Product Overview

BAC-1xx63/1xxx63 Series (6 Relays and 3 Analog Outputs) Section 46 Application Guide S
OAT Econ Loop “P” factor
65 15
53 15
50 15
45 22.5
40 30
30 30
During occupied mode, the mixed air temp setpoint is determined based
on a reset schedule. If the space temperature is at or below the active
cooling setpoint, the mixed air temp setpoint is MAT Max Temp (68.0°
F or 20.0° C). If the space temperature is 2.0° F (1.1° C) above the active
cooling setpoint, the mixed air temp setpoint will be MAT Min Temp
(53.0° F or 11.7° C). The mixed air setpoint will vary linearly in between.
MAT Min Temp and MAT Max Temp are adjustable from the U/I.
During unoccupied mode, if the space temp exceeds the cooling setback
setpoint by cooling proportional band and the econ mode is enabled, the
outside air damper shall open as called for by the mixed air temp loop.
The outside air damper shall modulate to maintain MAT Min (53.0° F
or 11.7° C) until the space temp reaches the cooling setback setpoint, at
which point it shall close. If at any time during unoccupied mode the
economizer mode is disabled based on OAT, the outside air damper will
close.
If the system mode is set to “heating” during occupied mode, the
damper will open to minimum position when the fan is on. If the system
mode is set to “heating” during unoccupied mode or is set to “o” in
any occupancy mode, the outside damper will close. If at any time there
is a fan alarm, the outside air damper shall shut.
If the mixed air temp drops below the low limit alarm temp, a low
limit alarm is generated and the outside air damper will close. Other
safety actions are taken and described in their respective sections below.
DCV (Demand Controlled Ventilation)—General Information
NOTE: See also CO2 Sensors and DCV on page 25.
In addition to the Economizer option, BAC-12xxxx/13xxxx/14xxxx
models have the Demand Control Ventilation (DCV) option available.
DCV combines several options and modes into eciently controlling the
outside air damper . DCV is enabled by seing DCV to one of the three
congurations.
The various Outside Air (OA) % seings that are available are the per-
centage that the OA damper is open and not the percentage of OA ow.
These seings should be measured and set accordingly.
The controller is designed to operate without an outside CO
2
sensor us-
ing a reference CO2 Base level (400 ppm default). This seing is adjust-
able from the U/I and should be set to the local average outdoor CO
2
level. If an outdoor CO
2
reference is desired, a spare input on the Flex-
Stat can be used and mapped to AV60. This should be done at priority 8
or higher (higher priority = lower number).
The three types of DCV congurations available are:
• BASIC—Provides simple DCV, modulating the outside air damper
in direct response to the current CO
2
level with respect to its set-
point. Basic DCV is much more energy ecient than no DCV at
all, while maintaining adequate IAQ (Indoor Air Quality). It is the
easiest DCV method to congure. However, where VOCs, radon, or
other pollutants become excessive during unoccupied times (with no
ventilation), the FlexStat’s Standard or Advanced DCV conguration
is recommended.
• STANDARD—When the BAC-13xxxx seings are properly cong-
ured, complies with CA Title 24, Section 121(c). This would also
apply to a properly congured BAC-12xxxx with a remote SAE-10xx
CO
2
sensor. Standard DCV, under most conditions, is somewhat less
energy ecient than Basic, but it enhances IAQ.*