Honeywell LCBS User Manual

LCBS CONNECT SOLUTION
31-00118EFS—01 22
As mentioned above, cost of VFDs have decreased over the years, they are efficient, and they can be preprogrammed to
specific speeds. Because of their electrical construction, VFDs can gradually increase supply fan speed, providing supply
fan "soft start." This avoids starting jolts that create excess noise and mechanical wear on the system
Electronic Direct Drive Motor (ECM, et al.) A direct-drive motor can received a control signal from the LCBS Controller
that will change the supply fan motor speed. You will find that these are typically low horsepower applications, usually
found is system less than five (5) tons. You will find that the direct-drive motor takes up no additional space in the base
rooftop and can be field configured through the LCBS Controller.
LCBS Connect can perform all currently accepted multispeed supply fan strategies. If you encounter an ECM type supply
fan motor or two speed, two winding fan, we can control it. For retrofit application, it is our recommendation that the
application of a VFD makes most sense. It provides ultimate ability to alter supply fan motor speed and provides soft start
operation for the fan motor. Make sure you are conscious of application of a VFD with the motor you are attempting to
control.
How it Works VFD Application and Direct Drive "ECM" Motor
The LCBS Connect controller offers some groundbreaking control technology to take advantage of ever lower costs of
variable frequency drives. The Honeywell approach permits the applier to assign any fan speed to any heating, cooling,
ventilation mode. The following table shows the options for VFD control.
Table 5.
Example of VFD Fan Control
Let's assume that I want to reduce fan speed during single stage of heat and ventilation mode at the same low rate 40%. I
want to reduce fan speed during first stage cool to 60%. I want the fan to run at 80% for multistage heat and cool HVAC
modes. Please refer to the diagram below to describe how we want the system supply fan will work.
Fig. 10.
Following the diagram from left to right, just above and to the left, note that if there is a call for "unoccupied heat," the fan
cycles on with the call for single stage heat, per single heat mode at 40%. When the call for heat abates, the fan cycles off
during "unoccupied" period. During Intelligent Recovery, call for heat occurs again and fan is energized to 40% speed, per
"single heat" mode. When system enters "occupied mode," fan speed is programmed for 40% and fan runs at this level. We
assuming that economizer carries the cooling load within "vent mode" and fan continues to run at 40%. We have a call for
mechanical cooling. When first stage of cooling is energized, fan runs at 60%. The call for cooling continues and second
state of cooling is energized. Per "multistage cooling" mode requirement, fan runs at 80%.
Without "multispeed fan" and variable frequency drive application, the fan operates as shown, to your left. The "yellow
area" indicates energy saving potential by running the fan with the Honeywell LCBS Connect controller algorithm.
Wow!
CONTROL CONDITION
ENCOUNTERED, MODES DESCRIPTION
UP TO SIX FAN
SPEED CHOICES
VENTILATION MODE NO CALL FOR HEATING, COOLING DURING OCCUPANCY 40-100%.
SINGLE STAGE HEATING CALL FOR ONE STAGE OF HEATING 40-100%.
MULTIPLE STAGE HEATING CALL FOR ONE, TWO, THREE STAGES HEATING 40-100%.
SINGLE STAGE COOLING CALL FOR ONE STAGE OF HEATING 40-100%.
MULTIPLE STAGE COOLING CALL FOR ONE, TWO, THREE STAGES HEATING 40-100%.
OTHER MODE DESCRIBE, DEFINE ANOTHER MODE 40-100%.
TIME
100
90
80
70
60
50
40
30
20
10
0
FAN SPEED (GRAY BAR)
TEMPERATURE (GRAY LINE)
SINGLE
HEAT
VENT
OFF
FAN SPEED
HEATING SETPOINT
MCR36671
SINGLE
HEAT
COOLING SETPOINT
SINGLE
COOL
MULTISTAGE
COOL

Honeywell LCBS Specifications

General

Brand	Honeywell
Model	LCBS
Category	Controller
Language	English