Johnson Controls York VERSECON YSWD 012, Installation Operation & Maintenance

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JOHNSON CONTROLS
FORM 145.05-NOM1 (708)
Tristate Modulated Heat
The following parameters must be programmed through
the “Setpoints” s ection of the Keypad / Display.
“HT STG –1/TRI-2”
– For Tristate Modulated Heat this
parameter needs to be set to 2.
The Tristate Modulated Heat option uses a three position
valve; open, closed and hold. When the variable
percentage output is greater than 50%, the control will
send an open signal to the valve for five seconds. During
this time, the heating capacity will increase. The control
will wait two minutes with the valve in the hold position
(no output). It will then look at the variable percentage
output again. If the output is still greater than 50%, it
will send an open signal to the valve for five seconds.
The control will then wait two minutes with the valve in
the hold position and then look at the variable percentage
output. If the output is still greater than 50%, it will
go through the open sequence again. If the output is
between 10 and 50%, the control will maintain the valve
output in the hold position (no output).
If the output is less than 10%, the control will send a
closed signal to the valve for five seconds. During this
time, the heating capacity will decrease. The control
will wait two minutes with the valve in the hold position
(no output). If the output is still less than 10 %, the
control will initiate a close signal. If the output is
between 10 and 50%, it will remain in the hold mode
(no output). If the output is greater than 50%, the control
will initiate an open signal.
If the freezestat safety switch opens for ten seconds, the
control will ignore the 50% variable percentage output
requirement and will continue to send an open signal
to the valve for five seconds every two minutes as long
as the freezestat switch remains open.
The 24 VAC open signal originates at Terminals 13
and 14 of the DO7 connector on the Expansion Control
Board.
The 24 VAC close signal originates at Terminals 15
and 16 of the DO8 connector on the Expansion Control
Board.
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