DPT-2015 Differential Pressure Transmitter for VAV Box Applications

FANs 216, 1628.3

Product/Technical Bulletin DPT-2015 Issue Date 1298

© 1998 Johnson Controls, Inc. 1

DPT-2015 Differential Pressure Transmitter for

VAV Box Applications

The DPT-2015 Differential Pressure Transmitter senses differential pressure in pressure-independent Variable Air Volume (VAV) applications. It sends an analog signal that is proportional to velocity pressure to a VAV controller. The DPT-2015 is typically

mounted to the EDA-2040 Electric Damper Actuator or to the Johnson Controls VAV controller for reliable damper positioning in closed-loop applications. It also can be mounted alone as an independent pressure transmitter or used for damper positioning in other VAV systems.

Figure 1: DPT-2015 Differential Pressure Transmitter

Features and Benefits

‰‰ Integral Pressure Transmitter

with Dead Ended Input Ports

No inline filter or maintenance required; prevents sensor contamination

‰‰ One Model: 0 to 1.5 in. Water Column (W.C.) Input Pressure Range

Satisfies the requirements for virtually all terminal box applications

‰‰ 0.5 to 4.5 VDC Output Compatible with a wide variety of HVAC

controllers

‰‰ No Warmup Period Allows for immediate commissioning after

power up

‰‰ Capacitive Sensor

Technology

Provides long-term stability and accuracy

‰‰ 4 VDC Output Span Replaces DPT-2000-2 when used as

P

roduct Overview

The DPT-2015 is connected to the VAV box airflow pickups. It measures differential pressure and generates a proportional voltage signal. The voltage signal from the DPT-2015 is read by the VAV controller and converted to airflow in cubic feet per minute (cfm). Calibration is not required other than zero calibration, which is performed within the controller.

A

pplication

The DPT-2015 is used to measure differential pressure to determine the air velocity for calculating airflow.

The DPT-2015 is available factory mounted to an EDA-2040 Series actuator as an ATP-2040 or factory mounted to a Johnson Controls VAV Series controller as an AS-VAVDPT. It is most commonly field mounted to an EDA-2040 Series actuator as shown in Figure 2. It can also be mounted separately as shown in Figure 3.

E D A-2 0 4 0 To C ontr oller T o A irf low P ickup IN GN D OU T Black R ed B lue U P DP T -201 5-0 (- ) LO

Figure 2: DPT-2015 Mounted on an EDA-2040

Figure 3: Typical Standalone Installation

The DPT-2015 can be used with the Johnson Controls VAV Series controller (as shown in Figure 4) or any other controller capable of the following:

• controller provided or external power supply of 15 VDC for input power to the DPT-2015

• 25,000-ohm minimum input impedance to accept input of 0.5 to 4.5 VDC from the output of the DPT-2015

Note: For best results, select a controller with auto zero capability.

1 V A V C ontroller H T G 1 D P T -2015 E D A -2040 T E V A

Figure 4: DPT-2015 Typical Applications

I

nstallation

The DPT-2015 can be installed on the EDA-2040 Electric Damper Actuator or any other flat surface using the two self-tapping screws provided. The

A irflo w (-) LO D PT-20 15-0 UP INNG D O U T

Parts Included

• DPT-2015-0 Differential Pressure Transmitter • No. 6 x 1/4 in. thread-forming Plastite screws (2)

Tools Required

• No. 2 Phillips screwdriver • 1/4 in. female quick connects (3)

or

• CBL-2000-x Wiring Harness with quick connects for easy wiring to the Johnson Controls VAV Series controller and the EDA-2040 Electric Damper Actuator.

Note: The 20 in. (0.5 m) CBL-2000-1, accepted by Underwriters Laboratories (UL) for plenum use, is included with the ATP-2040. The 20 in. (0.5 m) CBL-2000-2 and 72 in. (1.8 m) CBL-2000-3, both plenum rated, have to be ordered separately. (See Table 2.)

D

imensions

Figure 5: DPT-2015 Dimensions, in. (mm)

M

ounting on an EDA-2040

Check the EDA-2040 cover for two inside mounting bosses. If there are none, order the DPT-2015-MNT to mount the DPT-2015 to your EDA-2040.

Note: The DPT-2015-0 is also available

preassembled to the DPT-2015-MNT and can be ordered as the DPT-2015-1.

If mounting bosses are present as shown in Figure 6, proceed as follows:

1. Unpack the DPT-2015 and the two No. 6 x 1/4 in. thread-forming Plastite screws included. 2. Align the two mounting holes located on the

DPT-2015 with the inside mounting bosses located on the top of the EDA-2040. (See Figure 6.)

Figure 6: EDA-2040 with Two Inside Mounting Bosses

3. Attach the DPT-2015 to the top of the EDA-2040 with the screws as shown in Figure 2, using a No. 2 Phillips screwdriver.

IMPORTANT: Secure the nonslotted hole on the DPT-2015 first, followed by the slotted mounting hole to avoid stressing the transmitter’s housing. Avoid overtightening the screws to prevent stripping the holes. Note: Refer to the EDA-2040/ATP-2040 Electric

Damper Actuator Technical Bulletin (FAN 121, 1628.3, or 268.1) to complete actuator installation. U P 0 .15 D iam e ter 3 .8 0 .60 1 5.0 1 .25 3 1.7 2 .2 0 5 5.9 1 .95 4 8.3 1 .25 3 1.7 IN O U T G N D In su la te d M a le S p ad e Te rm in als (3) 0 .25 6 .35 1 .29 3 2.8 1 /4 in . B a rb ed P o rts (2 ) 0 .2 5 6 .3 5 1 /4 in . Tu bing 6.0 1 52 .4 W ire Le ad s (3 ) 8 .0 2 03 .0 0 .15 3 .8 1.0 2 2 5.9 In side M o un tin g B o sse s

U

sing the Mounting Kit

The DPT-2015-MNT Mounting Kit is available to replace a DPT-2000 or retrofit to the EDA-2040 without mounting bosses (date code prior to 9540). To order the DPT-2015 preassembled to the mounting bracket, specify DPT-2015-1.

To install the DPT-2015-MNT Mounting Kit: Note: Skip Steps 1 and 2 if the DPT-2015-1 is

already available.

1. Align the mounting holes on the DPT-2015 with the two inside mounting holes on the mounting bracket provided in the kit.

2. Attach the DPT-2015 to the mounting bracket with the two No. 6 x 1/4 in. sheet metal screws as shown in Figure 7, using a No. 2 Phillips screwdriver. IMPORTANT: Secure the nonslotted mounting hole

on the DPT-2015 first, followed by the slotted mounting hole to avoid stressing the transmitter’s housing.

Figure 7: Installation of DPT-2015 Using the DPT-2015-MNT Mounting Kit

A

ir Pressure Connections

The flow pickup device provided with the VAV box must be connected to the DPT-2015 using field-supplied 1/4 in. O.D. tubing as follows:

1. Cut two lengths of tubing, and connect them to the flow pickup device.

IMPORTANT: Make sure the tubing is properly sized and made of an elastic material, such as silicone rubber, to ensure airtight connections and minimize flow measurement errors.

2. Connect the tubing from the flow pickup device to the corresponding barbed high- and low-pressure ports on the DPT-2015.

Note: The low-pressure port is indicated as (-)LO on the transmitter. (See Figure 8.)

Figure 8: DPT-2015 Side View

!

Overpressure limit is 15 in. W.C. Do not blow into ports to test the operation as this may damage the sensing element.

IMPORTANT: Make sure that the pressure ports are pointing down by routing the tubing so a portion of it is lower than the DPT-2015. This creates a trap that prevents any condensation from entering the sensor. Do not make any sharp bends in the tubing. This M ou ntin g

B ra cke t N o . 6 x 1/4 in . S h ee t M e ta l S cre w s (2 )

N o . 8 x 3/8 in . Th re ad -fo rm ing S cre w s (2)

E D A -20 40 IN GND OU T (-)LO D P T -20 15 -0 U P B lue R e d B lack E D A -20 40 M ou n ted to a VAV B o x D P T -20 15 1 /4 in . B a rb ed P o rts fo r F ie ld-su pp lied Tu bing

C B L -2 00 0-x C a ble H arn ess fo r C o nn ection to a

VAV C o ntroller N o te: U p pe r p ort is the lo w -p ressure con ne ctio n, (-)L O .

W

iring

The DPT-2015 requires a 15 VDC power signal (14.5 to 17 VDC, unregulated) and provides a nominal 0.5 to 4.5 VDC control signal. It is compatible with a variety of controllers, including the Johnson Controls VAV Series controller. All wiring must be in

accordance with the National Electrical Code and applicable local code requirements.

!

Disconnect all power supplies to the system before wiring the DPT-2015 to avoid damage to equipment or possible electrical shock.

1. Wire the power common and signal common from the controller to the black GND (Common) wire on the DPT-2015.

2. Locate the power output terminal on the controller (or separate power supply), and wire it to the red IN wire on the DPT-2015. The supply power must be between 14.5 and 17 VDC, unregulated. 3. Locate the analog input terminal on the controller,

and wire it to the blue OUT wire on the DPT-2015.

IMPORTANT: Upon completion of wiring connections, make sure that the wires from the DPT-2015 are routed away from the shaft coupler on the EDA-2040.

Table 1: Wiring Connections

Designation Signal

IN (Red) + Power

(14.5 to 17 VDC)

GND (Black) - Common

OUT (Blue) + Control (0.5 to 4.5 VDC)

B lu e (O UT ) C ontrol R ed (IN ) 15 VD C Power Sup ply Blac k (G ND ) Comm on

(+) (-) (+ )

DPT -201 5-0

Figure 9: DPT-2015 Wiring Diagram

Note: The CBL-2000-x Wiring Harness may be ordered for wiring to the Johnson Controls VAV Series controller and the EDA-2040 Electric Damper Actuator. (See Table 2.)

C

onfiguration and Checkout

1. Perform the checkout procedure provided in the controller instructions to ensure proper operation of the transmitter.

2. When used with a Johnson Controls VAV Series controller, the DPT-2015 must be set up and zeroed using HVAC PRO for Windows. Refer to the Variable Air Volume Controller Technical Bulletin (FAN 636.3 or 1628.2) for details. IMPORTANT: Final commissioning should be

performed when the transmitter is at normal operating temperatures and mounted in its normal operating position.

T

roubleshooting

The DPT-2015 must be auto zeroed by the Johnson Controls VAV controller. If not operating properly:

1. Make sure the air lines on the DPT-2015 are connected to their respective high and low ports and pointing down with no kinks in the tubing. 2. Check voltage to ensure it is within the

14.5 to 17 VDC range and the polarity is correct. 3. Disconnect the air lines from the high and low

ports, and place a voltmeter across Terminals OUT and GND. If the output is not between 0.4 and 0.6 volts with power applied to the

DPT-2015 in the vertical position, the transmitter is defective and should be replaced.

Note: Voltage readings may vary by 0.1 volt if the transmitter is in the horizontal position.

A

irflow Measurement Accuracy

The DPT-2015 provides maintenance-free performance within the control range of 400 to 3000 feet per minute (fpm) when used as recommended with the Johnson Controls VAV controller.

The minimum 400 fpm velocity and the gain of the airflow pickup produces an accurately measured pressure difference.

IMPORTANT: Where accuracy is important, VAV terminal inlets must be sized to maintain air velocity above 400 fpm to determine airflow volume by measuring differential pressure. A velocity pressure of about 0.01 in. W.C. (2.49 Pa) is accepted as the lower limit measurement in

VAV terminals. Pressure-independent VAV terminals utilize an airflow pickup, which amplifies the airstream velocity pressure about 2.25 times, varying by

manufacturer.

Figure 10 illustrates the typical accuracy of the measurement system consisting of the DPT-2015 and VAV controller for the conditions specified.

Indicated fpm Actual fpm 0 0 500 1000 1500 2000 2500 3000 3500 500 1000 1500 2000 2500 3000 3500 + 3F°/+ 1.6C° +10F°/+ 5.5C° Flow Pickup Gain = 2.25

At low flow, transmitter span and non-linearity errors have negligible impact on flow measurement accuracy, but the error envelope widens due to the temperature effect on transmitter offset. (See Figure 11.)

Indicated fpm Actual fpm 0 0 200 400 600 800 1000 1200 200 400 600 800 1000 1200 + 3F°/+1.6C° +10F°/+5.5C°

Flow Pickup Gain = 2.25

Figure 11: Temperature Effect on DPT-2015

The controller auto zero function helps reduce the temperature effect error by zeroing offset errors. When auto zero occurs daily, the remaining temperature effect error is the result of the 24-hour transmitter ambient temperature swing relative to the temperature at which the auto zero occurred.

The error envelope becomes smaller with increased airflow pickup gain and with smaller ambient

temperature deviations at the transmitter location. Both charts show the error envelope for deviations of ±3F° (±1.6C°) and ±10F° (±5.5C°) from the

temperature when auto zero occurred.

O

rdering

Information

Table 2: Ordering Information

Product Code Number Description

DPT-2015-0 0 to 1.5 in. W.C. (0 to 374 Pa) differential pressure transmitter DPT-2015-1 DPT-2015-0 with the DPT-2015-MNT Mounting Kit

DPT-2015-MNT Mounting kit for DPT-2015 (to replace the DPT-2000)

CBL-2000-1 20 in. (0.5 m) wiring harness accepted by UL for plenum use (included with the ATP-2040; connects a DPT-2015 and an EDA-2040 to a VAV controller)

CBL-2000-2 20 in. (0.5 m) plenum rated wiring harness (connects a DPT-2015 and an EDA-2040 to a VAV controller)

CBL-2000-3 72 in. (1.8 m) plenum rated wiring harness (connects a DPT-2015 and an EDA-2040 to a VAV controller)

Note: See the EDA-2040/ATP-2040 Electric Motor Actuator Product Bulletin in the Damper and Actuator Product Guide (FAN 268.1) or the Facilitator Accessories Technical Manual (FAN 1628.3) and the Variable Air Volume Controller Technical Bulletin (FAN 636.3 or 1628.2) for ordering information on the DPT-2015 factory assembled to the above products.

S

pecifications

Product DPT-2015 Differential Pressure Transmitter for VAV Box Applications Power Requirements 15 VDC (14.5 to 17 VDC, unregulated); 15 mA, maximum

Pressure Range 0 to 1.5 in. W.C. (0 to 374 Pa), maximum Overpressure Limit 15 in. W.C. (3.74 kPa)

Output Voltage 0.5 to 4.5 VDC into load impedance of 25,000 ohms minimum AccuracyLinearity _{Linearity: ±1.0% full span, maximum}

Repeatability/Hysteresis: ±0.05% full span, maximum Position Effects Zero Shift: ±0.1 VDC, maximum

Span Shift: ±0.05 VDC, maximum Stability (One year)

Zero Shift: ±0.5% full span Span Shift: ±2% full span

Temperature Effects Zero: ±0.06% of full span per F°, maximum, over 60 to 100°F (15.6 to 37.8°C) range Span: ±1.5% of full span, maximum, over 60 to 100°F (15.6 to 37.8°C) range Power Supply Effects For power supply changes of 14.5 to 17.1 VDC, referenced to 15 VDC

Zero Shift: ±0.01 VDC, maximum Span Shift: ±0.04 VDC, maximum

Terminals 1/4 in. male spade terminals with 8 in. (203 mm) wire length

Pressure Connections 6 in. (152 mm) length of silicone tubing with barbed fittings for 1/4 in. (6.35 mm) O.D. tubing Ambient Operating Conditions 32 to 122°F (0 to 50°C) 90% RH, maximum, non-condensing Ambient Storage Conditions -20 to 150°F (-28.9 to 65.6°C) 90% RH, maximum, non-condensing Dimensions (H x W x D) 1.02 x 2.94 x 2.5 in. (26 x 75 x 63.5 mm)

Shipping Weight 2.5 oz. (0.07 kg)

Agency Compliance UL 916 Listed, File E107041, Guide PAZX

CSA C22.2, No. 205 Certified, File LR68965, Class 4812 05

The performance specifications are nominal and conform to acceptable industry standards. For application at conditions beyond these specifications, consult the local Johnson Controls office. Johnson Controls, Inc. shall not be liable for damages resulting from misapplication or misuse of its products.