68
Communication Failures
Communication is critical for ERV operation. It can fail on two
different paths; between the UPC and the rooftop (LEN), or be-
tween the UPC and the EXCB. This makes the UPC critical to
ERV operation. Make sure the UPC DIP switches and rotary
switches are set correctly. Make sure the board hardware jumpers
are set on EIA 485 and 2W. During normal operation the 4 com-
munication LEDs will flash interchangeably. If all 4 LEDs are not
flashing then there is a communication problem. Check connec-
tions between Port 1a and rooftop’s LEN connection and Port 2
and the EXCB J23 (verify with the proper unit schematic).
The ERVs, LCD screen will show specific communication fail-
ures when they occur. Use the LCD screen to help troubleshoot
communications failures. If communication is established, the
LED shows “communication connected”.
COMM FAILURE1 – UPC TO LEN FAIL
This will be displayed if the EXCB can communicate with the
UPC, but the UPC does not receive information from the
Com-
fort
Link controller. This will occur if the cable is pinched or
disconnected, wired wrong or loose, or if the UPC is config-
ured wrong.
COMM FAILURE2 – UPC TO EXCB FAIL
This will be displayed if the EXCB cannot communicate with
the UPC. This will occur if the connection between them is dis-
connected or pinched. This will also occur if the UPC does not
have power or software, or if it has an error or configured
wrong.
On-Board Pressure Transducers
The EXCB uses on-board pressure transducers to measure the
air pressure of the incoming outside air and the building ex-
haust air. The CFM values are then calculated based on these
readings and the fan speed. There is a pressure transducer for
the outside air and one for the exhaust air. These are screwed
into the EXCB board to J24 and J25 respectively. They have
three pins: IN, GND, and OUT. The IN pin is 5vdc input power
and GND is the common or ground pin. The OUT pin will be
0.26 to 4.5vdc based on the pressure reading. There are two
different transducers used, two inch of water column (in.wg)
and 5 in.wg. Table 28 shows the voltage/pressure characteris-
tics of each.
MAJOR SYSTEM COMPONENTS
General
The 48/50HC single package rooftop units contain the
Com-
fort
Link electronic control system that monitors all operations of
the rooftop. The control system is composed of several main con-
trol components and available factory-installed options or field-in-
stalled accessories as listed in sections below. See Figs. 24-31 for
typical control and power schematics for 48HC and 50HC. Refer
to the base unit installation instructions or actual unit control box
for specific unit wiring diagrams.
Table 28 — Transducer/Voltage vs. Pressure
Voltage (vDC)
Pressure (in.wg)
2 in. transducer
5 in. transducer
<= –0.26
0.00
0.00
0.5
0.12
0.28
1.0
0.34
0.87
1.5
0.53
1.46
2.0
0.82
2.05
2.5
1.06
2.64
3.0
1.30
3.23
3.5
1.52
3.82
4.0
1.76
4.41
4.5
2.00
5.00
Summary of Contents for /50HC 04-28
Page 69: ...69 Fig 24 Typical Control Diagram for 48HC 04 14 Units 48HC 08 09 shown ...
Page 70: ...70 Fig 25 Typical Power Diagram for 48HC 04 14 Units 48HC 08 09 shown ...
Page 71: ...71 Fig 26 Typical Control Diagram for 50HC 04 14 Units 50HC 14 shown ...
Page 72: ...72 Fig 27 Typical Power Diagram for 50HC 04 14 Units 50HC 14 Non Humidi MiZer shown ...
Page 73: ...73 Fig 28 Typical Control Diagram 48HC 17 28 Units ...
Page 74: ...74 Fig 29 Typical Control Diagram 50HC 17 28 Units ...
Page 75: ...75 Fig 30 Typical Humid MiZer Power Diagram and Component Arrangement 48 50HC 17 28 Units ...
Page 76: ...76 Fig 31 Typical Non Humid MiZer Power Diagram and Component Arrangement 48 50HC 17 28 Units ...
Page 89: ...89 Fig 42 Modulating ERV Wiring Schematic ...
Page 90: ...90 Fig 43 EnergyX ERV Control Box Component Layouts ...
Page 101: ...101 Fig 59 Exhaust Fan Assembly Removal Exhaust Fan Assembly ...
Page 141: ......