Dwyer WHT Manual

Bulletin H-WHT

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Series WHT Weather-Proof Humidity/Temperature Transmitter

Specications - Installation and Operating Instructions

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The Compact Series WHT Weather-Proof Humidity/Temperature Transmitter is

designed to withstand the elements. A removable sintered lter protects the polymer
capacitance sensor from solid objects that may come in contact with the transmitter.

The transmitter is available with 4-20 mA, or 0-10 VDC or 0-5 V output signals for both

temperature and humidity or a passive thermistor for temperature. This transmitter
is ideal for measuring outside air temperature and humidity levels for air handling

economizer applications.

INSTALLATION
Warning: Disconnect power supply before installation to prevent electrical shock and

equipment damage.

CAUTION

codes. Use copper conductors only.

Use electrostatic discharge precautions (e.g., use of wrist straps) during installation
and wiring to prevent equipment damage.

Avoid locations where severe shock or vibration, excessive moisture or corrosive
fumes are present. NEMA Type 3S (IP54) housings are intended for outdoor use
primarily to provide a degree of protection against wind-blown dust, and rain.

Do not exceed ratings of this device, permanent damage not covered by warranty may

result. The 4 to 20 mA models are not designed for AC voltage operation.

Make sure all connections are in accordance with the job wiring

diagram and in accordance with national and local electrical

SPECIFICATIONS
Relative Humidity Range: 0 to 100% RH.
Temperature Range: -40 to 140°F (-40 to 60°C).
Sensor Accuracy, RH: ±2% @ 20 to 80% RH, ±3% @ 10 to 20%, 80 to 90% RH.
Accuracy, Temp Models with 4-20 mA Temp. Output: ±0.9°F @ 72°F (±0.3°C @

25°C).

Accuracy, Temp Models with Passive Thermistor Temp Sensor: ±0.36°F @
77°F (±0.2°C @ 25°C).

Hysteresis, RH: ±1%.
Repeatability, RH: ±0.1% typical.
Temperature Limits: -40 to 140°F (-40 to 60°C).
Storage Temperature: -40 to 176°F (-40 to 80°C).
Compensated Temperature Range, RH: -4 to 140°F (-20 to 60°C).
Power Requirements: 4-20 mA loop powered models: 10-35 VDC; 0-10 V output

models: 15-35 VDC or 15-29 VAC; 0-5 V output models: 10-35 VDC or 10-29 VAC.
Output Signal: 4-20 mA loop powered models: 4-20 mA; 0-10 V output models:
0-10 V @ 5 mA max; 0-5 V output models: 0-5 V @ 5 mA max.

Response Time: 15 s.
Electrical Connections: Removable screw terminal block.
Drift: <1% RH/year.
RH Sensor: Capacitance polymer.
Temperature Sensor: 4-20 mA output, solid state band gap. Passive output: 10K

@ 25°C thermistor (Dwyer curve A).

Enclosure: ABS.
Enclosure Rating: Designed to meet NEMA 3S (IP54).
Weight: 0.3 oz (8.5 g).
Compliance: CE.

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.

Phone: [phone]

Fax: [phone]

www.dwyer-inst.com

e-mail: [e-mail]

MOUNTING

RH RECEIVER

1 2 3 4

1 2 3 4

RH RECEIVER

+–
+–

1 2 3 4 5

1 2 3 4 5

+–

The transmitter should be mounted with the sensor pointing downward to prevent
water collection in the housing. The integral mounting tab has two sets of mounting
holes. The larger holes are for the suspension mounting and the smaller holes are

for surface mounting the transmitter to a wall. Please see Figure 1 and 2 for more

information on both mounting methods.

Figure 1: Suspension mounting Figure 2: Surface mounting

Models with 0-5 V or 0-10 V RH Output, with or without 0-5 V or 0-10 V Temperature
Output

The 0 to 10 V output models may be powered with 15-35 VDC or 15-29 VAC. The 0-5 V
models may be powered with 10-35 VDC or 10-29 VAC. Note the polarity when using

DC power. The channels are common on the negative side. For RH and Temperature

outputs, either or both may be used. The maximum load is 5 mA (1K for 0 to 5 V, 2K
for 0 to 10 V). Wire as shown in Figure 5.

TEMP. RECEIVER

RH RECEIVER

+

POWER
SUPPLY

WIRING

Models with 0-5 or 0 to 10 V RH Output and a Passive Thermistor Temperature

Sensor

The 0 to 5 V or 0 to 10 V RH output is identical to the above model with a 0-5 V or 010

V temperature output. The required power supply and wiring of the RH output is the
same. The passive thermistor temperature sensor wires to terminals 4 and 5. Wire as

shown in Figure 6.

–

Figure 5

TEMP. SENSOR

RH RECEIVER

Figure 6

+
–

POWER
SUPPLY

WIRING

Use maximum 18 AWG wire for wiring terminal. Refer to Figures 3-6 for wiring

information.

Models with 4-20 mA RH Output, with or without 4-20 mA Temperature Output

4-20 mA output units may be powered with a 10-35 VDC supply. The following

describes the proper wiring of these transmitters with mA output.
Models with 4-20 mA RH and 4-20 mA Temperature outputs are designed as a 4-20
mA device with two channels. The channels are common on the positive side of the
current loop.

Sensor excitation is derived from the relative humidity channel, so power must always
be applied to that channel. If the temperature channel is not equipped or used, it can
be left disconnected. Wire as shown in Figure 3.

TEMP. RECEIVER

+–

+–

Figure 3

Models with 4 to 20mA RH Output and a Passive Thermistor Temperature Sensor

The 4-20 mA RH output is identical to the above model with a 4-20 mA temperature

output. The required power supply and wiring of the RH output is the same. The
passive thermistor temperature sensor wires to terminals 3 and 4. Wire as shown in

Figure 4.

TEMP. SENSOR

+–

Figure 4

+
–

+
–

POWER
SUPPLY

POWER
SUPPLY

Checkout

4-20 mA Models:

Verify appropriate supply voltage. The transmitter requires a minimum of 10 and a
maximum of 35 VDC at its connection for proper operation. Choose a power supply

with a voltage and current rating which meets this requirement under all operating

conditions. If the power supply is unregulated, make sure voltage remains within these
limits under all power line conditions. Ripple on the supply should not exceed 100 mV.

Loop Resistance – The maximum allowable loop resistance depends on the power
supply voltage. Maximum loop voltage drop must not reduce the transmitter voltage
below the 10 VDC minimum. Maximum loop resistance can be calculated with the
following equation. Vps is the power supply voltage.

V

ps-10.0

max =

R

Some receivers, particularly loop powered indicators, may maintain a xed loop

voltage to power the device. This voltage drop must also be subtracted from the power

supply voltage when calculating the voltage margin for the transmitter. The following
equation takes this into account. V

R

0-5, 0 to 10 V Output Models:

Verify appropriate supply voltage. The 0-10 V output models require a DC supply of
15-35 V or an AC supply of 15-29 V for proper operation maximum. The 0-5 V output
models require a DC supply of 10-35 V or an AC supply of 10-29 VAC. Both outputs
may be loaded simultaneously with 5 mA.

MAINTENANCE

Upon nal installation of the Series WHT Temperature/Humidity Transmitter and
the companion receiver, no routine maintenance is required. A periodic check of the
system calibration is recommended. The Series WHT is not eld serviceable and
should be returned if repair is needed (eld repair should not be attempted and may
void warranty). Be sure to include a brief description of the problem plus any relevant

application notes. Contact customer service to receive a return goods authorization
number before shipping.

max =

20 mA

rec is the receiver xed voltage.

ps-10.0-Vrec

V

20 mA

This symbol indicates waste electrical products should not be disposed
of with household waste. Please recycle where facilities exist. Check with
your Local Authority or retailer for recycling advice.

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.

Printed in U.S.A. 3/22 FR# 443597-00 Rev. 3©Copyright 2022 Dwyer Instruments, Inc.

Phone: [phone]

Fax: [phone]

www.dwyer-inst.com

e-mail: [e-mail]