Control Operation Overview Chore-Tronics® 2 Control
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MT1843B
Tunnel Mode
The Main curtains, if used, are given continuous close signals. The tunnel
curtain is either given a continuous open signal, or is adjusted to control static
pressure. The outputs that are allowed to operate in Tunnel Mode turn on and off
per screen 4 trying to satisfy their temperature sensors assigned in screen 13.
Mode Transitions
There are six possible mode transitions:
1.Power to Natural
2.Power to Tunnel
3.Natural to Power
4.Natural to Tunnel
5.Tunnel to Natural
6.Tunnel to Power
The sequences of events that happen for each transition are very different and deal
with the various considerations that must be dealt with in order to safely get from one
mode to another.
Power to Natural
In the Power mode, the main and tunnel curtains are given a continuous close
signal. When the Power mode sensor(s) reach the Natural Allowed temperature
in Screen 4, the main and tunnel curtains will open for the amount of time
required for the first opening movement defined in Screen 14, curtains tab. The
control calculates this amount of time based on the speed specified in Screen 14,
curtains tab for each curtain (Main 1, Main 2, and Tunnel).
If the temperature drops 0.6 degrees F, within the first two minutes after the
curtain(s) reach the desired first opening, the control will immediately close all
the curtains and return to Power mode. This is known as the "fast temperature
drop test". If the temperature does not drop this fast, the control will proceed
with normal natural operation (see previous section).
Natural to Power
The natural to power transition occurs when the Main Curtain returns to it’s “first
opening” position, while going closed. If there are two Main Curtains, (Main1
and Main2), the transition occurs as soon as both Curtains are at or past their first
opening positions in the process of going closed. The temperature must be below
the Main Curtain Range for the curtain(s) to move in the close direction, but
temperature by itself does not cause the transition from Natural to Power Mode.
The Fans that are called for to be on in the Power Mode are delayed from coming
on until the Main Curtain(s) have enough time to get closed. The Tunnel Curtain
is given a continuous close signal during the entire Natural to Power transition.
Heat zone outputs are disabled for an additional 2 minutes to minimize fuel waste
while the temperatures stabilize after the transition is over.
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