Installation and Maintenance Manual

Startup
UNT-SVX07D-EN 89
Fan Mode Switch Operation
Off
Fan is turned off, two-position damper option spring-
returns closed.
Hi, Med, Lo
Fan runs continuously at the selected speed. The two-
position damper option opens to an adjustable
mechanical stop position.
Tracer ZN010 & ZN510 Operation
Off
Fan is off; control valves and fresh air damper option close.
Low air temperature detection option is still active.
Auto (Fan Cycling)
Fan and fresh air damper cycle with control valve option to
maintain setpoint temperature. In cooling mode, the fan
cycles from off to medium and in heating mode it cycles
from off to low. When no heating or cooling is required, the
fan is off and the fresh air damper option closes.
Low/Med/High (Continuous Fan)
Fan operates continuously while control valve option
cycles to maintain setpoint temperature. Fresh air damper
option is open.
Tracer ZN520 Operation
Off
Fan is off; control valve options and fresh air damper
options close. The low air temperature detection option is
still active.
Auto
Fan speed control in the auto setting allows the
modulating (3-wire floating point) or 2–position control
valve option and three-speed fan to work cooperatively to
meet precise capacity requirement, while minimizing fan
speed (motor/energy/acoustics ) and valve position (pump
energy, chilled water reset ). As the capacity requirement
increases at low fan speed, the water valve opens. When
the low fan speed capacity switch point is reached, the fan
switches to medium speed and the water valve repositions
to maintain an equivalent capacity. The reverse sequence
takes place with a decrease in required capacity.
Low/Med/High
The fan runs continuously at the selected speed and the
valve option will cycle to meet setpoint.
UC400 Controller Operation
Off
Fan is off; control valve options and fresh air damper
options close. The low air temperature detection option is
still active.
Auto
Fan speed control in the auto setting allows the
modulating (3-wire floating point) or 2-position control
valve option and 1-, 2-, 3- or variable-speed fan to work
cooperatively to meet precise capacity requirement, while
minimizing fan speed (motor/energy/acoustics) and valve
position (pump energy, chilled water reset). As the
capacity requirement increases, the water valve opens.
When the fan speed capacity switch points are reached,
the fan speed ramps up and the water valve repositions to
maintain an equivalent capacity. The reverse sequence
takes place with a decrease in required capacity.
Low/Med/High
The fan runs continuously at the selected speed and the
valve option will cycle to meet setpoint.
Sequence of Operation: Tracer
ZN010 and ZN510
Note: This section applies only to units with a Tracer
ZN010 or ZN510 controller.
Power-Up Sequence (Tracer ZN010 and ZN510)
When 24 Vac power is initially applied to the Tracer ZN010
or ZN510, the following sequence occurs:
1. All outputs are controlled off.
2. Tracer ZN010 and ZN510 reads all input values to
determine initial values.
3. The random start time (0-25 seconds) expires.
4. Normal operation begins.
Entering Water Temperature Sampling
Function (Tracer ZN010 and ZN510)
Both Tracer ZN010 and ZN510 use an entering water
temperature sampling function to test for the correct water
temperature for the unit operating mode. For all
applications not involving changeover, the water
temperature does not affect unit operation.
The entering water temperature sampling function opens
the main hydronic valve, waits no more than three minutes
to allow the water temperature to stabilize, then measures
the entering water temperature to see if the correct water
temperature is available.
The entering water must be five degrees or more above
the space temperature to allow hydronic heating and five
degrees or more below the space temperature to allow
hydronic cooling.
UNT-SVX07_-EN.book Page 89 Friday, April 27, 2012 9:40 AM