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example, if the room temperature was 67ºF when the room sensor was
disconnected, the displayed room temperature will be 67ºF for approximately
5 minutes. After this period has elapsed, the unit will default to a failsafe
mode during which the discharge air temperature will be maintained at 70°F.
The displayed room temperature on the
BACview
will be 45°F. If the unit
control module then loses power any time after the loss of communications
and is repowered, the room temperature will be displayed as 0ºF until the
communications failure is rectified. Is the room sensor wired correctly and
securely in the terminal connectors on the back of the room sensor as well as
at the Rnet input on the left side of the unit control module?
a.
No. Correct wiring and securely tighten connections. Check to see if
the alarm has turned off, indicating the problem has been resolved.
b.
Yes. Internal room sensor failure. Replace room sensor.
Glossary
BACview
– A four line by forty character display used to change setpoints and monitor
the unit’s operation. See
BACview
.
Equivalent temperature rise
– Simply stated this value is the actual temperature rise
generated by the unit at any given time. More precisely stated, it is the quantity of outside
air raised to the discharge air temperature, plus, the quantity of return air raised to the
discharge air temperature. It is equivalent to the heat actually delivered to the space. The
purpose for this in the burner control scheme is to limit the burner’s firing rate, based on
the percentage of outside air, and thus the carbon monoxide generated by the unit.
Expressed mathematically it is: T
eq
= %OA (T
da
– T
oa
) + %RA (T
da
– T
ra
)
PID Control or loop –
Proportional, Integral, Derivative control, a common control
scheme used in modulating HVAC systems.
Remote Control Panel
– The remote control panel is a cover plate with one or more of the
following controls and indicators: unit enable/remote temperature setpoint pot, remote
damper control pot, speed control switch, fill/drain switch, fan on, clogged filter, high
speed, low speed, burner on, cool on lights. This cover plate fits on a standard 3 gang
electrical switch box. See
BACview
.
WebCTRL
– A web based graphical user interface, which provides the user access to the
unit via the internet.
