background image

3

Issue 1.0

Installation

1. 

Identify a suitable location on the ductwork exterior, preferably where the duct air is cleanest 

(after filtration elements). Mark and drill a 16mm (minimum) diameter hole in the duct through 

which the probe will enter. Any existing hole of up to 25mm is also suitable.

2. 

Remove the lid of the unit and place the probe through the hole, with the unit flat to the 

ductwork and centred in the hole. Mark the four mounting positions (indicated in Figure 1).

3. 

Drill appropriate pilot holes, and secure the unit to the duct with suitable self-tapping screws.

4. 

Adjust the internal controls to suit the installation operational requirements (see below).

5.  Wiring to the unit should run through the preinstalled cable gland. Alternatively, if a direct 

connection to electrical conduit is desired, a suitable conduit connector may be fitted.

 

If using gland:

 For cable outer diameters of 5 to 7.5mm, use the gland as provided. For larger 

cables (up to 13mm), remove the outer nut of the gland, withdraw the rubber insert, separate 

the two parts and reinsert just the outer ring. The other part may be discarded.

 

If using conduit:

 Remove the cable gland by holding the internal locknut steady and 

unscrewing the outer part. Fit an appropriate conduit connector (with M20 thread) in its place.

6.  Connect the wiring to the terminal blocks on the humidistat as shown in Figure 1 (or in any 

suitably appropriate form). Make sure to choose the correct output terminals that are suitable to 

your application.

7. 

Tighten the cable gland or conduit connector onto the outer sheath of the cable.

8. 

Replace the lid and securely tighten the screws.

Operation

1. 

Adjust the “Setpoint” dial to the relative humidity the duct air is to be regulated to.

2. 

Set the “Differential” to the total relative humidity swing either side of the “Setpoint” that the duct 

air humidity is required to keep within.

3. 

Example of a typical set-up:

 

  Setpoint set to 55% RH, Differential set to 4% RH.

 

      The unit will maintain the relative humidity between 53% RH and 57% RH.

4. 

In clean airflow, the unit should require no maintenance. If necessary, the unit may be released 

from the duct and any accumulated debris blown or vacuumed from the probe grille. 

Technical Specification

Power supply:

22V - 26V AC (50Hz) or DC

Output switch rating:

10A, 250V AC 50Hz (resistive)

Output switch type:

Changeover relay (volt-free)

Cable entry:

Pre-fitted M20 gland, for 5 to 13mm dia. round 

cable (remove reducer insert for >7.5mm).

May be exchanged for a M20 conduit connector

Humidity control:

5% RH to 95% RH

Humidity differential:

1% RH to 10% RH

Sensor accuracy:

+/- 3% RH

Sensor drift:

+/- 1.2% RH over 5 years (no calibration 

required)

Probe length (standard):

200mm (sensing element 178mm from base)

Guarantee:

5 Years

Weight:

210g

Dimensions (with standard probe):

109mm x 82mm x 258mm

Ensure the electrical supply to the unit is isolated before making any adjustments.

!

All electrical installation and maintenance must be carried out by qualified personnel 

in accordance with the current edition of the IET Wiring Regulations (BS7671).

!

Reviews: