42
BAS-SVX62E-EN
Calibration, Operation Modes, and Control
On/Off Electric Reheat
The Airflow Setpoint Minimum Local Heat is enforced during reheat.
•
Stage 1;
energizes when the space temperature falls below the active heating setpoint and
minimum airflow requirements are met. When the zone temperature rises above the active
heating setpoint by 0.5°F (0.28°C), stage 1 is de-energized.
•
Stage 2;
energizes when the space temperature is 1°F (0.56°C) or more below the active
heating setpoint, and is de-energized when the space temperature is 0.5°F (0.28°C) below the
active heating setpoint.
•
Stage 3;
energizes when the zone temperature is 2°F (1.11°C) or more below the active heating
setpoint, and de-energizes when the space temperature is 1.5°F (0.83°C) below the active
heating setpoint.
When reheat is de-energized, the cooling Airflow Minimum Setpoint is enforced. Refer to
and
Hot Water Heat
Two types of control of hydronic heat are supported:
•
ON/OFF
Refer to on/off electric heat for operation. The main difference with ON/OFF hot water heating
is the control of a two position hot water valve instead of the contactor energizing an electric
heat strip. Refer to
and
•
Modulating
Proportional hot water reheat uses 3-wire, floating-point-actuator technology. It is enabled if
there is no valid supply air temperature and disabled if the supply air temperature is greater
than the configured reheat enable setpoint.
When the space requires cooling, the air valve modulates between Airflow Setpoint Maximum
and Airflow Setpoint Minimum, to maintain space temperature at the active cooling setpoint;
and the water valve is closed. When the cooling load has decreased to the point where the air
valve has reached Airflow Setpoint Minimum, space temperature is allowed to drift downward,
in the deadband between the active cooling setpoint and active heating setpoint.
When the space temperature drops below the active heating setpoint, the air valve opens to the
Airflow Setpoint Reset Minimum Local Heat and the reheat valve modulates to maintain space
temperature at the active heating setpoint. Control of the water valve uses a separate
proportional plus integral control loop, and its position is dependent on the degree that the
Fan and On/Off
hot water (1 to 2
stages)
Not
applicable
Parallel fan
Local thermostatic:
• On: Zt < HSP
• Off: Zt
HSP + 0.5°F (0.28°C)
Local thermostatic:
• On: Zt < HSP - 1°F (0.56°C)
• Off: Zt
HSP - 0.5°F (0.28°C)
Not applicable
Total capacity is limited by
communicated supply heat control.
Total capacity is limited by
communicated supply heat
control.
Not applicable
Fan and
Modulating hot
water
Not
applicable
Parallel fan
• Local PI capacity loop.
• Modulating valve capacity = Total
capacity.
• Valve drive incrementally open/
closed.
• Total capacity limited by
communicated supply heat
control.
• Local PI capacity loop.
• Modulating valve capacity = Total capacity.
• Valve drive incrementally open/closed.
• Total capacity limited by communicated supply heat control.
Table 10. Local Heat Only With Parallel Fan Present (continued)
Configuration
Method of Control
Local
Remote Fan
Stage 1
Stage 2
Stage 3