The PAC itself can be installed inside or outside.
The remote sensors must be installed outside.
It is best if the PAC can be installed in as protected of a location as possible. If it is installed outside, it should not be located in direct sun because the sun will fade the faceplate. A drip shield over the PAC will prevent problems from water and ice buildup.
Check to see that any fans that will be under automatic control do not present danger if started unexpectedly. Warning labels are provided to alert anyone who may service the fans.
Some negative pressure system bins do not have adequate air intake openings for fan operation when the bin is empty. The bin may be crushed if the fans are started when it is empty. To prevent this, add more intakes or set up some procedure to assure the PAC is turned to MANUAL OFF when emptying the bin.
The remote sensor box must be installed outside. It contains a temperature and relative humidity sensor that should measure as close as possible the air that will be blown through the grain. It must have "free" airflow around it.
Ideal — remote sensor box
Under the eave on the north side of a building. Or on a post on the north side of a bin with a backplate, drip shield, and side protection from the morning and afternoon sun.
The north side of a bin can be a good location if:
1. A standoff from the bin is used. (Otherwise the cold or the warmth of the bin affects the sensors.)
2. Shielding from morning and evening sun is provided.
DO NOT INSTALL: (the remote sensor box)
► Where sunlight can hit it even for a few minutes a day.
► Where glare can warm it.
► Over a puddle of water.
► Over asphalt that is in the sun.
► With the screen covered holes up.
► Near chemical vapors.
► Directly to a bin.
► Over spoiling grain.
► In an extremely dusty area.
► Without conduit or sealing around the cable.
Turn on power to the PAC until the remote sensors are connected. (If this happens, no permanent damage results, but memory can be corrupted. To correct this, do a RESET of the PAC. See TROUBLESHOOTING on page 32.)
Electrical Installation — Clean Power Supply
It is very important to power the Sentry PAC system with a steady, clean source of power. Usually, a separate line from the load center is adequate. If practical, avoid using the same line as the fan motors.
110 to 130 volts is acceptable.
The PAC's power circuit is fused with a 3/4 amp fast blow fuse.
In cases where voltage variations are common, it may be necessary to install a power conditioner.
Neutral should be 0 volts to earth ground or the PAC will malfunction. This should be verified when other loads are on line.
Isolated Ground — IMPORTANT
Do not ground to a common electrical ground because of the sensitivity of the 5 volt electronic circuit. A separate earth ground rod will reduce problems. It should be installed with nothing connected to it except insulated wire (#12) connected to terminal # 1. Use insulated wire so a static charge can not be picked up from contact with a metal bin.
Momentary Start Relays
Any existing momentary start motor starters must be disabled. This may be done by disconnecting the feedback wire to the coil or by installing a switch to break the circuit. The PAC will not be able to turn off the fans if this is not done. After a power outage, even in MANUAL ON, the PAC will not start the fans for 15 seconds.
Model 2010 family controllers have two sealed contactors that open or close any circuit connected to them. The circuit board has these labeled RELAY 1 (terminals 4 and 5) and RELAY 2 (terminals 6 and 7). They are fused at 3 amps. The line supplying power to the PAC should not be connected to these circuits. Relay 2 is utilized in one of three ways dependent upon the model:
2010 and 2110: Time delay of 1 — 90 seconds after relay 1.
2020 and 2120: Program two.
The PAC does not supply power to these circuits.
If solid wire is used, vibration may work the terminals loose. Bend the wires to create tension that presses the plug in.