Trane VUV Installation, Operation And Maintenance Manual page 32

Installation - Controls
Heating
In general, the (CSTI) changeover function will provide heating
if:
• A unit is factory-configured with a changeover coil (cooling/
heating) as the only coil or as the main coil portion.
• SW3 on the CSTI adapter board is turned on, and the
Fprv
parameter set to
changeover functions.
Ehl
– parameter should be chosen if the unit has a
changeover coil without electric heat.
EhFs
– parameter should be chosen if the unit has a
changeover coil with electric heat. Generally, this will
perform the same as the
addition, disable the heating function on electric heat
and on the changeover coil heat if there are fan failures.
The auxiliary heating coil valve will continue to respond
to customer heating requests.
• The motor control board has sensed that there is hot water
available on the supply/bypass line for the changeover coil.
In this case, "hot" water is determined if:
– A 10K NTC thermistor (similar to Trane part number
X13790374010) is wired properly to the motor control
board, through the crossover cables and CSTI adapter
boards.
– The input impedance of the thermistor circuit must be
Aipu
set correctly (the
for CSTI units).
– The temperature sensed is higher than the
parameter.
Ai2b
– The parameter is higher than the
parameter.
a. The temperature is not in the dead-band between the
Ai2b
parameter and the
case, previous state will be retained).
• The customer thermostat is properly hooked up the input
strip 1TB3, and is requesting heating input (V2) based on
the customer heating set point being higher than the space
temperature.
• The heating input on 1TB3 will drive the main changeover
coil IF conditions 1–4 are satisfied, but will always drive the
auxiliary coil valve (if present). Electric heat will be locked
out (where present) if hot water is available since SW4 will
be factory set to "ON" in these units.
32
EHl Ehfs
or to use the
Ehl
parameter but will in
parameter should be set to
Ai2b
Ai2M
Ai2M
parameter (in this
SW4 selects the electric heat lockout function, where we will
lock out the electric heat circuit based on either:
• The presence of hot water in the changeover coil section
Fprv
(if the parameter is set to
• Abnormal behavior of the fan/s (if the
FnSt
set to ).
• Or a combination of both the presence of hot water or
abnormal behavior of the fan/s (if the
EHFs
set to ).
• The preceding three examples depend on the inference of
the motor control board that hot water is present. In this
case, "hot" water is determined if:
– The temperature sensed is higher than the
parameter.
Ai2b
– The
parameter.
– The temperature is not in the dead-band between the
Ai2b
parameter and the
case, previous state will be retained).
– The input impedance of the thermistor circuit must be
set correctly (the
for CSTI units).
in
EHl
).
Fprv
Fprv
parameter is higher than the
Ai2M
parameter (in this
Aipu
parameter should be set to
parameter is
parameter is
Ai2b
Ai2M
in
UV-SVX005G-EN