
VAV-SVX01C-EN
49
Sequence of Operations
Heating
If the control action is edited to HEAT, the UCM controls the air valve as a heating source rather than
cooling. Electric reheat is available the supply air temperature (or auxiliary temperature) is below
70ºF. Local hot water reheat is always available to keep the zone above the heating set point. The
“Heating Minimum Flow Set Point” will set the minimum flow.
Flow Control Override
Flow control may be overridden by any of the following commands:
•
Drive Air Valve Fully Open. The air valve will be fully open and heat outputs disabled.
•
Drive Air Valve Fully Closed. The air valve is driven fully closed and heat outputs disabled.
•
Drive Air Valve to Minimum Flow. The air valve is driven to the minimum airflow set point. The
heat outputs remain operational.
•
Drive Air Valve to Maximum Flow. The air valve is driven to the maximum airflow set point. The
heat outputs remain operational.
Heat Control Override
Heat control can be disabled, locking out heat outputs.
Control Offset
Control offset may be enabled, which adjusts the edited cooling and heating set points.
Recalibrate (Reset)
The recalibrate function can be enabled. If enabled, the unit will perform a recalibration.
Fan-Powered Units
Parallel Fan-Powered Units
Occupied Units
Air valve control for parallel fan-powered units is the same as for single duct units.
The first heat output is utilized to control the fan. The remaining outputs are utilized to control heat.
Fan energization is a function of the “Parallel Fan Control Offset”. The parallel fan control can be
specified as an offset temperature in degrees above the heating set point or as a flow offset in CFM.
The fan will be energized above the fan control offset if reheat is required.
Parallel Fan Flow Type Control
If the fan control is based on flow, the unit fan will be energized whenever primary airflow is below
this set point. For this parallel fan configuration, the fan control point, if specified in a percentage
Table 10. Fan actuation schedule
FAN TYPE
OCCUPIED
UNOCCUPIED
Series
ON
OFF if valve closed AND reheat
off
Parallel based on
Temperature
Cool mode: ON if zone temp <heating
set point + fan offset fan 0.5°F
Heat mode: fan off unless reheat is on
Cool mode: OFF if zone
temp > heating set point + Heat mode:
fan off unless reheat is on
OFF unless local reheat is on
Parallel based on Flow
Cool mode: ON if flow < fan set point
OR if flow < active minimum flow set
point
Heat mode: fan off unless reheat is on
Cool mode: OFF if flow >
fan set point + 5% AND
flow > active minimum
flow set point
Heat mode: fan off unless reheat is on
OFF unless local reheat is on
Содержание VAV-UCM 4.2
Страница 1: ...May 2010 VAV SVX01C EN Installation Operation Maintenance VAV UCM 4 2...
Страница 81: ...VAV SVX01C EN 81 Troubleshooting Figure 46 Single duct with single phase voltage electric heat...
Страница 82: ...82 VAV SVX01C EN Troubleshooting Figure 47 Single duct with three phase voltage electric heat...
Страница 83: ...VAV SVX01C EN 83 Troubleshooting Figure 48 SCR PSC fan powered with single phase voltage electric heat...
Страница 84: ...84 VAV SVX01C EN Troubleshooting Figure 49 SCR PSC fan powered with three phase voltage electric heat...
Страница 85: ...VAV SVX01C EN 85 Troubleshooting Figure 50 ECM fan powered with single phase voltage electric heat...
Страница 86: ...86 VAV SVX01C EN Troubleshooting Figure 51 ECM fan powered with three phase voltage electric heat...