Single-speed fan (Fan1Spd11)

This application function operates a single speed fan.

The fan binary command is calculated based on request signal for ventilation.

This application function is typically configured for fan coil unit. Can also support a series or parallel fan-powered VAV box, or a heat pump.

There is an optional binary input for the fan state.

This application function is NOT available for:
DXR2x09T

Required elements and how to configure them:

Element

I/O

Signal type

Fan1Spd "Single-speed fan"

On-board output, Fan speed

1-Stage Normally open

Function

The figure below shows BACnet objects associated with this application function. Primary signal flow is summarized as follows:

Basic function: Accept request signal from associated room controller and pass it through a device mode logic switch; Output the result as a command to the BACnet object that controls the device.

 

Command or request (or related)

Notification of condition or status, or availability

Device mode

Interlock (internal signal, not a BACnet object; see Interlocks section for additional information)

Interlocks

Room automation interlocks are internal signals that coordinate interaction between HVAC devices. They are not visible in ABT Site or web interface, but parameters associated with them are. See comment column for hints on parameters that affect interlock functionality.

Signal

Type

Direction

Description

Comment

AirFlCReq

Boolean

In

Air flow cooling request
▶ Initiates air flow (fan turns on) to satisfy air flow support request for cooling.

 

AirFlHReq

Boolean

In

Air flow heating request
▶ Initiates air flow (fan turns on) to satisfy air flow support request for heating.

 

AirFlDhuReq

Boolean

In

Air flow dehumidification request
▶ Initiates air flow (fan turns on) to satisfy dehumidification request from cooling coil.

 

AirFlVntReq

Boolean

In

Air flow ventilation request
▶ Initiates air flow (fan turns on) to satisfy ventilation request from OA damper.

 

AirFlHldC

Boolean

In

Air flow hold for cooling
▶ Interlock signal from DX cooling coil indicating the coil needs equipment protection air flow support. The fan is prevented from turning off for a period of time.

 

AirFlHldH

Boolean

In

Air flow hold for heating
▶ Interlock signal from electric heating coil indicating the coil needs equipment protection air flow support. The fan is prevented from turning off for a period of time.

 

AirFlSta

Boolean

Out

Air flow status
▶ Interlock signal that keeps the coil locked (or OA damper closed) at equipment protection priority (PrPrio = 5) unless the fan is running.

See Configuration section for parameters named "...AirFlSta".

AirFlVavReq

%

In

Air flow vav request
▶ In a fan-powered box (FPB) application, the VAV damper sends a proportional analog request signal (AirFlVavReq) requesting air flow, so that the box can meet an air flow / ventilation demand.

Fan-powered box application.

FanManOff

Boolean

Out

Fan manual off
▶ Interlock signal to turn off (at equipment protection priority) DX cooling coils and electric heating coils when the fan has been manually turned off (FanManOff = True). If fan device mode is set to 4:Manual speed, AND there is no demand for the fan to be on, then FanManOff will equal True.

 

Single speed fan operation

Parallel fan (FanSprtVav = "On request"):

 

Series fan (FanSprtVav = "Continuous on"):

 

Ventilation request - When FanDevMod is "Control mode" the fan is available for ventilation request (FanAvlVnt = Yes). When a ventilation request (FanVntReq) is greater than 4%, Fan1Spd = On. (Switch-off hysteresis to turn fan off is 2%.)

If device mode is not Control mode, FanVntReq has no effect.

Note
This feature ensures that the fan can provide a minimum ventilation air flow when there is little or no heating or cooling demand, such as in the "Neutral" zone during temperature sequencing.

 

Temperature sequencing

The figure shows temperature sequencing for heating and cooling:

 

 

Configuration

Objects

Description

Object

Type

Default value

Switch-off point for fan on VAV request
▶ For use with parallel fan powered box. This value represents the threshold level of air flow request coming from the VAV supply damper. When the cooling demand becomes large enough, the supply damper opens (to provide cooling air flow from the central AHU) and the parallel fan shuts off. See parameter FanSprtVav for additional information.

FanSwiOfAflVav

ACnfVal

50 [] 1), 2)

Hysteresis for fan on VAV request
▶ Amount below FanSwiOfAflVav, that the parallel fan will turn on.

FanHysAirFlVav

ACnfVal

10 [] 1), 2)

1) Value is taken as [m3/h] for pressure independent VAV control
2) Value is taken as [%] for pressure dependent VAV control

Parameters

Description

Parameter

Default value

Enable state input
▶ Must be set to 1:Yes when a binary fan status input is used.

0:No
1:Yes

EnStaIn

0:No

Interlocks

Switch-on delay for air volume flow state
▶ The amount of time after the fan is commanded on before the air flow state interlock signal becomes True. Until this time elapses, the interlock signal keeps the coil or OA damper locked / closed.

DlyOnAirFlSta

30 [s]

Fan support for variable air volume box
▶ For use with FPB (fan powered box). The configurable value must match the box type:

1:No (fan coil unit or heat pump)
2:On request (parallel fan powered VAV box)
3:Continuous on (series fan powered VAV box)

FanSprtVav

3:Continuous on

Enable fan operation before heating coil
▶ When this parameter is set to its default (No), the fan and coil activation is "parallel" (fan and coil operate together). Setting this parameter to Yes will enable the Fan to operate through its full speed range while the coil is either off or at minimum setting.

0:No
1:Yes

EnFanOpBfHcl

0:No

Interface

Interface

Description

Type

Ref.

Owned by

Fan1Spd

Single-speed fan

BO

◉

Room segment / Device

FanSta

Fan state
▶ When FanSta is enabled (parameter EnStaIn = Yes) and FanSta is True, AirFlSta (air volume flow state) turns on after the time delay in DlyOnAirFlSta.
0:Off
1:On

Note
For Fan1Spd11, if fan is switched on with no FanSta present, AirFlSta is still set to "on" by the output of DlyOnAirFlSta once time elapses.

BI

◉

Room segment / Device

Fan1SpdMan

Manual single-speed fan

0:Off
1:On

BPrcVal

●

-

FanDevMod

Fan device mode

1:Off
2:Control mode
3:Maximum speed
4:Manual speed

MPrcVal

●

-

FanCReq

Fan cooling request

ACalcVal

●

-

FanHReq

Fan heating request

ACalcVal

●

-

FanVntReq

Fan ventilation request

ACalcVal

●

-

FanAvlC

Fan available for cooling

0:No
1:Yes

BCalcVal

●

-

FanAvlH

Fan available for heating

0:No
1:Yes

BCalcVal

●

-

FanAvlVnt

Fan available for ventilation

0:No
1:Yes

BCalcVal

●

-

FanSwiOfAflVav

Switch-off point for fan on VAV request

ACnfVal

●

-

FanHysAirFlVav

Hysteresis for fan on VAV request

ACnfVal

●

-

Engineering and commissioning

See Configuration section for how to configure FanSwiOfAflVav and FanSprtVav with fan powered box.

Parameter EnStaIn must be set to 1:Yes if a binary fan status input is used.