KMC Controls BAC-4000 series, Installation, Operation, And Application Manual

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Electric heat for fan
coil units
For AppStat fan coil models that support both on/off and modulating valves,
electric heat can be added to two-pipe systems. Typically this heat is a duct or
baseboard resistance heater controlled by a relay.
When the supply water type is chilled water and there is a call for heat, the
AppStat controls the heating element through output terminal BO5. The
output turns on when the heating loop is greater than 99%. The output is
turned off when the loop falls to 5%. If the supply water type is hot water,
only the water valve output is used to satisfy a call for heat.
Fan operation for
fan coil units
The AppStat supports both modulating fans and fans with one, two, or three
speeds. Speed for either type of fan is determined by the PID loop that is
currently controlling the heating or cooling. Fan speed control is set up from
the user interface by a user with Password 2. See the topic
Set fan coil unit
system options on page 50 .
One, two, and three speed fans
For one, two, and three speed fans, the AppStat controls the fan speed with
terminals FAN-L, FAN-M, and FAN-H.
Single speed fans use terminal FAN-L only
Two speed fans are controlled with terminals FAN-L and FAN-H
Thee speed fans use terminals FAN-L, FAN-M, and FAN-H
The fan output terminals are energized as the cooling or heating loop varies
from 0-100%. Terminal activation is shown in the following table.
Fan L terminal Fan M terminal Fan H terminal
Fan
speed On Off On Off On Off
One Active valve 5% n/a n/a n/a n/a
Two Active valve 5% n/a n/a 95% 80%
Three Active valve 5% 65% 50% 95% 80%
Table 5–1 Fan speed
Modulating fans
The fan starts a modulation fan on a call for either heating or cooling. The fan
runs at the minimum fan speed until the heating or cooling loop reaches 50%.
From 50% to 100% of the loop, the fan speed ramps from the minimum speed
to maximum speed. The minimum and maximum fan speeds are set from the
Section 5: Sequences of operation KMC Controls, Inc.
72 Revision G