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LCBS CONNECT SOLUTION

31-00118EFS—01

Fig. 11.

Multispeed Fan Summary

Please take the time to understand the physics of the fan(s) you intend to control; wire them up properly and
determine how you are going to control them. It is essential that you read and understand the theory and
operation of the multispeed fan options and how you intend to control them. It is absolutely essential that
you understand concepts shown above so that you can commission an effective fan control strategy.
Contact your Honeywell LCBS Connect sales and support professional for assistance.

THEORY AND OPERATION ACCESSORY LOOPS

One of the key differences between residential and commercial applications is the presence of HVAC equipment, along
with commercial constant volume air handling units, rooftop units, and split systems. Vestibules, entry ways have unit
heaters, perimeter zones have electric and hot water radiant heaters, stock and storage rooms have unit heaters. All of
these HVAC types can be controlled by the LCBS Connect controllers. Lighting and refrigeration systems can also be
controlled by Accessory Loops. As long as we pay careful attention to HVAC and electrical physics of controlled loads, we
can do a great job of controlling most HVAC and other ancillary heating, cooling, and lighting loads.

How do Accessory Loops work?

For all intents and purposes, if you understand and can define inputs and outputs do in the control sequence, you will be
able to duplicate it with an LCBS Connect accessory loop. Two common examples that will demonstrate the use of LCBS
Connect accessory loops will be described. First will be a simple blower fan and gas heater, typically found in warehouses,
loading docks, stocking areas. Second will be a photocell loop that is commonly applied to turn outdoor lighting on and
off based on outdoor ambient light level.

Heating Blower Coil

Assume that a heating blower coil is in a loading dock and that the dock is open from 6 AM in the morning to
midnight. Because this is a heating blower coil, our primary requirements during occupancy would be 1] the
comfort of the loading dock employees and 2] good even temperature control. During unoccupied times from
midnight to 6 AM, out primary requirement is keeping pipes, product, and equipment from freezing in the
loading dock, warehouse area.

Setting up the application

First, a sensor should be selected in the controlled space proximate to the blower coil. The desired control set point range
should be considered in the selection process. Let's assume that we want to control the temperature in the loading dock
at 65°F during occupancy and we want to control the temperature in the loading dock during unoccupied time at 40°F. It
is desirable to ensure that blower coil is not over cycled, so choose the type to be a Staged Thermostat that will ensure
standard cycling behavior. Further we will configure, the PID action to be reverse acting (heating). This drives the
selection of the right room, space, zone sensor, type and action. We'll pick the TR40 sensing only device that has a range
from 32°F to 110°F. Secondly, we need to determine how to operate the control circuit to energize and reenergize the
blower coil fan and the gas or electric heating circuit. We need to examine the rating of the on-board relay on the LCBS
Connect controller. After brief investigation, we find that we can control a 1.0 A circuit at 24 VAC. This stated, we can
probably interrupt a low voltage control circuit directly or provide a line voltage relay with a low voltage relay coil.

NOTE: If you are controlling a line voltage load (110 VAC+) you need to provide a relay with an appropriate low volt-

age coil to control the control load.

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