MS Electronics DH-1/24V Product Manual

Product Guide

DH-1/24V

today, tomorrow and in the future

mselectronics.co.uk

Duct Humidistat

energy saving controls

2

Issue 1.0

Product Overview

The DH-1/24V duct humidistat offers a calibration-free, high accuracy and high quality solution to

humidity control of duct airow in heating, ventilation and air conditioning (HVAC) systems. The unit
is powered from a 24V AC or DC supply and mounts directly on to the outside of the ductwork, with

the probe projecting into the duct.

The DH-1/24V regulates to a fully adjustable relative humidity set-point between 5% and 95%,
combined with an adjustable relative humidity hysteresis (differential) of anything between 1% and
10%.

Product Wiring

1. IMPORTANT: ensure all electrical connections are isolated before commencing any work on the

unit.

2. Power to the humidistat is provided via the 24V AC/DC input terminals. No specic polarity is

necessary on the power connections.

3. A voltage-free changeover relay output capable of switching loads of up to 10A, 250V AC

(resistive) is provided by the humidistat. Connect to your application in an appropriate manner
given the following:

• The Common “COM” terminal is connected to the
Normally Open “NO” terminal when the sensed
relative humidity is above the “Setpoint” humidity.
(Use to control dehumidication equipment,
including air conditioners.)

• Conversely, the “COM” terminal is connected to the
Normally Closed “NC” terminal when the relative
humidity is sensed to be below the “Setpoint”
humidity. (Use to control humidication equipment.)

Figure 1 Typical wiring example (for dehumidication)