Application

ManualsBrandsSiemens ManualsBuilding automationDual Duct Variable Volume with Dedicated Ventilation Duct, Two Inlet Sensors, DCV and Hot Water Heat with Supply Temp Control (Template 14064)

Room Segment Functions

Device Control Functions HVAC

Siemens Industry, Inc.

Application Note

A6V11692055

Smart Infrastructure – Building Products

2019-04-01

Radiator Hot Water (RadHw11)

This application function operates a hot water valve for radiator(s) and supports

downdraft compensation. The main output is a modulating output for valve position.

Main features:

● Analog control of hot water radiator(s), configurable for power modulation

(SCR) or pulse width modulation

● Multiple radiator control (1...n)

● Downdraft compensation

● Heating available status

● Supply chain interface

Function

Radiator heating request (RadHReq) is received and processed into the output

signal for radiator valve position (RadVlvPos).

Hot water valve modulation: In response to heating demand, the heating valve is

modulated to control the room temperature at setpoint. It can also be 2-positioned

in response to external trigger(s) for special modes such as warm-up or cool down,

or safety conditions.

Note

This AF does not perform loop control; its main purpose is to execute commands.

Loop control processes (for this AF) are managed in the "room" AF(s) that

collaborate with this AF to command the end device.

Multiple radiator control: The radiator valve position collection object

(RadVlvPosCol) can reference and control multiple radiators.

Radiator valve position objects (RadVlvPos) are referenced by the radiator valve

position collection object (RadVlvPosCol); this collection object is a common node

for any / all RadVlvPos object(s). The value for RadVlvPos comes from

RadVlvPosVal.

Downdraft compensation: The downdraft compensation feature slows the sinking

cold air flow at large window surfaces and combats cold wall effect at cold

perimeter surfaces. This feature activates the radiator when the outside air

temperature drops below a configured value, raising the minimum temperature of

the radiator to a value higher than it would be otherwise.

Valve Position

Outside Air Temperature

Y1DndftElPos: 100%

X1DndftTOa: 23°F

Y2DndftElPos: 25%

X2DndftTOa: 50°F

Downdraft compensation is implemented using a linear reset function. The

following graphic shows factory default values for X,Y downdraft compensation

parameters.

Parameter EnDndft must be set to 1:Yes for downdraft compensation to function

(see Configuration).