Carrier 62ME - Manual (Page 75)

75
• EXH blower motor is turned on.
• The two-position damper is open (if used).
• The stop/jog option will periodically rotate the ERV
wheel to clean it during wheel bypass operation. This
feature is factory set to activate every 10 minutes, for
20 seconds of operation. Both settings can be adjusted
from 0 to 10 minutes.
UNOCCUPIED MODE — While in unoccupied mode, when
below the low temperature lockout set point, the ERV wheel is
off, and only the two-position damper option is opened to
allow free cooling when desired. The dampers are controlled
by either the ERV Timer option (scheduling program) or the
CO
2
sensor input. Additionally, the frost protection and preheat
options are also off. The low temperature lockout (LTLO)
function locks out the 62M ERV if the outdoor-air temperature
entering the wheel is below the set point. The LTLO is factory
set at –10 F, and can be field adjusted from –30 F to 100 F.
When above the low temperature lockout set point and
cooling is desired the economizer or wheel bypass option is
also used. Depending on the option used with the 62M ERV,
several sequences of operation could occur.
Unoccupied Mode, with the Economizer Accessory — When
using the economizer option, this allows for up to 100% out-
side air to be brought in for free cooling. During free cooling,
no mechanical cooling is operating and the following occurs:
•
ERV wheel is turned off.
• Outdoor air blower motor is off.
• EXH blower motor is off.
• Two-position OA damper option is closed (if used).
• Two-position EXH damper is open (if used).
• The stop/jog option will periodically rotate the ERV
wheel to clean it during wheel bypass operation.
When using the economizer option and mechanical cooling
is operating, the economizer should be closed or at the mini-
mum position.
Unoccupied Mode, with the Wheel Bypass Option — When
using the wheel bypass option (with the stop/jog option), this
allows free cooling through the wheel limited by the ERV cfm
limits. With this option the unit can be in free cooling or not
depending on the temperature of the OA compared to the
set point. When in free cooling:
•
ERV wheel is turned off.
• Outdoor air blower is on.
• EXH blower motor is on.
• Two-position damper is open (if used).
When not in free cooling:
• ERV wheel is turned off.
• Outdoor air blower motor is turned off.
• EXH blower motor is turned off.
• Two-position damper is closed (if used).
SERVICE
Removing Wheel Segments for Cleaning
(62M170-950 Units)
1. Unlock and open the segment retaining brackets on both
sides of the selected segment opening. Refer to Fig. 83.
2. Gently lift segment outward.
3. Close segment retaining latches and rotate wheel 180 de-
grees to remove next segment. Follow this pattern to
remove all segments. This pattern will help keep wheel
balanced.
To install the segments see the Installing Wheel Segments
(62M075-950) section.
Removing and Installing Non-Segmented Wheel
for Cleaning (62M040 Units) —
Non-segmented ener-
gy transfer wheels are secured to the shaft and bearing support
beam by a Phillips head screw and hub cover. See Fig. 84.
To remove the energy transfer wheel, follow Steps 1-4
below. (See Fig. 84.) Reverse procedure for wheel installation.
1. Remove front seal assembly (pulley side of cassette) if
present.
2. Remove belt from pulley and position temporarily around
wheel rim.
3. Remove the hub cover from the wheel. Note the wheel to
shaft alignment pin under the hub cover. Ensure this pin
engages the notch at the end of the shaft when reinstalling
the wheel.
4. Pull the wheel straight off the shaft. Handle wheel with
care to prevent distorting of the wheel.
Disconnect electrical power before servicing energy recov-
ery cassette.
Alignment
Pin
Cassette
Housing/Frame
Shaft
Bearings (2)
Hub Cover Wheel &
Hub
Fig. 83 — Unlocking the
Segment Retaining Brackets
Fig. 84 — 62M040 Energy
Transfer Wheel Assembly