Description of Operation

Auto Mode

Auto mode is provided so that the UVC can be set to automatically determine if heating or cooling is required. Auto mode is the default power-up UVC mode. Auto mode is made up of the Heat and Cool modes. When the UVC is set to auto mode, the UVC automatically determines which mode (Heat or Cool) to use.

Heat Mode (Super State)

When in Heat mode, the UVC will use auxiliary heat (if field provided and field connected to the unit) as needed to maintain the effective heating setpoint (see “Space Temperature Set Points” on page 26). The keypad/display or a network connection can be used to force the unit into the Heat mode. Additionally, the UVC when set to Auto mode can automatically force the unit into the Heat mode as needed. When the UVC is in Auto mode, it is “normal” for the UVC to “idle” in Heat mode when there is no need to switch to another mode.

The Heat mode super state consists of UVC states: Heat [5], Low Limit [E], and Cant Heat [B].

When the Heat mode super state becomes active, the UVC automatically determines which of the Heat Mode states to make active based upon the transitions for each state.

Figure 11: Heat mode super state diagram

Transition

 

 

 

 

 

 

 

 

 

 

 

point

 

 

 

 

 

 

 

 

 

 

UVC Mode = Heat

 

 

 

 

 

 

 

 

 

 

 

OR

 

 

 

 

 

 

 

 

 

 

 

UVC Mode = Auto AND

 

 

 

 

 

 

 

 

 

 

Space Warm

 

 

 

 

 

 

 

 

 

 

 

UVC Mode Heat AND

 

 

 

 

 

 

 

 

 

 

 

UVC Mode Auto

 

 

 

 

 

 

 

 

 

 

 

OR

 

 

 

 

 

Heat Mode

 

 

 

 

UVC Mode = Auto AND Space =

 

 

 

 

 

 

 

 

 

Warm AND Heat Pl = Sat Low

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Super State

 

 

 

 

 

Heat Available

 

 

Heat

 

 

 

Heat = Available

 

 

 

 

 

 

 

 

 

 

5

 

 

 

 

 

 

 

AND

 

 

 

 

 

 

 

Low Limit = Inactive

 

 

 

 

 

 

 

 

 

 

 

Heat Pl = Sat Hi

 

 

 

 

 

 

(2 minutes)

 

 

 

 

 

 

 

AND

Cant Heat

 

 

 

DAT<VCLL LLPl = Sat Lo

 

 

 

 

(2 minutes)

 

 

 

 

 

 

 

 

AND

 

B

 

 

 

 

 

 

 

 

 

 

 

 

DAT<(VCLL + 1.8F)

 

 

 

 

Heat = Available

 

 

 

 

 

 

 

 

 

 

 

 

 

 

AND

 

 

 

 

 

 

 

 

 

Low Limit = Inactive

 

 

 

 

 

Heat Available

Low Limit

E

Heat State (State 5)

The Heat state is the “normal” state during Heat mode. When the Heat state becomes active, the UVC will (within State) continually calculate the DATS (“Discharge Air Temperature Control” on page 29) required to maintain the effective heat setpoint (see “Space Temperature Set Points” on page 26). The calculated DATS will not be allowed to go above DAHL. The UVC will use auxiliary heat (if field provided and field connected to the unit) as needed to maintain the current DATS.The auxiliary heat binary output will be used as needed. The Heat Timer (3-minutes fixed) will begin counting. The CO2 demand controlled ventilation function will be active, if the unit is equipped for CO2 control (see “CO2 Demand Controlled Ventilation (optional)” on page 34), and the OA damper will be adjusted as needed to maintain the CO2 setpoint. The UVC will remain in this state until one of the transition out conditions become true, or until one of the super state transition out conditions becomes true.

McQuay OM 751

17

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Image 17
American Standard UV05 manual Auto Mode, Heat Mode Super State, Heat State State