4.6.2 BAROMETRIC BYPASS SETUP
The BP-10 and BP-12 barometric bypass dampers may be installed in a vertical or
horizontal (up flow or down flow) position. Refer to the installation instructions provided
with the dampers for further information. To set the damper to proper relief control, open
all zone dampers by selecting constant fan on all zone thermostats. Adjust the balancing
mechanism so that the damper blade hovers on the closed position. Lock the balancing
mechanism. If the system has been properly balanced, the barometric bypass damper will
maintain proper system air pressure. As zone dampers close, the bypass damper will open
to relieve excess static pressure.
4.6.3 MOTORIZED BYPASS DAMPERS
Some systems may require a motorized bypass damper. Robertshaw 3 wire bypass dampers
are independently controlled by the Robertshaw EPC-602 static pressure regulator. Mount
the EPC-602 in a position so that the LEDs (light emitting diodes) are visible for checking
operation, and mount the bypass damper so that it is accessible for wiring. Refer to the
installation instructions provided with the EPC-602 for further information.
4.7
CURRENT LIMITED OUTPUT TERMINALS
All output circuits on the SlimZone Classic control panel incorporate a self-resetting current
limiting device which provides protection against excessive current draws caused by
circumstances such as wiring shorts on an output. This device, referred to as a polyfuse,
is activated in general when the current draw exceeds 2.5 Amps. The value and the
duration of the excess current is taken into account. The polyfuse will allow excess
currents of very short duration (i.e., spikes) in order to prevent circuit interruption by noisy
lines or occasional minor surges. In its current limiting mode, the polyfuse reduces the
output current to milliamps.
NOTES:
•
The low leakage current may be sufficient to produce a small voltage reading when
measured with a volt meter with a high input impedance.
•
The panel turns ON the FAULT LED (red) when excess current is being drawn from an
output to warn the user.
When the cause of the excess current has been removed and the current draw is returned
to a value below 2.5 Amps, the polyfuse will reestablish full output current; in some
instances this may take up to 20 seconds. The polyfuse eliminates the need to replace
blown fuses.
4.8
HIGH AND LOW LIMITS
When bypassing conditioned air it is important to consider high and low limit control to
prevent coil freeze up or overheating. An independent high and low limit control is
recommended to protect the HVAC equipment from these conditions. Although there is no
high or low limit control incorporated in the SlimZone Classic control panel, the HILO-200
can be adapted to meet this need. Refer to the installation instructions provided with the
HILO-200 or contact technical services for further information.
SlimZone Classic
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