wire into
the EXCB.
ECONOMIZER DAMPER (FACTORY-INSTALLED ONLY)
The economizer damper is a factory-installed option that pro-
vides a wheel bypass damper. This damper is controlled by the
base unit rooftop as an economizer for the purpose of free cool-
ing. The damper is installed adjacent to the ERV wheel to al-
low outside air to flow through it when opened instead of the
wheel. The ERV's outside air fan(s) will run as this damper is
opened to allow proper airflow.

FROST PROTECTION (FACTORY-INSTALLED ONLY)

Frost protection is a factory-installed pressure sensor device
which senses a differential pressure across the wheel. This oc-
curs if frost builds up on the wheel. The sensor closes its con-
tact when the pressure differential is greater than the setpoint.
When the EXCB reads the contact closer it will activate defrost
mode. The setpoint is a dial on the sensor, is adjustable from
0.2 to 2.0 in.wg, and is factory preset to 2.0 in.wg. Changing
this setting may cause false signal causing defrost mode when
not needed.

WHEEL MOTOR STATUS (FIELD-INSTALLED ONLY)

The wheel motor status accessory can be installed in the field
and consists of a wheel motion proxy sensor and a relay. The
wheel motion sensor is aimed at the wheel to detect rotation. If
the wheel does not rotate at the appropriate speed the sensor
will open causing the rotation monitor relay to close a contact
to initiate the wheel status alarm. The motion sensor is factory
set at the highest speed (clockwise until stop) and should not be
changed. Refer to the troubleshooting section for details on the
alarms.

FILTER MAINTENANCE (FIELD-INSTALLED ONLY)

Filter maintenance consists of two field-installed pressure sen-
sor devices which sense differential pressure across the ERV
filters. This occurs if dirt builds up on the filters. There is a
separate pressure sensor for each filter (outside air and exhaust
air). The sensor closes its contact when the pressure differential
is greater than the setpoint. The sensors are wired in parallel, so
when the EXCB reads a contact closer from either sensor it
will activate the filter alarm. The setpoint is a dial on the sen-
sor, is adjustable from 0.2 to 2.0 in.wg, and is factory preset to
2.0 in.wg. Changing this setting may cause false signal causing
false dirty filter alarms.
HORIZONTAL TRANSITION CURB (FIELD-INSTALLED

ONLY)

EnergyX units must receive vertical return. If the application
requires horizontal return then a horizontal transition curb must
be used. Units cannot be field converted to horizontal supply.
To accomplish horizontal supply a horizontal transition curb
must be used.

SERVICE AND MAINTENANCE

EnergyX System Cleaning

WHEEL AND SEGMENT CLEANING

Wheel cleaning periodicity is application dependent. Field ex-
perience shows that offices, schools and other "clean" environ-
ments will often go 10 years before any build up of dust and
dirt is noticed. Other applications such as restaurants, casinos
and factory environments may experience fairly rapid build-up
of contaminants and may require multiple cleanings per year to
maintain airflow and recovery efficiencies.
All air-to-air energy recovery devices will become dirty over
time, even with well-maintained filtration. Proper filtration us-
age and changes will improve the life of the wheel transfer seg-
ments. Once the wheel is exposed to oils, tars or greases in ei-
ther the supply or exhaust air streams, these pollutants deposit
on the rotary surface which then become "sticky" and begin to
attract and hold the dust particles that previously passed thru
the wheel. Over time this particle build up can lead to blocked
airflow passages, loss of recovery, excessive pressure drop
through the wheel and loss of energy savings.
1. Follow steps for wheel and segment removal to remove
the affected energy transfer matrix segments. (For one-
piece wheels 25 inches in diameter and smaller, remove
the entire wheel from the cassette.)
2. Gently brush the wheel face to remove loose accumulated
dirt.
3. Wash the segments with a non-acid based (evaporator) coil
cleaner or alkaline detergent solution. Non-acid based coil
cleaner such as KMP Acti-Clean AK-1 concentrate in a
5% solution has been demonstrated to provide excellent
results. DO NOT use acid based cleaners, aromatic sol-
vents, temperatures in excess of 170°F or steam. Damage
to the wheel will result.
4. Soak the wheel and/or segments in the cleaning solution
until all grease and tar deposits are loosened. An overnight
soak may be required to adequately loosen heavy deposits
of tar and oil based contaminants.
5. Internal heat exchange surfaces may be examined by separat-
ing the polymer strips by hand. (Note: some staining of the
desiccant may remain and is not harmful to performance.)
6. After soaking, rinse the dirty solution from the wheel seg-
ments until the water runs clear.
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