ddc technical manual

Table of Contents

Control of Supply Air Temperature ....................................................................................................... 1

Control of Humidity ............................................................................................................................. 3

Space or Room Air Control ................................................................................................................... 5

Control of Duct Static Pressure .............................................................................................................. 7

Outside Air Temperature Lockout......................................................................................................... 9

Temperature Setpoint Reset ................................................................................................................ 10

Outside Air Economizer ...................................................................................................................... 11

Optimal Start ...................................................................................................................................... 13

Filter Clean/Dirty Pickup Installation .................................................................................................. 14

Duct Static Pressure Pickup Installation ............................................................................................... 15

Typical Averaging Element Installation ............................................................................................... 16

Pressure Device Mounting Detail ......................................................................................................... 17

Typical Pipe Strap-on Element Installation .......................................................................................... 18

Typical Immersion Type Element Installation ...................................................................................... 19

Typical Outside Air Temperature Element Installation ........................................................................ 20

Typical Space Temperature Element Installation ................................................................................. 21

Typical Space Temperature/Humidity Element Installation ................................................................. 22

Typical Duct High/Low Limit Switch Installation ................................................................................ 23

Typical Current Sensor Installation ..................................................................................................... 24

Typical KW/KWH Transducer ............................................................................................................ 25

Typical Belimo Actuator Wiring Schematic ......................................................................................... 26

Typical Control Enclosure................................................................................................................... 27

Tips for Bending Conduit for Stub-ups ................................................................................................ 28

Valve Piping Illustrations .................................................................................................................... 30

Drill and Screw Size Chart ................................................................................................................... 32

Sensor Networks ................................................................................................................................. 33

Reference Data .................................................................................................................................... 34

Corey Simon, Project Engineer Computrols, Inc.

826 Lafayette Street New Orleans, Louisiana 70113 Phone: 504.529-1413 Fax 504.529.1463 www.computrols.com

Control of Supply Air Temperature System Flow Diagram

Avoid using spring return actuators on control valves for wetted coil applications. When selecting

Sequence of Operation The DDC controller uses a temperature sensor mounted in the supply air duct to modulate control valves or mixing dampers to maintain a supply air temperature setpoint. In most systems that employ a heating and cooling coil, the hot water valve and the chilled water valve should be modulated in sequence. When the supply air temperature falls below setpoint, the hot water valve begins to modulate open and consequently, the cooling valve begins to modulate closed. If the supply air temperature continues to fall below the setpoint, the heating valve will open fully and the cooling valve will close completely. When the supply air temperature rises above setpoint, the hot water valve begins to modulate closed and consequently, the cooling valve begins to modulate open. If the supply air temperature continues to rise above the setpoint, the heating valve will fully close and the cooling valve will open completely. A temperature sensor located in the mixed air stream (between the unit filters and the coils) is used to provide mixed air low limit control. When the temperature sensed by this element falls below the setpoint, the outside air damper fully closes, the return air damper fully opens, the exhaust air damper closes to a minimum position, and the valves on all coils will fully open. This sequence should always be used on systems with wetted coils. When the unit fan is turned off, the outside air damper fully closes, the return air damper fully opens, the exhaust air damper fully closes, and all control valves return to their normal positions. Design Considerations Control Valves

two-way valves for control of wetted coils: For hot water coils, have the valve configured in the normally open position. For chilled water coils, have the valve configured in the normally closed position.

When selecting three-way valves for control of wetted coils:

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For hot water coils, have the valve piped such that when the valve is in the normal position, the water flows through the coil. For chilled water coils, have the valve piped such that when the valve is in the normal position, the water bypasses the coil. It is recommended that mixing valves be used in all three-way applications unless otherwise specified.

Always use opposed blade dampers in control applications that require the mixing of air. Opposed blade dampers cause turbulence in the air flowing through them. This turbulence causes more complete

for smoke dampers and exhaust air dampers. Use spring return actuators for all dampers. Mixing dampers should be properly sized to provide good control. Improper sizing will result in the stratification of air streams of different temperatures.

This device should be positioned across the face of the heating coil (if the heating coil is before the cooling coil) or across the face of the preheat coil if one is employed. The capillary element must serpentine horizontally across the face of the coil. If the capillary element is not arranged in this manner, the device will not function properly. It is recommended that a low limit switch with a set of normally closed contacts and a set of normally open set of contacts be used. The normally closed contacts

Always use an averaging type element when access to the mixed air plenum is possible. If the mechanical room is used as the mixed air plenum, place the averaging element in front of the units filter bank. Do not attach the averaging element to the filter bank. If access is a problem, then appropriately place a duct-mounted temperature probe in a position that is most representative of the temperature of the mixed air stream. Try to avoid positions near bends in the duct.

Use a duct-mounted probe placed far enough down the supply air duct so that the supply air stream has been properly mixed.

Use separate analog outputs for the chilled water and hot water valves. The PID loops for the chilled-water valve and the hot-water valve should be configured as direct acting. In order for this configuration

control valves to the normal position when the fan is off. Never cut power to a proportional spring return actuator to return the actuator to the normal position. Always use the software to return the spring return actuator to the normal position. The spring return feature is incorporated to ensure that the controlled device returns to the fail-safe position upon loss of control power.

Caution - Do not pipe globe valves that are designed for mixing applications for diverting service. The fluid flow will cause a hammering effect and severe noise and damage will follow.

Mixing Dampers

mixing of the air streams and reduces the risk of freezing coils due to air stratification. Use opposed blade dampers for outside air dampers and return air dampers. Parallel blade dampers should be used

Low Limit Switch or Freezestat

should be wired directly into the fans starter circuit to de-energize the fan when the setpoint is reached. The normally open set of contacts should be wired to one of the DDC controllers binary input points. Always use a manual reset low limit device.

Mixed Air Sensor

Supply Air Sensor

Software Configuration

to be used, the guidelines in item #1 Control Valves must be adhered to completely. Always return all

Note: These guidelines do not apply to spring return on-off type actuators.

2

Control of Humidity

System Flow Diagram

Sequence of Operation The DDC controller uses a humidity sensor mounted in the return air duct or the space to modulate control valves or to stage electronic humidity control equipment to maintain a relative humidity setpoint. In most systems that employ humidity control equipment, the controlled equipment will usually include a cooling coil used for dehumidification and/or either a steam valve humidifier or an electronic humidifier. When the return air or space-relative humidity rises above setpoint, the chilled water valve fully opens. As a result of this action, the reheat devices, whether a duct-mounted reheat coil or a space-mounted radiant heater, temper the cooler air produced by the fully-opened cooling coil to maintain either the supply air temperature setpoint or the space temperature setpoint. Dehumidification is accomplished by cooling the air below the dew point causing the air to dry. When the return air or space relative humidity falls below setpoint, the humidifier steam valve begins to modulate open or the electric humidifier begins to stage on. When both dehumidification and humidification equipment are employed, the supply air humidity sensor provides humidity high limit control. This high limit overrides the humidifiers steam valve to the closed position or the electric humidifier off when the humidity high limit setpoint is reached. When the unit fan is turned off, the steam valve will close or the electric humidifier will be turned off and all other control valves will return to their normal position. Design Considerations Control Valves Avoid using spring-return actuators on control valves for wetted coil applications. When selecting two-way valves for control of wetted coils:

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For hot water coils, have the valve configured in the normally open position. For chilled water coils, have the valve configured in the normally closed position.


For hot water coils, have the valve piped such that when the valve is in the normal position, the water flows through the coil. For chilled water coils, have the valve piped such that when the valve is in the normal position, the water bypasses the coil. It is recommended that mixing valves be used in all three-way applications unless otherwise specified. Caution - Do not pipe globe valves that are designed for mixing applications for diverting service. The fluid flow will cause a hammering effect and severe noise and damage will result.

For space-mounted locations, avoid mounting the sensor near direct sources of cool or hot air. Avoid mounting near appliances that release steam or condensation such as coffee makers, stoves, or ovens.

Use separate analog outputs for the chilled water, hot water, and steam valves. The PID loops for the chilled water valve and the hot water valve should be configured as direct acting. In order for this configuration to be used, the guidelines in item #1 Control Valves must be adhered to completely. Always return all control valves to the normal position when the fan is off. Never cut power to a proportional spring return actuator to return the actuator to the normal position. Always use the software to return the spring return actuator to the normal position. For proportional spring return actuators that incorporate a phase cut feature, this may be used in conjunction with the software to return the proportional actuator to the normal position. The spring-return feature is incorporated to ensure that the controlled device returns to the fail-safe position upon loss of control power. Note: These guidelines do not pertain to spring-return on-off type actuators.

Humidity Sensor


4

Space or Room Air Control System Flow Diagram

Sequence of Operation The DDC controller uses a temperature sensor mounted in the supply air duct to modulate control valves or mixing dampers to maintain a supply air temperature setpoint. In most systems that employ a heating and cooling coil, the hot water valve and the chilled water valve should be modulated in sequence. When the supply air temperature falls below setpoint, the hot water valve begins to modulate open and consequently, the cooling valve begins to modulate closed. If the supply air temperature continues to fall below the setpoint, the heating valve will open fully and the cooling valve will close completely. When the supply air temperature rises above setpoint, the hot water valve begins to modulate closed and consequently, the cooling valve begins to modulate open. If the supply air temperature continues to rise above the setpoint, the heating valve will fully close and the cooling valve will open completely. A temperature sensor located in the mixed air stream (between the unit filters and the coils) is used to provide mixed air low-limit control. When the temperature sensed by this element falls below the setpoint, the outside air damper fully closes, the return air damper fully opens, the exhaust air damper closes to a minimum position, and the valves on all coils will fully open. This sequence should always be used on systems with wetted coils. When the unit fan is turned off, the outside air damper fully closes, the return air damper fully opens, the exhaust air damper fully closes, and all control valves return to their normal positions. Design Considerations Control Valves Avoid using spring return actuators on control valves for wetted coil applications. When selecting two-way valves for control of wetted coils:

For hot water coils, have the valve configured in the normally open position. For chilled water coils, have the valve configured in the normally closed position.


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For hot water coils, have the valve piped such that when the valve is in the normal position, the water flows through the coil. For chilled water coils, have the valve piped such that when the valve is in the normal position, the water bypasses the coil. It is recommended that mixing valves be used in all three-way applications unless otherwise specified. Caution - Do not pipe globe valves that are designed for mixing applications for diverting service. The fluid flow will cause a hammering effect and severe noise and damage will result.

Mixing Dampers Always use opposed blade dampers in control applications that require the mixing of air. Opposed blade dampers cause turbulence in the air flowing through them. This turbulence causes more complete mixing of the air streams and reduces the risk of freezing coils due to air stratification. Use opposed blade dampers for outside air dampers and return air dampers. Parallel blade dampers should be used for smoke dampers and exhaust air dampers. Use spring return actuators for all dampers. Mixing dampers should be properly sized to provide good control. Improper sizing will result in the stratification of air streams of different temperatures. Low Limit Switch or Freezestat This device should be positioned across the face of the heating coil (if the heating coil is before the cooling coil) or across the face of the preheat coil if one is employed. The capillary element must serpentine horizontally across the face of the coil. If the capillary element is not arranged in this manner, the device will not function properly. It is recommended that a low limit switch with a set of normally closed contacts and a set of normally open contacts be used. The normally closed contacts should be wired directly into the fans starter circuit to de-energize the fan when the setpoint is reached. The normally open set of contacts should be wired to one of the DDC controllers binary input points. Always use a manual reset low-limit device.

Mixed Air Sensor Always use an averaging type element when access to the mixed air plenum is possible. If the mechanical room is used as the mixed air plenum, place the averaging element in front of the units filter bank. Do not attach the averaging element to the filter bank. If access is a problem, then appropriately place a duct-mounted temperature probe in a position that is most representative of the temperature of the mixed air stream. Try to avoid positions near bends in the duct.

Supply Air Sensor: Use a duct-mounted probe placed far enough down the supply air duct so that the supply air stream has been properly mixed.

Space Sensor: For space-mounted locations, avoid mounting the sensor near direct sources of cool or hot air. Avoid mounting near appliances that release steam or condensation such as coffee makers, stoves, or ovens.

Software Configuration Use separate analog outputs for the chilled water and hot water valves. The PID loops for the chilled water valve and the hot water valve should be configured as direct acting. In order for this configuration to be used, the guidelines in item #1 Control Valves must be adhered to completely. Always return all control valves to the normal position when the fan is off. Never cut power to a proportional spring return actuator to return the actuator to the normal position. Always use the software to return the spring return actuator to the normal position. The spring return feature is incorporated to ensure that the controlled device returns to the fail-safe position upon loss of control power. Note: These guidelines do not apply to spring return on-off type actuators.

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7

Control of Duct Static Pressure

System Flow Diagram

Supply Fan Variable Frequency Drive Control

Supply Fan Inlet Vane Control

Supply Duct Dump Damper Control

Sequence of Operation The DDC controller uses a differential pressure transmitter connected to a static pressure sensing tip mounted in the supply air duct just before the last VAV box on the duct branch to modulate a VFD, inlet vanes, or a dump damper to maintain a supply air static pressure setpoint. When the supply air static pressure falls below setpoint, the VFD, inlet vanes, or dump damper begins to modulate open. If the supply air static pressure continues to fall below the setpoint, the VFD, inlet vanes, or dump damper will continue to open. When the supply air static pressure rises above setpoint, the VFD, inlet vanes, or dump damper begins to modulate closed. If the supply air static pressure continues to fall below the setpoint, the VFD, inlet vanes, or dump damper will continue to close. A duct-mounted high-static pressure safety switch is mounted in the supply air stream to prevent over-pressurization of the duct. This switch must be wired into the safety circuit of the units VFD or motor starter. When the unit fan is turned off, the outside air damper fully closes, the return air damper fully opens, the exhaust air damper fully closes, and all control valves return to their normal positions. Design Considerations

Choose a device with a maximum range that most closely matches the units maximum static pressure output. For most systems, a 0

section of this manual for proper mounting. Static Pressure High Limit This device should be positioned in the supply air stream. It is recommended that a manual-reset static pressure high-limit switch with a set of normally closed contacts and a set of normally open contacts be used. The normally closed contacts should be wired directly into the fans motor starter or VFDs safety circuit to de-energize the fan when the setpoint is reached. The normally open set of contacts should be wired to one of the DDC controllers binary input points. Always use a manual reset low-limit device. Software Configuration The PID loops for the VFD, inlet vanes, or dump damper should be configured as reverse acting. For VFD applications, set the acceleration and deceleration times on the VFD to 120 seconds. This will ensure that the VFD does not quickly ramp up or down in response to small changes in the static pressure.

Differential Pressure Transmitters

3 W.C. device is adequate. Mount this device as close to the static pressure sensing tip as possible to avoid long pneumatic tubing runs.

Static Pressure Sensing Tip See the Duct Static Pressure Pickup Installation

8

Outside Air Temperature Lockout System Flow Diagram

Sequence of Operation The DDC controller uses a temperature sensor mounted in the outside air to lockout the mechanical means of cooling or heating. When the outside air temperature falls below the lockout setpoint for cooling, the DDC system will provide a signal to turn off the mechanical cooling means. When the outside air temperature rises above the lockout setpoint for heating, the DDC system will provide a signal to turn off the mechanical heating means. Design Considerations

This sensor should be mounted on the wall with the northernmost exposure. If mounting the sensor on an outside wall is not possible, then mount a probe-type sensor in the outside air duct. Mounting the sensor in the duct has one drawback: in this location, the sensor is subject to reading stagnant air when the outside air damper is closed. Use a weatherproof housing with a sun shield and a windshield to reduce the possibility of false readings. It is recommended that a humidity element be incorporated in the housing for other control functions.

This control strategy should be used to lockout mechanical heating or cooling equipment such as chillers, boilers, or d

Outside Air Temperature Sensor


irect expansion (DX) units and should not be used to close heating or cooling valves. Do not confuse this control strategy with the low-limit control strategies found in earlier sections of this manual. When mechanical equipment is turned off using the outside air temperature lockout strategy, it is generally good practice to signal all control valves and/or on-off type equipment associated with the respective system to return to the normal position. Always incorporate at least a two-degree temperature differential when using this control strategy to avoid cycling the equipment too frequently.

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Temperature Setpoint Reset System Flow Diagram

Sequence of Operation

Design Considerations

This sensor should be mounted in the return air duct. Use a probe-type sensor for the installation.

To implement this control strategy, program the system to use a similar reference table as shown below:

The DDC controller uses a temperature sensor mounted in the return air duct or the space to reset the setpoint of the supply air temperature. In order to accomplish this, the supply air temperature is varied based on the readings from the return air or space sensor. Once the corresponding supply air temperature setpoint has been determined, supply air temperature control uses the setpoint to maintain the supply air temperature.

Return Air Temperature Sensor


Return Air or Space Temperature

(OF)

Supply Air Temperature Reset

Setpoint (OF) 69O 60O 70O 58O 72O 55O 74O 54O 76O 53O

Keep in mind that when wetted coils are employed as the heating and cooling means to control the supply air temperature, the lowest possible supply air temperature that is attainable for discharge is nominally about 52O F. If direct expansion (DX) coils are employed, the discharge air temperature can be reduced to as low as 42O F.

10

Outside Air Economizer System Flow Diagram

Sequence of Operation The outside air economizer strategy is employed so that the outside air or the return air can be used to lessen the load experienced by the cooling coil. This in turn reduces the need for mechanical cooling from the related equipment providing energy savings. There are two types of economizer strategies:

The DDC controller uses a combination temperature and humidity sensor mounted in both the outside air and return air ducts to close the outside air damper to a minimum position when the outside air enthalpy exceeds the return air enthalpy. Enthalpy, in a simplified sense, is nothing more than the total heat capacity of the air. In humid climates, the enthalpy (or total heat) of the outside air may be greater than that of the return air even though the dry bulb temperature of the outside air may be lower than that of the return air. When the outside air enthalpy is less than the return air enthalpy, the outside air damper, the return air damper, and the cooling valve may be modulated in sequence to provide the proper supply air temperature. This strategy should be used in climates where the humidity is high or is not constant.

The DDC controller uses a temperature sensor mounted in the outside air to close the outside air damper to a minimum position when the outside air temperature exceeds the economizer setpoint. When the outside air temperature is less than the economizer setpoint, the outside air damper, the return air damper, and the cooling valve may be modulated in sequence to provide the proper supply air temperature. This strategy should only be used in climates where the humidity is constant.

This sensor should be mounted in the return air duct. Use a transmitter assembly that provides a 0-10vdc signal output to indicate enthalpy conditions. This sensor must have an insertion probe or duct-mounting capabilities.

Enthalpy Comparison

Dry Bulb

Design Considerations Return Air Enthalpy Sensor

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This sensor should be mounted in the outside air duct. Use a transmitter assembly that provides a 0-10vdc signal output to indicate enthalpy conditions. The transmitter housing must be weatherproof and must have an insertion probe or duct-mounting capabilities.

This sensor should be mounted on the wall with the northernmost exposure. If mounting the sensor on an outside wall is not possible, then mount a probe-type sensor in the outside air duct. Mounting the sensor in the duct has one drawback: in this location, the sensor is subject to reading stagnant air when the outside air damper is closed. Use a weatherproof housing with a sun shield and a windshield to reduce the possibility of false readings. It is recommended that a humidity element be incorporated in the housing for other control functions.

Outside Air Enthalpy Sensor


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13

Optimal Start System Flow Diagram

The DDC controller uses a temperature sensor mounted in the outside air, the space, or a mass sensor in the walls of the building to determine the optimal time to start the air-handling unit.

Avoid using a space mounted temperature sensor. Use a mass sensor for this application. The reason for this sensor choice is because the floors, walls, and ceilings in a building can cause the space to feel cold even if the space temperature setpoint is satisfied. It is very important not to mount the mass sensor in any hollow spaces such as behind a wall where drafts may be present. This sensor must be mounted inside of the wall material. When using this sensor on a new project, be sure to have the sensor mounted in the walls material before the wall is finished. Do not place the mass sensor in an exterior wall or within five feet of an exterior wall.

This sensor should be mounted on the wall with the northernmost exposure. If mounting the sensor on an outside wall is not possible, then mount a probe type sensor in the outside air duct. Mounting the sensor in the duct has one drawback: in this location, the sensor is subject to reading stagnant air when the outside air damper is closed. Use a weatherproof housing with a sun shield and a wind shield to reduce the possibility of false readings. It is recommended that a humidity element be incorporated in the housing for other control functions.

Sequence of Operation

Design Considerations Temperature Sensor


14

Filter Clean/Dirty Pickup Installation

Gage Installation Diagrams

Notice the orientation of the sensing tubes. This is the proper mounting and installation of the sensing tubes for the proper indication of the pressure drop across the filter bank. This method should be used for all situations regardless of the type of sensing device to indicate the pressure drop of the air across a medium

Part Number Description Vendor

Filter Clean/Dirty Status

NO EXCEPTIONS!

0.05-2 W.C. Differential Pressure Switch Kele RH-3-2 Duct Impact Tube Kele #21121

15

Duct Static Pressure Pickup Installation

Duct Static Pressure Notice the orientation of the sensing tube. This is the proper mounting and installation of the sensing tube for the proper indication of duct static pressure. This method should be used for all situations regardless of the type of sensing device to indicate the duct static pressure NO EXCEPTIONS! When used on a VAV system air-handling unit, mount the sensing tube at the farthest VAV box from the unit. This will ensure that all VAV boxes are supplied with the proper amount of air.


PV3 0-5 W.C. Differential Pressure Transmitter Computrols T30-030 0-3 W.C. Differential Pressure Transmitter Kele

Duct Sensing Tube Kele A-301 Duct Flange Kit Kele A-345

Typical Averaging Element Installation

Install the averaging element in a ser n. Use M648 capillary supports for connection to the duct.


pentine fashion as show

ST-FZ3-12 12 Averaging Temperature Element Kele ST-FZ3-25 25 Averaging Temperature Element Kele

M-648 Capillary Mounting Clip Kele

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Pressure Device Mounting Detail

When mounting any type of device to a pipe, the mounting shown above must be used to provide adequate vibration isolation NO EXCEPTIONS!

Part Number Vendor Description

P74FA-5 FNPT Liquid Differential Pressure Switch Kele

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Typical Pipe Strap

-On Element Installation

Part Number Description Vendor Pipe Strap-on Temperature Element Kele ST-R3S

Adjustable Pipe Bracket Kele APB-28 Thermal Conductive Compound Kele TCC-12

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Typical Immersion Type Element Installation

Part Number Description Vendor Immersion Temperature Element

with Well and Handibox Kele ST-W3-XH

Immersion Temperature Element with Well and Weatherproof Box

Kele ST-W3-XW

Thermal Conducting Compound Kele TCC-12

Typical Outside Air Temperature Element Installation

Install sensor on the wall with the northernmost exposure.


Outside Air Temperature Element Kele ST-O3

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Typical Space Temperature Element Installation

Part Number Description Vendor Space Temperature Element Kele ST-S3E

Space Temperature Element with Setpoint Adjustment

Kele ST-S3E-XA

-XJ1 Space Temperature Element with Internal Communications Jack

Kele ST-S3E

Space Temperature Element with Setpoint Adjustment and Internal Communications

Jack

Kele ST-S3E-XA-XJ1

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Typical Space Temperature/Humidity Element Installation

Part Number Description Vendor Space Temperature/Humidity Element Kele HW10K-T3

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Typical Duct High/Low Limit Switch Installation

Part Number Description Vendor A70HA-1 Manual Reset Low Limit Switch Kele A70KA-1 Manual Reset High Limit Switch Kele

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Typical Current Sensor Installation

Part Number Description Vendor Solid Core Go/No Current Sensor Veris H-800 Split Core Go/No Current Sensor Veris H-900

Split Core Go/No Current Sensor with Start/Stop Relay Veris H-930 Split Core Analog Current Sensor Veris H-922

Split Core Analog Current Sensor with Start/Stop Relay Veris H-932

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Typical KW/KWH Transducer


H6001 KW/KWH Transducer in NEMA 1 Enclosure Veris KWH LCD Display Front Mounted in H6001 Veris H6002

KW/KWH LCD Displays Front Mounted in H6001 Veris H6004 KW/KWH Transducer for Mounting in Field Enclosure Veris H6005

100 Ampere CT Small Veris 6810-100 200 Ampere CT Small Veris 6810-200 300 Ampere CT Small Veris 6810-300

400 Ampere CT Medium Veris 6811-400 600 Ampere CT Medium Veris 6811-600 800 Ampere CT Medium Veris 6811-800

800 Ampere CT Large Veris 6812-800 1000 Ampere CT Large Veris 6812-1000 2400 Ampere CT Large Veris 6812-2400

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Typical Belimo Actuator Wiring Schematic

Actuator Sizing Guidelines For control damper actuators, the force needed for 1 square foot of damper = 3.8 in-lb.


LM24 On-Off 35 in-lb 24VAC Actuator Belimo LM24SR Proportional 2-10VDC 35 in-lb 24VAC Actuator Belimo NM24 On-Off 75 in-lb 24VAC Actuator Belimo

Proportional 2-10VDC 75 in-lb 24VAC Actuator Belimo NM24SR On-Off 160 in-lb 24VAC Actuator Belimo AM24

AM24SR Proportional 2-10VDC 160 in-lb 24VAC Actuator Belimo GM24 On-Off 266 in-lb 24VAC Actuator Belimo

GM24SR Proportional 2-10VDC 266 in-lb 24VAC Actuator Belimo

Typical Control Enclosure


RET1820 18 X 20 NEMA 1 Enclosure with Perf Panel Kele 26 X 20 NEMA 1 Enclosure with Perf Panel Kele RET2620 38 X 26 NEMA 1 Enclosure with Perf Panel Kele RET3826 42 X 30 NEMA 1 Enclosure with Perf Panel Kele RET4230

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Tips for Bendin

g Conduit for Stub-ups

Bending Method 1 - Marking the Conduit

From the desired stub-up height, subtract the bender take-up and make a mark on the conduit at a distance from the end equal to the result. Tool take-up for stubs is a characteristic of the bender and is usually marked on the bender as shown above. The following table lists the take-up for common sizes of hand benders:

Hand Bender Size EMT in Inches

Groove Take-up in Inches

5 6 1 7

1 11

The figures listed in the above table are for benders with a shoe designed to make bend to NFPA 70 (N.E.C.) radii. Example: Assume that a bender has a 6 take-up. To make a 9 high stub using either EMT or rigid conduit, subtract 6 from 9 and mark the conduit 3 from the end. Position the arrow on the bender opposite this mark and make a 90-degree bend. If the bender doesnt have an arrow, use the mouth of the bender groove in place of the arrow as the starting point and make the bend. Check the result against the intended rise and mark your own arrow on the bender at the appropriate point.

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The second way for making 90-degree stub-up bends when time is a major factor. This method uses no rulers or marking. Just place your thumbnail on the conduit at the stub height distance and position the conduit in the bender so that an imaginary plumb line from the outside heel of the bender groove is in alignment with your thumbnail as shown above. For the best results, bend the conduit on the floor.

Bending Method 2 - Thumbnail and Eyeball

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Valve Piping Illustrations

Valve Tips The water system should always be flushed before the valves are installed to remove welding debris and other foreign material that may cause the valves to stick.

Never pipe globe valves designated as mixing valves in diverting applications. The valve will hammer as the plug gets closer to the seat. This does not apply to ball valves. All pneumatic valves should be mounted in the upright position. If the valve must be mounted in excess of 45-degrees from the vertical position, the actuator must be supported. A valve with an electric actuator should never be mounted beyond the horizontal position. The electric actuator must be mounted above the valve so that condensation or leaks from faulty packing doesnt short the actuator. Never remove or cover the tag on the valve with insulation material.

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3-Way Butterfly Valve Configurations

Drill and Screw Size Chart This chart lists the high-speed steel drill bits that are used in installations. The tap sizes, wood screw, and self-tapping sheet metal screw sizes for each drill bit are also listed.

Bit Size Decimal

Equivalent

To Tap For This Size Bolt

or Screw Wood Screw

Sheet Metal Screw

#36 .1069 6 X 32 #9 #6 #29 .1360 8 X 32 #12 #8 & #10 #25 .1495 10 X 24 #14 #10 & #12

5/32 .1562 ------ ------ #12 3/16 .1875 ------ #18 #14

#7 .2010 1/4 X 20 ------ ------ 7/32 .2187 1/4 Pipe ------ ------ .2500 ------ ------ ------

5/16 .3125 1/8 Pipe ------ ------ 3/8 .3250 ------ ------ ------ 7/16 .4375 1/4 Pipe ------ ------ 1/2 .5000 ------ ------ ------

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Sensor Networks The following schematic shows various 10K ohm thermistor TYPE III sensor networks. These networks may be used when only one analog input point is used to receive readings from multiple sensors. An example is when an averaging-type element is used to sense the temperature across the face of a coil. The averaging element must be installed in a serpentine fashion across the coil. A problem arises when the coil face is large enough that one averaging element is not long enough to span the entire face of the coil. In this case, a sensor network must be used.

The following equations are used to determine the total required serpentine length of the sensing element.

Vertical Serpentine: Length in Feet = W

TYPICAL SENSOR NETWORKS

x (H2 + 144) 144

Horizontal Serpentine:

Length in Feet = H x (W2 + 144) 144

Note: H = Height in inches W = Width in inches

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Reference Data Conversion Factors

MULTIPLY BY TO OBTAIN MULTIPLY BY TO OBTAIN

Atmospheres 14.70 Lbs./sq. inch (Absolute)

Gallons of Water 8.34 Pounds

Atmospheres 2116.8 Lbs./sq. inch (Absolute)

Horsepower (Boiler) 33.479 B.T.U./hr. Horsepower (Boiler) 9.803 Kilowatt-hrs.

B.T.U/min. 0.02356 Horsepower Inches 2.54 Centimeters B.T.U/min. 0.01757 Kilowatts

Inches of Water 0.03613 Lbs./sq. inch Feet 30.48 Centimeters

Liters 61.02 Cubic inches Liters 0.264 Gallons Feet of Water 0.4335 Lbs./sq. inch (62F)

Gallons 231 Cubic inches Tons of Refrigeration 12000 B.T.U./hr

Heating and Cooling Calculations

CFM = Cubic feet of air per minute passing through the coil Weight per cu ft = Weight of 1 pound (.075) Sp ht = BTU required to raise the temperature of 1 lb of air 1 degree F (.24) To = Temperature of air entering coil in degrees F. T = Temperature of air leaving coil in degrees F. T1 = Temperature of water leaving coil in degrees F. T2 = Temperature of water entering coil in degrees F. H1 = Enthalpy of entering air. H2 = Enthalpy of leaving air.

Capacity of Hot Water Coil

DC Cur

rent Kilowatts KW = {Amps X Volts}/1000

GPM = CFM X 1.08 X (T To) (T2 T1) X 500

Capacity of Chilled Water Coil H ) X CFM X .075 X 60GPM = (H

AC Single Phase Kilowatts KW ={Amps X Volts X Power Factor}/1000 AC Three Phase Kilowatts KW = {Amps X Volts X 1.73 X Power Factor}/10

1 2 (T2 T1) X 500

Chiller Coefficient of Performance Chiller Tonnage TONS = GPM X (CHWR CHWS)

24 COP = (CHWR CHWS) X GPM X 0.0417

0.28433 X KW

VAV Box Air Flow Rate (CFM)

CFM = Cubic feet of air per minute passing through the duct A = Duct area in sq. ft. V = Velocity of the air Pv = Pressure in inches of H2O from PV3

Equation Q = AV 0.0763 is the density of dry air at 60o F The duct diameter units are in ft. CFM = 1096(Duct Diameter/2)2((Pv/.0763))

Linear Reset Schedule Formula The linear reset schedule is used to reset a particular setpoint based on a particular parameter. Some examples are:

Boiler hot water supply temperature reset based on the outside air temperature. In this instance, the hot water bypass valve is modulated to control the temperature of the water flow. Supply air temperature reset based on the space zone calling for the most cooling or heating. Chilled water supply temperature reset based on the chilled water return temperature.

Y = The variable that is reset m = The slope of the reset line x = The parameter that the reset is based upon b = System constant that defines the equation of the line Y1 = Minimum value of the reset variable Y2 = Maximum value of the reset variable X1 = Minimum value of the dependent value X2 = Maximum value of the dependent value

1, Y2, X1, and X2.

air temperature is 50 degrees F or below, the

hot water supply temperature should be reset to 140 degrees F. When the outside air temperature is 90 degrees F or above, the hot water supply temperature should be reset to 110 degrees F. From the sequence of operation above, Y1 = 140, Y2 = 110, X1 = 50, and X

STEP 2

STEP 1: Determine the minimum and maximum values of the system, i.e. Y

Example: Boiler hot water reset schedule. When the outside

2 = 90.

: Determine the slope of the line. m = Y2 Y1 = 110 140 = -30 = -0.75 X2 X1 90 50 40 STEP 3

STEP 4

: Determine b. Plug in the known parameters into the equation of the line and solve for b.

Y = mx + b b = Y mx = 140 (-0.75)(50) = 72.5 b = 177.5

: Plug in the calculated values for m and b into the equation for a line.

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Y = mx + b = (-0.75)x + 177.5 Here, Y is the HOT WATER SUPPLY TEMPERATURE and x is the OUTSIDE AIR TEMPERATURE. Although CBAS 2000 calculates linear reset equations automatically with the RESET SCHEDULE function, a sample calculation point in another program for this example would look like:

HOT WATER SUPPLY TEMPERATURE = -0.75 X OUTSIDE AIR TEMPERATURE + 177.5

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Control Valve Sizing General Guidelines Most control valves used for HVAC control fall into one of four categories:

1. Two position valves (water or steam) 2. Proportional control of water varying the amount of flow (chilled and hot water coils, differential

pressure control) 3. Proportional control of water varying the temperature of the flow (boiler hot water bypass and

condenser water bypass) 4. Proportional control of steam

Usually, the pipe size will be larger than the valve size. In this case, the pipe must be fitted down to the valve. This reduction affects the flow characteristics of the valve and reduces the effective Cv of the valve. This effect is known as the PIPING GEOMETRY FACTOR (symbol = Fp). Use the charts on the reverse side of this page to determine the actual Cv of a valve when it is installed in a larger pipe.

A low

STEP 1 Determining The Correct Pressure Drop (P)

1. TWO POSITION VALVES: WATER OR STEAM -pressure drop across the valve is desirable.

P = 10% of the available pressure If pressure is not known, it is best to go with a

line size valve.

In this system, 20 PSI is the available pressure. Valve should be sized to have a 2 PSI drop.

2. PROPORTIONAL CONTROL OF WATER: VARYING THE AMOUNT OF FLOW A high-pressure drop across the valve is desirable.

hot water coils.

pressure control applications.

In this system, 4.3 PSI should be used as the pressure drop.

Use a P = 4.3 for control valves for chilled and

A P = 4.3 may also be used for differential

3. PROPORTIONAL CONTROL OF WATER: VARYING THE TEMPERATURE OF THE FLOW A low-pressure drop across the valve is desirable.

of the available pressure P = 10% P = 25% of the P thru load @ full flow

In this system, the amount of water to the coil doesnt change. The valve controls the percentage of the flow coming from the boiler. By modulating the valve, the supply temperature is varied.

4. PROPORTIONAL CONTROL OF STEAM

Under 15 PSIA very high-pressure drop across the valve is desirable.

For 15 PSI steam or less: - P = 80% of inlet gauge pressure - Choose valve which is at least 1 size smaller than line size

For greater than 15 PSI steam: - P = 42% of absolute pressure (Gauge pressure + 14.7 then multiply by 0.42) Do not be alarmed by the seemingly high Ps that are recommended for steam. Due to the nature of steam and its heating abilities, it requires a high-pressure drop for proper control.

Inlet pressure: 10 PSI X (80%): .8 8 PSI 8 PSI is the desired pressure drop Over 15 PSI Inlet pressure: 35 PSI Adjust to PSIA (Absolute): +14.7 49.7 PSI X 0.42 20.87 PSI 20.87 PSI is the desired pressure drop

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STEP 2 Calculating Cv 1. WATER SYSTEMS:

Cv = GPM P

2. STEAM SYSTEMS: Cv = LBS per HOUR

3 X (P X PO) Where PO = Inlet pressure (PI) - P

On the reverse side of this page, find the corrected Cv by referencing the pipe size and the valve size on the PIPING GEOMETRY CORRECTION FACTOR CHART. Verify that the corrected Cv is not less than the calculated Cv. If the corrected Cv is less than the calculated Cv, choose the next larger size valve. The selected valve should never be smaller than the pipe size.

STEP 3 Valve Selection Select the type of valve needed, i.e. ball, globe, or butterfly which most closely matches the required Cv calculated in Step 2. Choose a valve that has a slightly larger Cv than the calculated Cv. STEP 4 Correct For Piping Geometry Factor (Fp)

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39

Adjusted CV Ratings For Piping Geometry Factor (Fp)

2-Way Ball Valves Valve Valve Pipe Size

Size Model # 1/2" 3/4" 1" 1-1/4" 1-1/2" 2" 2-1/2" 3" 4" 5" 6"

0.50 05-2-004 0.4 .39 .39 .39 --- --- --- --- --- --- ---

0.50 05-2-01 1.00 .99 .99 .99 --- --- --- --- --- --- ---

0.50 05-2-02 2.00 1.96 1.94 1.92 --- --- --- --- --- --- ---

0.50 05-2-04 4.00 3.75 3.58 3.50 --- --- --- --- --- --- ---

0.50 05-2-10 9.80 7.38 6.30 5.86 --- --- --- --- --- --- ---

0.75 75-2-25 --- 25.00 19.53 16.26 14.75 --- --- --- --- --- ---

1.00 1-2-35 --- --- 35.00 31.08 27.35 23.80 --- --- --- --- ---

1.25 125-2-47 --- --- --- 47.00 43.97 37.55 34.48 --- --- --- ---

1.50 150-2-81 --- --- --- --- 81.00 68.01 58.84 54.25 --- --- ---

2.00 2-2-105 --- --- --- --- --- 105.00 97.89 90.30 81.66 --- ---

3.00 3-2-390 --- --- --- --- --- --- --- 390.00 307.76 257.40 233.89

0.75 75-2-33 --- 33.00 22.71 17.96 15.98 --- --- --- --- --- ---

1.00 1-2-47 --- --- 47.00 38.60 32.06 26.71 --- --- --- --- ---

1.25 125-2-81 --- --- --- 81.00 67.90 49.46 43.00 --- --- --- ---

1.50 150-2-105 --- --- --- --- 105.00 80.47 66.15 59.97 --- --- ---

2.00 2-2-210 --- --- --- --- --- 210.00 165.90 134.61 110.48 --- ---

2.50 250-2-440 --- --- --- --- --- --- 440.00 329.00 217.00 184.31 ---

Example: What is the correct Cv rating of a 75-2-25 valve when placed in a 1" pipe? Look at 1" column and cross over to the valve model #. As one can see, the correct Cv rating is 19.53. These values also apply to stainless steel ball and stem (SSBS) and stainless steel bodied valves (SS) where applicable.

2-Way Flanged Ball Valve

Valve Valve Pipe Size

Size Model # 3" 4" 5" 6" 8" 10" 12"

3.00 3-2-600 600.00 384.6 297.47 262.77 --- --- ---

4.00 4-2-1200 --- 1200.00 803.00 605.63 476.85 --- ---

6.00 6-2-3300 --- --- --- 3300.00 1713.11 1265.42 1102.07

3-Way Ball Valves


Size Model # 1/2" 3/4" 1" 1-1/4" 1-1/2" 2" 2-1/2" 3" 4" 5" 6"

0.50 05-3-02 2.00 1.96 1.94 1.92 --- --- --- --- --- --- ---

0.50 05-3-06 6.00 5.25 4.82 4.62 --- --- --- --- --- --- ---

0.75 75-3-12 --- 12.00 11.20 10.46 10.02 --- --- --- --- --- ---

1.00 1-3-14 --- --- 14.00 13.70 13.33 12.85 --- --- --- --- ---

1.25 125-3-21 --- --- --- 21.00 20.70 19.90 19.40 --- --- --- ---

1.50 150-3-30 --- --- --- --- 30.00 29.17 28.31 27.75 --- --- ---

2.00 2-3-50 --- --- --- --- --- 50.00 49.16 48.08 46.66 --- ---

2.00 2-3-91 --- --- --- --- --- 91.00 86.25 80.77 74.53 --- ---

3-Way Flanged Ball Valve Valve Valve Pipe Size

Size Model # 3" 4" 5" 6" 8" 10" 12"

3.00 3-3-135 135.00 130.00 125.59 122.56 --- --- ---

4.00 4-3-230 --- 230.00 224.97 218.55 210.31 --- ---

6.00 6-3-330 --- --- --- 330.00 325.61 320.82 317.59

Adjusted CV Ratings For Piping Geometry Factor (Fp) 2-Way Globe Valves


Size Model # 1/2" 3/4" 1" 1-1/4" 1-1/2" 2" 2-1/2" 3" 4" 5" 6"

0.50 DG05-2-03 2.5 2.43 2.38 2.36 --- --- --- --- --- --- ---

0.75 DG75-2-07 --- 6.3 6.17 6.04 5.95 --- --- --- --- --- ---

1.00 DG1-2-10 --- --- 10 9.89 9.74 9.55 --- --- --- --- ---

1.25 DG125-2-16 --- --- --- 16 15.86 15.49 15.25 --- --- --- ---

1.50 DG150-2-25 --- --- --- --- 25 24.51 23.99 23.65 --- --- ---

2.00 DG2-2-40 --- --- --- --- --- 40 39.57 38.99 38.22 --- ---

2.50 DG250-2-63 --- --- --- --- --- --- 63 62.50 61.08 59.6 ---

3.00 DG3-2-100 --- --- --- --- --- --- --- 100 98.06 94.62 ---

4.00 DG4-2-160 --- --- --- --- --- --- --- --- 160 155.99 ---

5.00 DG5-2-250 --- --- --- --- --- --- --- --- --- 248.06 242.52

6.00 DG6-2-400 --- --- --- --- --- --- --- --- --- 400 371.35

3-Way Mixing Valves


Size Model # 1/2" 3/4" 1" 1-1/4" 1-1/2" 2" 2-1/2" 3" 4" 5" 6" 8" 10"

0.50 DG05-3-03 2.5 2.43 2.38 2.36 --- --- --- --- --- --- --- --- ---

0.75 DG75-3-07 --- 6.3 6.17 6.04 5.95 --- --- --- --- --- --- --- ---

1.00 DG1-3-10 --- --- 10 9.89 9.74 9.55 --- --- --- --- --- --- ---

1.25 DG125-3-16 --- --- --- 16 15.86 15.49 15.25 --- --- --- --- --- ---

1.50 DG150-3-25 --- --- --- --- 25 24.51 23.99 23.65 --- --- --- --- ---

2.00 DG2-3-40 --- --- --- --- --- 40 39.57 38.99 38.22 --- --- --- ---

2.50 DG250-3-63 --- --- --- --- --- --- 63 62.50 61.08 60.16 59.6 --- ---

3.00 DG3-3-100 --- --- --- --- --- --- --- 100 98.06 95.99 94.62 --- ---

4.00 DG4-3-160 --- --- --- --- --- --- --- --- 160 158.28 155.99 154.21 ---

5.00 DG5-3-250 --- --- --- --- --- --- --- --- --- 250 248.06 245.09 242.54

6.00 DG6-3-400 --- --- --- --- --- --- --- --- --- --- 400 380.77 371.37

3-Way Mixing Valves


Size Model # 1/2" 3/4" 1" 1-1/4" 1-1/2" 2" 2-1/2" 3" 4" 5" 6" 8"

0.50 DDG05-3-04 4 3.75 3.58 3.5 --- --- --- --- --- --- --- ---

0.75 DDG75-3-08 --- 8 7.75 7.49 7.32 --- --- --- --- --- --- ---

1.00 DDG1-3-15 --- --- 15 14.6 14.19 13.6 --- --- --- --- --- ---

1.25 DDG125-3-20 --- --- --- 20 19.74 19.04 18.06 --- --- --- --- ---

1.50 DDG150-3-28 --- --- --- --- 28 27.32 26.61 26.15 --- --- --- ---

2.00 DDG2-3-40 --- --- --- --- --- 40 39.57 38.99 32.22 --- --- ---

2.50 DDG250-3-68 --- --- --- --- --- --- 68 67.37 65.61 64.47 --- ---

3.00 DDG3-3-85 --- --- --- --- --- --- --- 85 83.80 82.49 81.62 ---

4.00 DDG4-3-160 --- --- --- --- --- --- --- --- 160 158.28 155.99 152.91

5.00 DDG5-3-195 --- --- --- --- --- --- --- --- --- 195 194 191.4

6.00 DDG6-3-250 --- --- --- --- --- --- --- --- --- --- 250 248.07

Example: What is the correct Cv rating of a 75-3-07 valve when placed in a 1" pipe? Look at 1" column and cross over to the valve model #. As one can see, the correct Cv rating is 6.17. These values also apply to stainless steel trim valves (SS).

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Table of ContentsControl of Supply Air Temperature System Flow DiagramDesign Considerations

Control of HumiditySequence of OperationDesign ConsiderationsHumidity SensorSoftware Configuration

Space or Room Air ControlSequence of OperationDesign ConsiderationsLow Limit Switch or FreezestatSoftware Configuration

Control of Duct Static PressureSupply Fan Variable Frequency Drive Control

Outside Air Temperature LockoutSequence of Operation

Temperature Setpoint ResetOutside Air EconomizerSequence of Operation

Optimal StartSequence of Operation

Filter Clean/Dirty Pickup InstallationDuct Static Pressure Pickup InstallationTypical Averaging Element InstallationPressure Device Mounting DetailTypical Pipe Strap-On Element InstallationTypical Immersion Type Element InstallationTypical Outside Air Temperature Element InstallationTypical Space Temperature Element InstallationTypical Space Temperature/Humidity Element InstallationTypical Duct High/Low Limit Switch InstallationTypical Current Sensor InstallationTypical KW/KWH TransducerTypical Belimo Actuator Wiring SchematicTypical Control EnclosureTips for Bending Conduit for Stub-upsBending Method 2 - Thumbnail and Eyeball

Valve Piping IllustrationsDrill and Screw Size ChartSensor NetworksReference DataControl Valve SizingUnder 15 PSIOver 15 PSISTEP 2 Calculating CvSTEP 3 Valve SelectionSTEP 4 Correct For Piping Geometry Factor (Fp)

ddc technical manual

Documents

typical control enclosure

typical pipe strap

typical kwkwh transducer

air temperature lockout

room air control

air economizer

control of humidity

temperature setpoint