Installation manual
Page 8 / IM 178
Controls, Settings, and Functions
Table 2 presents a listing of all the unit control devices. Included in the table are the device symbol, a description of the device, its function, and any reset information, its location,
any device setting, any setting ranges, differentials, and the device part number.
Table 2. Controls, settings and functions
SYMBOL DESCRIPTION FUNCTION RESET LOCATION SETTING RANGE DIFFERENTIAL PART NO.
ADI ADI Board Collects and conditions analog and digital inputs. N/A Main control box N/A N/A N/A 658160B-05
DHL Duct high limit Prevents excessive VAV duct pressures; shuts off fan. Auto Main control box 3.5" w.c. (871.8 Pa) 0.05–5.0" w.c. 0.05" w.c. 654938B-01
(12.5–1245.4 Pa) (12.5 Pa), fixed
FS1 Freezestat Shuts off fans, opens heating valve and closes out- Auto Heating section 38°F (3°C) or 35°F–45°F12°F (7°C), fixed 658300B-01
door damper if low air temperature at coil is detected. as required (2°C–7°C)
MAT Mixed air temperature Senses mixed air temperature; sends signal to N/A Inlet of supply fan N/A 3K ohms at N/A 658295B-03
sensor MicroTech controller. 77°F (25°C)
MCB1 Microprocessor Control Processes input information and controls output re- N/A Main control box N/A N/A N/A 654873B-08
Board lays as appropriate.
OAE Enthalpy control Returns outside air dampers to minimum position Auto Economizer section “B” or as required A – D Temperature: 307067D-02
(electromechanical) when enthalpy is too high. 3.5°F (2°C)
Humidity:
5% fixed
Enthalpy control Returns outside air dampers to minimum position Auto Economizer section Fully CW past “D” A – D N/A 492622B-01
(electronic) when outside air enthalpy is higher than return air (when used with
enthalpy (used with RAE). RAE)
OAT Outside air temperature Senses outside air temperature; sends signal to N/A Under condenser N/A 3K ohms at N/A 658295B-02
sensor MicroTech controller. section 77°F (25°C)
OBA, B, C Output Boards Holds MicroTech solid-state output relays. N/A Main control box N/A N/A N/A 665422B-01:
A, B, or C (16-position)
665422B-02:
(8-position)
665422B-03:
(4-position)
PC5, 6 Filter switch Turns on clogged filter light on status panel. Auto Filter sections As required .05–5" w.c. .05" w.c. 654938B-01
(12.5–1245.4 Pa) (12.5 Pa)
PC7 Differential pressure Senses supply fan pressure to prove airflow. Auto Supply fan section .10" w.c. (25 Pa) .05–5" w.c. .05" w.c. 654938B-01
switch (12.5–1245.4 Pa) (12.5 Pa), fixed
RAE Return air enthalpy sensor Used to compare return air enthalpy to outside air N/A Economizer section N/A N/A N/A 492622B-02
enthalpy (used with OAE).
RAT Return air temperature Senses return air temperature; sends signal to Micro- N/A Return air section N/A 3K ohms at N/A 658295B-05
sensor Tech controller. 77°F (25°C)
SAT Supply air temperature Senses discharge air temperature; sends signal to N/A Discharge air section N/A 3K ohms at N/A 658295B-01
sensor. MicroTech controller. 77°F (25°C)
SB1, 2 Staging Board 1 or 2 Provides stepped cooling or heating control. N/A Main control box N/A N/A N/A See IM 483
SD1 Smoke detector, supply air Initiates unit shutdown if smoke is detected. Manual Discharge air section N/A N/A N/A 490250B-01
SD2 Smoke detector, return air Initiates unit shutdown if smoke is detected. Manual Return air section N/A N/A N/A 490250B-01
SPS1 Duct static pressure Converts static pressure signals to voltage signals N/A Main control box N/A 0–5" w.c. N/A 495450B-05
sensor #1 and sends them to MicroTech controller. (0–1245.4 Pa)
1–6 VDC out
SPS2 Duct static pressure Converts static pressure signals to voltage signals N/A Main control box N/A 0–5" w.c. N/A 495450B-05
sensor #2 and sends them to MicroTech controller. (0–1245.4 Pa)
1–6 VDC out
Building static pressure Converts static pressure signals to voltage signals N/A Main control box N/A -0.25–0.25" w.c. N/A 495450B-06
sensor and sends them to MicroTech controller. (-62.3–62.3 Pa)
1–5 VDC out
SPS5 Dirty filter pressure Sensors pressure drop across first filter bank and N/A First filter section N/A 0–5" w.c. N/A 495450B-05
sensor sends signal to MicroTech controller. (0–1245.4 Pa)
1–6 VDC out
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