1

DDC Controls and Software

for the HVACR Lab

by Greg Jourdan

Wenatchee Valley College

Las Vegas, Nevada

March 15-16th

, 2010

2:30-4 PM

DDC Controls and Software for the HVAC Lab

Agenda

1. Types and Level of Automation

2. HVAC DDC Control Principles

3. Open Protocol Control Principles

4. DDC Architecture

5. Examples of DDC Software Programs

6. Typical DDC Control Systems and Applications

7. Present and Future Trends in DDC Controls

8. Getting DDC Equipment in your Schools

DDC Controls Quiz

1. T F DDC and PLC’s are basically the same control devices.

2. T F There are 3 key components of any DDC controls system.

3. T F BACNet, Lon, and Tridium are Open Software DDC Integration Tools

4. T F The thermistor is linear like the RTD.

5. T F The Boolean Point is used for converting temperature sensors into useful information.

The Various Levels of DDC and

Automation

• Residential and Home Automation

– Smart Homes, not widely adopted with HVAC Manufacturer’s Equipment

– Smart HVAC Systems, ie. Carrier, Nordyn

• Commercial

– DDC is Designed for Commercial Buildings

– Multiple Vendors

• Industrial

– PLC’s, SCADA, Ladder Logic, Costly $$$

Residential and Home Automation

Commercial DDC Automation

Present DDC Control Vendors and

Merger Corporations

Schneider

Industrial Automation

Evolution of Controls and DDC

PC Based DDC Control System

Field

Panel

1

Field

Panel

2

Field

Panel

3

Trunk / Network

Cable

LAN Devices LAN Devices

Modern DDC Building Controls Utilize

a Four Level Architecture

Sensor Level

Field Controller Level

Integration Level

Management Level

The Purpose of any Temperature

Control System

• Control systems are the “brains” of HVAC equipment to maintain human comfort. Pictured below is an AHU that serves only one zone. This type of AHU is called a single zone AHU. In the example, a temperature sensor (stat) sends a signal to a control panel, which sends a signal to a valve.

Three (3) Key Components of any

Control System Include:

DDC Terminology

Set Point and Offset

Set point is the desired condition of a variable that is to be maintained, such as temperature. In the example below, 75 degrees F. is the room temperature set point. Offset is the amount of difference between control point and set point in a proportional control system. In the example below, the offset is approximately 4°F.

DDC Terminology

Control Point

• The Control Point is the actual temperature being sensed. The Control Point (temperature) may not be on the set point, but instead may be above or below it. Simply stated, set point is what you want, while control point is what you get.

DDC Terminology

Throttling Range

• System Throttling Range (STR) is the change in the measured variable (i.e. temperature) that causes the controlled device to travel from one end of its stroke to the other.

•Two Position

•Floating Action

•Proportional Action

•PI

•PID

The DDC Control Cycle and

Control Action Can be Very Accurate

Control Cycle Graph

Two Position

(Old School-Not Accurate)

Two Position control action chart (heating action shown)

Floating Action Control

Floating Control Action

Proportional Action

Proportional Control Action

Proportional with Integral Control

(PI)

Proportional Plus Integral (PI) Control Action

PID-Proportional

Plus Integral & Derivative

Proportional Plus Integral Plus Derivative (PID) control action

• Boolean - Represents a binary value with only two states, such as "Off" or "On."

• Numeric - Represents an analog value such as a temperature, level, rate or similar floating point number, or a varying count (integer).

• Enum - Represents an enumerated state (more than two), such as a multi-speed fan with states "Off," "Slow," and "Fast." Enums are often called multi-states or discretes.

• String - A string of one or more ASCII characters and often (if alpha-numeric) with some literal meaning.

Four Types of Point Data Categories

Control Points for the DDC System

29

Eight Types of Control Points

Control Points for the DDC

Boolean Numeric Enumerated String

BooleanPoint

•A read only point

−Facets

−Proxy Extension

−Out

NumericPoint

• A read only point

−Facets

−Proxy Extension

−Out

EnumPoint

• A read only point

−Facets

−Proxy Extension

−Out

StringPoint

• A read only point

−Facets

−Proxy Extension

−Out

BooleanWritable

• Extended to include

−Priority controls

−Fallback property

−Override expiration

−7 Commands

−On & Off timers

NumericWritable

• Extended to include

−Priority controls

−Fallback property

−Override expiration

−5 Commands

EnumWritable

• Extended to include

−Priority controls

−Fallback property

−Override expiration

−5 Commands

StringWritable

• Extended to include

−Priority controls

−Fallback property

−Override expiration

−5 Commands

Sensors

• A sensor monitors and measures a variable. The HVAC variables are temperature, humidity, flow, and pressure. Different types of signals are produced by different types of sensors. They include:

–Electric Sensors

–Pneumatic Sensors

–Electronic Sensors

Examples of a sensor is shown here. While it may appear to be a thermostat, it is a remote sensor with a remote set point dial. The controller is in another location.

Electronic Sensors Include:

• Resistance sensors are Resistance Temperature Devices (RTDs), and are used in measuring temperature.

• Voltage sensors could be used for temperature, humidity and pressure.

• Current sensors could be used for temperature, humidity, and pressure. The typical current range is 4 to 20 mA (milliamps).

Temperatures Sensors Can be either

Thermocouple, RTD, or Thermistor.

This Chart Compares the Advantages and

Disadvantages.

Modern HVAC DDC Sensors Include

• Humidity and Temperature Transmitters

• CO2 for Indoor Air Quality (IAQ) Utilizing Demand Ventilation

• Power Meters

• Branch Circuit Monitors

• Energy Meters

Controllers Can Include:Electric Controls Pneumatic Controls

Electronic Controls

DDC

Controls

Controllers Principles

The Controller Receives the Input

and Processes an Output

The DDC Controller Has 3 Functions

1. Receives the Input From the Sensor

2. Performs a Logic Function

3. Processes an Output

Basic DDC-Electronic Control System

Direct Digital Control System

DUCT

SPACE

DISCHARGE

SENSORS

DIGITAL COMPUTER

With INTERFACE

HARDWARE

ELECTRIC

MOTOR

DAMPER

ELECTRIC

OPERATOR

VALVE

VALVE

PNEUMATIC

OPERATOR

E-P

TRANSDUCER

FINAL CONTROL

ELEMENTS

Controlled Devices

Dampers and Valves

Automatic Control

Typical Multiblade Dampers

Typical Three-Way Mixing

and Diverting Valves

Typical Single - and Double-Seated

Two-Way Valves

Controlled Devices

2-Way & 3-Way Control Valves

•Fully Electronic

•3-Way Control Valves

•Not commonly used

•2-Way Control Valves

•Used with DP sensors and VSD pump

systems

•Pressure Independent Characterized

Control Valves™ (PICCV)

•No Cv required, reduced pumping

costs, higher efficiency, easy to

balance

DDC Control Systems -

Use Control Valves That Are

Controlled Devices

Economizer Damper Actuators

Direct Connect Actuator Damper Connected to Actuator

Via Shaft and Coupling

Damper Actuators are Controlled by

Either a Voltage (2-10vdc) or Current

(4-20ma) Signal from the Controller

Courtesy Belimo

•Vary Frequency of Motor

•Often Called VSDs or VFDs

•Used with Any Variable Motor Speed

Control Application

Electronic ASDs, VFD’sAdjustable Speed Drives

Adjustable Speed Drives Turn AC to DC and Back to AC (Pulsed PWM)

Variable Frequency Drives (VFD’s) are

Becoming Standard Equipment On:

• Towers

• VAV Fans

• Pumps

• Chillers

Example of DDC Controls

Example of DDC Control

Heating Coil Control With Reset

Example of DDC Control

Converter Control With Reset

The Westin Building: Hydronic System VSD’s match calculated Building Demand to

Cooling Tower tonnage

Variable Speed Pumps are Used in

HVAC Projects for Energy Conservation

VSD Drives on Fans to Maintain Static

Pressure for Energy Conservation

http://www.mmtmagazine.org/page/indexa916.html?id=44

Many Factory Built-Up AHU’s

Are VAV with DDC Controls

Modern Control Systems Tie All

Building Systems Together Via a

Standardized Networks (TCP/IP, BACnet, LON)

HVAC

Life Safety Systems

Lighting

Security

Chillers

Boilers

Building Switchgear

Current automation systems allow communications with multiple vendors

■ Fire alarm, security

■ Lighting, fan units

■ PLCs (Programmable Logic

Controllers)

■ Boilers and chillers

DDC Software is Integrated

into the Building Systems

•BACnet, Developed by ASHRAE

•True, Non-proprietary, Open Protocol

(Industry Standardized)

•Multiple Vendor Controllers

BACnet Software Standard Protocol

BACnet Connectivity

Third Party Interface

vs. BACNet Gateway

LonWorks Platform (Open Protocol)

LonTalk and the Neuron Chip

* Units sold and revenue for BACnet, LonWorks, and proprietary systems in the building automation industry, 1998-2008

(Source: Frost & Sullivan, North American Building Protocol Analysis, 2001 #A143-19)

82178648947907472008

68461231717581832001

60443110588441451998

Pro-

prietary

LonBACnetPro-

prietary

LonBACnet

Revenue

(mill $)

Units

(1000s)

BACnet is the Preferred and Fastest

Growing Network Standard

DDC Networks Have Lot of Connections

And Don’t Always Communicate between the

Various Vendors

Application A Application B Application C

Niagara Normalizes All Systems

BACNet or LON Network

Application A Application B Application C

DDC Control Systems –

Schematics are done on AutoCAD

•Drawings are sent via email

•As Built Modifications are easy to change

Example of DDC AutoCAD Boiler Controls

Typical DDC AutoCAD-Example Schematic

Actuator

SensorsController

Typical DDC Software Controls on

Factory AHU’s Economizer Example

Actuator

ControllerSensors

Sensors

Actuator

Controller

Typical DDC Software Controls on Factory

AHU’s Economizer Example

Typical Controls on Factory AHU’s

Example of Program for Siemens Controls

Typical Controls on Factory

AHU’s- Example of Program for

Siemens Controls

Typical DDC Controls AHU’s-Example

of Automated Logix Graphics Display

Present and Future DDC Systems

Are Using

Smart Card Access

• Employee ID Card

• Physical Access Badge

• Remote Access Token

• Combines function into a single smart card on a USB stick

Present and Future Control

Systems are Using

• PDA’s by the building operators are used as diagnostic and maintenance tools.

75

Present and Future Control Systems

Will Be Able to Do Anything Money

Will Buy Including:

• Using Cloud Height Ceilometers

• Owners can know the weather without going outside. Performance and reliability in all weather conditions up to 25,000 feet

• GPS Tracking Systems on each individual in the Building

Present and Future Controls are

Using Wireless Mesh Networks

Wireless Networks Include:

Wibree

Bluetooth

ZigBee

Present and Future Controls are

Using Wireless Power Meters

Talking

ThermostatsTelephone

Thermostats

Present and Future DDC Controls

are Smart at the Field Level

Smart Air

Velocity Sensors

Present and Future DDC Controls

are Smart and on the Internet WEB

Present and Future DDC Building

Control Systems Will

Control Individual Lighting

Monitor Each Tenants

Total KwH Power

Control RH and CO2

Provide Customers

Options to Control

Individual Space or

Cubicle Areas via the Web

•Door Lock ID tags to always tell management where

you are in the building.

•Radio frequency ID systems which allow you to track

building inventory and manage information with

reliability, even in harsh industrial environments.

Present and Future DDC Control

Systems Can Use

DDC Challenges and Obstacles for

HVAC Instructors and Students

• DDC Building Systems are becoming more complex.

• Information Tech (IT) Departments need to be involved in maintenance of building controls

• Future trends and demands for skilled labor is creating shortages (not enough people entering blue collar trades)

DDC HVAC Controls

Changes and Challenges

Building Controls are Evolving to become:

Totally Integrated

Modern Sensors and Instrumentation Devices will be Adopted

Maintaining Building Efficiencies and Comfort at Minimum Costs will be more complex.

Challenges and Obstacles will be a continued shortage of skilled labor.

Getting Started with DDC at your

HVAC School

• Network with Industry

• Work as Summer Interns

• Develop or Buy Updated Curriculum

Getting Started with DDC at your

HVAC School

• Get the DDC Equipment

• Donated is Ok, New is Better

• Start Writing Grants

Answers to DDC Controls Quiz

6. T F HVAC Systems cost over 35% of

the energy in the typical building.

7. T F The minimum CFM requirements for a

home is based on the number of people.

8. T F According to EPA and WHO, Americans

spend approximately 90% of their time

indoors.

9. T F High return air CO2 above 1000 ppm is

an indication of IAQ problems.

10.T F Vents, chimneys, flues must be at least

10’ from outside air intakes.

1. T F DDC and PLC’s are basically the same control devices.

2. T F There are 3 key components of any DDC controls system.

3. T F BACNet, Lon, and Tridium are Open Software DDC Integration Tools

4. T F The thermistor is linear like the RTD.

5. T F The Boolean Point is used for converting temperature sensors into useful information.

87

DDC Controls and Software

for the HVACR Lab

by Greg Jourdan

Wenatchee Valley College

Any Questions?

Thank You