Control Methods; Timeshare; Differential - Robertshaw SlimZone Premier Installation And Operation Manual

SMART FAN ENABLE
When Smart Fan is enabled and constant fan is selected at the control module (global constant
fan), the fan will remain ON during the occupied period and go to the auto mode during the
unoccupied period. Note that all zones have to be in the unoccupied (night) period for the fan
to go in the auto mode. If auto fan is selected at the control module, local fan demands are
processed normally; fan will be ON to zones requesting constant fan.
5.5

CONTROL METHODS

5.5.1 TIMESHARE

The timeshare control method will change over from heating to cooling and vice versa as
follows:
A. No equipment calls are serviced until the number of zones calling for either heating or
cooling meet the requirements for the number of zones needed to activate first stage. The
first mode to satisfy the requirements will be serviced.
B. Upon initiating the equipment call, the control module starts a 20 minute internal timer.
Calls for the opposite equipment mode are ignored during these 20 minutes.
C. If the current call is not satisfied after the first 20 minutes and calls for the opposite
mode have met the requirements to activate the first stage of equipment, the control
module will changeover to the opposite mode and reinitiate the 20 minute timer.
NOTE:
- In heat/cool mode, the control module will changeover to the opposite equipment
mode after the minimum OFF time of the equipment it just serviced.
- In heat pump mode, changeover is done by activating the opposite reversing valve
output (O/B terminals); the compressor is not turned OFF.
D. The control module will continue in this fashion, changing over every 20 minutes, until the
zones are satisfied. Note that the control module will service an equipment call only if the
number of zones calling meet the requirements to activate that stage. The moment the
number of zones calling is not sufficient to activate that stage, the module will consider
this call to be satisfied.
UPSTAGING AND DOWNSTAGING
When the control module changes over to the opposite equipment mode and sufficient number
of zones are calling for second stage, the module will start with the first stage. If after 5 minutes
the number of zones calling is still sufficient, the module will activate the second stage.
Subsequent stages are activated, one every 5 minutes, providing the number of zones calling
is sufficient. In the heat pump mode, the auxiliary heat is delayed a further 15 minutes after the
last compressor stage.
Downstaging occurs in a similar manner when the number of zones calling decreases to a value
below the number of zones required to activate that stage.

5.5.2 DIFFERENTIAL

In the differential control method, the control module determines the difference between the
number of zones calling for heating versus the number of zones calling for cooling. The
difference calculated is then compared to the number of zones required to activate the first
stage of equipment for the mode which has more calls, and if sufficient, that stage will be
activated and zones calling for that mode will be serviced.
UPSTAGING AND DOWNSTAGING
If the calculated difference between zone calls is sufficient to activate the second stage of
equipment for the mode currently activated, then the module will upstage. Downstaging occurs
when the number of zones calling decreases and the calculated difference falls to a value below
the number of zones required to activate that stage.
16 SlimZone Premier