Minco AH440 Instructions Manual

AH440 Humidity and Temperature Transmitter

Installation and Operating Instructions

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Description

Model AH440 is humidity / temperature assembly consisting of separate 2-wire temperature compensated
humidity and temperature transmitters, as well as a rugged sensing probe. The assembly utilizes a Honeywell
HIH series monolithic IC humidity sensor, which provides excellent stability and chemical resistivity. The
humidity transmitter converts the humidity sensor’s signal into a 4 to 20 mA DC current, which changes
proportionally from 4 mA at 0% RH to 20 mA at 100% RH. The leads that supply power also carry the current
signal. The additional temperature transmitter provides a second 4 to 20 mA DC output where the current
changes from 4 mA at the lowest temperature of the range, to 20 mA at the top of the temperature range.
The range of the temperature transmitter can be re-scaled via dip-switches. These transmitters have non­interacting, field adjustable zero and span pots and are available in duct mount, wall mount, outside air (OSA),
and space mount configurations.

Specifications

Output(s):

Sensing Element:

Ambient Temperature:

Operating:

Storage:

Supply voltage:

Voltage effect:

Loop resistance:

Accuracy:

Humidity:

Temperature:

Adjustments:

Time Constant:

Connections:

Weight:

Minimum output current:

Maximum output current:

Humidity: 4 to 20 mA DC = 0% to 100% RH.
Temperature: 4 to 20 mA DC over specified range.

Humidity: Capacitive monolithic IC.
Temperature: 1000 ohm platinum; 2 lead RTD.

Room: -10 to 150°F (-23 to 65°C), non-condensing.
Duct/Wall/OSA: -10 to 185°F (-23 to 85°C), non-condensing.
Room: -58 to 150°F (-50 to 65°C), non-condensing.
Duct/Wall/OSA: -58 to 185°F (-50 to 85°C), non-condensing.

9.5 to 35 VDC, non-polarized.
.001% of span/volt from 9.5 to 35 VDC.
The maximum allowable resistance of the signal-carrying loop, including

extension wires and load resistors, is given by this formula: R

9.5)/0.02 AMPS. For example, if supply voltage is
24 VDC, the loop resistance must be less than 725Ω.

Includes temperature, linearity, hysteresis, repeatability, and voltage effects.
±1% from 10% to 80% RH @ 25 to 35°C or ±2% from 0% to 90% RH @ 25°C.

(±3% from 0% to 90% RH @ 15 to 50°C).
(±5% from 0% to 90% RH @ 0 to 82°C).
± 0.75% of span for 32 to 122°F ambient
± 1.5% of span for -13 to 185°F ambient
Zero and Span field adjustments, non-interacting.

50 seconds in slow moving air.
Screw terminals (22-14 AWG wire).

1.77 lb (0.81 kg).

3.5 mA.
23 mA.

loopmax

= (V

supply

-

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Installation Do’s and Don’ts
Do:

• Check the label and verify the model number of the unit.

• Confirm the required power and signal wires are available at installation site.

• Avoid electrical interference with other signals by using twisted pair wiring. Do not run signal leads

near or parallel to line voltage or other power leads.

• Mount the unit on an interior wall located away from air drafts coming from forced air heating/cooling
vents, within the wall and/or the wiring conduit.

Don’t:

• Do not touch or manipulate the sensors.

• Do not expose the sensor to direct light during installation. This causes a false reading. Should this

occur, shade the sensor. It will self-adjust and yield an accurate reading in less than two minutes.

• Do not expose the sensor or transmitter to static electricity. This device incorporates CMOS
components which are vulnerable to damage via static charges.

Mounting

Installation of the AH440 consists of mounting the transmitter and connecting it to power.

Duct/Wall/OSA Mounting: Models AH440D… AH440O… AH440W

1. For the duct mount model AH440D only, drill ½” hole into sheet metal of duct. (Probe is 3/8” in
diameter.)

2. Remove the rubber cap from the end of the probe.

3. Using the fold-out tabs on bottom of housing, mount housing to sheet metal.

4. Remove transmitter cover and connect power wires to the transmitter by 2 screw terminals located
near the edge of the circuit board (Figure 2). Power supply must not exceed 35 VDC.

5. Re-install cover.

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