MASTERTROL® AUTOMATIC BALANCING SYSTEM™ (MABS®) EZ ZONE (EZ-2 AND EZ-4) CONTROL PANELS
9 69-1360–2
OPERATION
Sequence of Operation
On a call for heating or cooling, the zone damper to the calling
zone stays open, and the dampers close to the zones that are
not calling. The MABS EZ panel brings on the heating or
cooling and conditioned air is delivered to the calling zone
until the zone is satisfied. When the call is satisfied, the
system enters the Purge mode. This holds open the damper
of the last zone calling and purges into that zone. The Purge
time can be set to three and one-half or two minutes.
Individual Zone Fan Control
When all zones are satisfied, each zone thermostat Fan
switch controls the fan operation for each zone. When
circulation is desired, place the Fan switch in the On position.
The fan runs and closes the dampers to the zones where the
Fan switch is set to Auto.
Multi-Stage Operation
MABS-EZ can control up to two stages of heating and cooling
using singe-stage thermostats. The panel uses a timer to
control the second stage and is adjustable from five minutes
to 30 minutes using DIP switches 5, 6, and 7. See Table 4.
When a call for heating or cooling is not satisfied within the
time set on the stage time, the panel energizes the second
stage of heat or cool and both stages remain on until the call
is satisfied.
Changeover Operation
The MABS EZ panel uses a standard heating and cooling
thermostat for each zone to allow any zone to call for heating
or cooling. When opposite calls are made from different
zones, MABS EZ accepts the first call. Once the first call is
satisfied, or a maximum of 20 minutes elapses from the start
of an opposite call, MABS EZ allows the opposite call.
Automatic changeover thermostats can also be used to
provide automatic zone changeover.
When opposite calls occur, the panel ensures that both calls
are acknowledged. If the first call is not satisfied within 20
minutes, the panel drops the existing call and goes into the
Purge mode. After completion of the Purge, the panel
switches to the opposite mode until it is satisfied or until 20
minutes elapses.Then it goes back into the Purge mode and
back to the original call. The system continues to switch back
and forth until both calls are satisfied.
Purge Mode
At the end of every call for heat or cool, the panel enters a
Purge mode that holds the last zone damper open for three
and one-half or two minutes. During this time, the panel or
HVAC equipment can operate the fan. Purge is a time delay
that prevents short cycling of the heating and cooling
equipment after each call. The Purge LED lights when the
system is in Purge mode. Press Purge Override button when
the purge LED is lighted to override Purge.
Table 4. Stage timer configuration.
Minutes DIP Switch 5 DIP Switch 6 DIP Switch 7
5 Off Off Off
8On Off Off
10 Off On Off
12 On On Off
15 Off Off On
20 On Off On
25 Off On On
30 On On On
Table 4. Stage timer configuration.
Minutes DIP Switch 5 DIP Switch 6 DIP Switch 7
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