6
4. Secure the dehumidistat ground wire (typically the green
lead) to the ground screw on the modular blower.
NOTE:
Ground wire may not be present on all
dehumidistats.
5. Turn ON power to modular blower.
To enable the dehumidification function, move the dehumidi-
fication dipswitch from OFF to ON.
7
8
ON
OFF
DEHUM
Unused
Move to the ON position
to enable dehumidification
C
IRCULATOR
B
LOWER
This modular blower is equipped with a variable speed circu-
lator blower. This blower provides ease in adjusting blower
speeds. The Specification Sheet applicable to your model
provides an airflow table, showing the relationship between
airflow (CFM) and external static pressure (E.S.P.), for the
proper selection of heating and cooling speeds. The heating
blower speed is shipped set at “21 kW”, and the cooling blower
speed is set at “D”. These blower speeds should be adjusted
by the installer to match the installation requirements so as to
provide the correct electric heating CFM and correct cooling
CFM.
Use the CFM LED (green), adjacent to the integrated control
module electric heat connector to obtain an approximate air-
flow quantity. The green CFM LED blinks once for each 100
CFM of airflow.
1. Determine the tonnage of the cooling system installed
with the modular blower. If the cooling capacity is in
BTU/hr divide it by 12,000 to convert capacity to TONs.
Example:
Cooling Capacity of 30,000 BTU/hr.
30,000/12,000 = 2.5 Tons
2. Determine the proper air flow for the cooling system.
Most cooling systems are designed to work with air flows
between 350 and 450 CFM per ton. Most manufacturers
recommend an air flow of about 400 CFM per ton.
Example:
2.5 tons X 400 CFM per ton = 1000 CFM
The cooling system manufacturer’s instructions must be
checked for required air flow. Any electronic air cleaners or
other devices may require a specific airflow; consult installa-
tion instructions of those devices for requirements.
3. Knowing the modular blower model, locate the high
stage cooling air flow charts in the Specification Sheet
applicable to your model. Look up the cooling air flow
determined in step 2 and find the required cooling speed
and adjustment setting.
Example:
A MBVC1200 modular blower installed with
a 2.5 ton air conditioning system. The air flow needed
is 1000 CFM. Looking at the cooling speed chart for
MBVC1200, find the air flow closest to 1000 CFM. A
cooling airflow of 1000 CFM can be attained by setting
the cooling speed to “C” and the adjustment to “Normal”
(no adjustment).
4. Locate the blower speed selection DIP switches on
the integrated control module. Select the desired
“cooling” speed tap by positioning switches 1 and 2
appropriately. Select the desired “adjust” tap by
positioning switches 3 and 4 appropriately. Refer to
the following figure for switch positions and their
corresponding taps. Verify CFM by counting the
number of times the green CFM LED blinks.
5. Continuous fan speed is 30% of the modular blower’s
maximum airflow capability.
Example:
If the modular blower’s maximum airflow
capability is 2000 CFM, the continuous fan speed will
be 0.30 x 2000 CFM = 600 CFM.
1
2
1
2
1
2
1
2
OFF
OFF
OFF
OFF
ON
ON
ON
ON
Tap A
Tap B
Cooling Air flow Speed Tap (*indicates factory setting)
Tap C
Tap D*
3
4
Normal*
+10%
Air flow Adjust Taps (*indicates factory setting)
-10%
Normal
OFF
OFF
OFF
OFF
ON
ON
ON
ON
3
4
3
4
3
4
6. The multi-speed circulator blower also offers several
custom ON/OFF ramping profiles. These profiles may
be used to enhance cooling performance and increase
comfort level. The ramping profiles are selected using
DIP switches 5 and 6. Refer to the following figure for
switch positions and their corresponding taps. Refer
to the bullet points below for a description of each
ramping profile. Verify profile selection by counting
the green CFM LED blinks and timing each step of
the ramping profile.
•
Profile A provides only an OFF delay of one (1) minute
at 100% of the cooling demand airflow.
OFF
100% CFM
100% CFM
1 min
OFF
•
Profile B ramps up to full cooling demand airflow by
first stepping up to 50% of the full demand for 30
seconds. The motor then ramps to 100% of the
required airflow. A one (1) minute OFF delay at 100%
of the cooling airflow.
50% CFM
1/2 min
100% CFM
100% CFM
1 min
OFF
OFF
Summary of Contents for MBVC
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