Lennox Merit CBX25UHV - Air Handler Performance Table

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speed position #4 is 1000 CFM. The + adjustment setting for
that position is 1080 CFM and for the - adjustment setting is
910 CFM. After the adjustment setting has been determined,
choose the remaining speed jumper settings from those
offered in the table in that row.
The TEST pin is available to bypass the BDC3 control and
run the motor at approximately 70% to test that the motor is
operational. This is beneficial primarily in troubleshooting.
G must be energized for motor to run.
COOL JUMPER
The COOL jumper is used to determine the CFM during
either cooling or heat pump operation without a call for
electric heat. These jumper selections are activated for
cooling when Y2 and DS terminals in the Merit
®
CBX25UHV are energized. The are activated for heating
when Y2 is energized.
Applications without the Lennox ComfortSense
®
7000
thermostat will provide 70% of the COOL CFM during
first-stage cooling for two-stage outdoor units. 100% of
COOL speed is provided for systems with a single-stage
outdoor unit.
Applications with the Lennox ComfortSense
®
7000
thermostat, but no demand for de-humidification will
operate as follows: during a first-stage cooling call
(two-stage outdoor unit), the air volume is 70% of the
COOL jumper selection. This arrangement provides for
additional dehumidification during standard first-stage
cooling. See the tables that follow for various scenarios
concerning use of the ComfortSense
®
7000 thermostat
and the Merit
®
CBX25UHV series unit.
For applications with Harmony III
®
zone control, the air
handler CFM volume is determined by the Harmony III
control center. The minimum blower speed is
predetermined at 250 CFM for -018, -024, -030 and -036
units and 450 CFM for -042, -048 and -060 units. This
speed is not adjustable. See footnotes in the blower
performance tables.
With the thermostat set for Continuous Fan and without a
call for heating or cooling, the Merit
®
CBX25UHV provides
50% of the COOL CFM selected.
NOTE - For two-stage heat pumps, air handler will operate
at 70% of the COOL selection until supplemental electric
heat is demanded. At that time, the air handler will operate
at the selected HEAT speed. This arrangement provides
warmer supply air during second-stage heating.
Table 3. Merit
®
CBX25UHV‐018 Air Handler Performance (0 through 0.80 in. w.g. [0 — 200 Pa] External Static Pressure Range)
“ADJUST”
Jumper
Setting
Jumper Speed Positions
“HEAT” Speed First-Stage “COOL” Speed Second-Stage “COOL” Speed
1 2 3 4 1 2 3 4 1 2 3 4
cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm
+ 470 670 890 1080 350 470 620 760 470 675 890 1090
NORM 440 615 810 1000 350 450 560 700 435 610 815 1020
– 400 560 730 910 350 420 520 650 400 575 725 915
NOTES 
The effect of static pressure, filter and electric heater resistance is included in the air volumes listed.
First-stage cooling air volume is 70% of COOL (second-stage) speed setting. Continuous blower speed is approximately 50% of COOL speed setting.
Lennox Harmony III™ Zoning System applications  minimum blower speed is 250 cfm.
Table 4. Merit
®
CBX25UHV‐024 Air Handler Performance (0 through 0.80 in. w.g. [0 — 200 Pa] External Static Pressure Range)
“ADJUST”
Jumper
Setting
Jumper Speed Positions
“HEAT” Speed First-Stage “COOL” Speed Second-Stage “COOL” Speed
1 2 3 4 1 2 3 4 1 2 3 4
cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm
+ 470 690 900 1120 350 470 625 775 480 670 890 1125
NORM 430 640 810 1020 330 450 580 720 430 605 820 1020
– 410 550 720 900 300 405 505 650 390 545 740 930
NOTES 
The effect of static pressure, filter and electric heater resistance is included in the air volumes listed.
First-stage cooling air volume is 70% of COOL (second-stage) speed setting. Continuous blower speed is approximately 50% of COOL speed setting.
Lennox Harmony III™ Zoning System applications  minimum blower speed is 250 cfm.