MS Electronics E925, E925/24V, E923, E923/24V Product Manual

E925

energy saving controls

Product Guide

Standard Humidistat

E925/24V

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Product Overview

The E925 humidistat offers a calibration-free, high accuracy and high quality solution to humidity
control in an electrical accessory plate form factor.

The E925 regulates to a fully adjustable relative humidity setpoint 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 Live and Neutral input terminals labelled “L” and “N”
(230V AC, 50Hz). On the 24 volt product variant (“/24V”) the same terminals are used (24V AC
or DC) and are not polarity sensitive.

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 relative humidity is sensed to be above the “Setpoint” humidity (use to control

dehumidiers).

• 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

humidiers).

Figure 1 Typical wiring example

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Installation

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

unit.

2. The E925 is designed to be mounted in a 20mm (or deeper) single-gang UK pattress box.

3. Connect the wiring to the terminal blocks on the humidistat as shown in Figure 1 (or any suitably
appropriate form). Make sure to choose the correct output terminals that are suitable to your
application.

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

5. Secure the E925 into the pattress box using the two supplied M3.5 screws.

Operation

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

unit.

2. Adjust the “Setpoint” dial to the relative humidity the room is to be regulated to.

3. Set the “Differential” to the total relative humidity swing either side of the “Setpoint” that the
room humidity is required to keep within.

4. Example of a typical set-up:

Setpoint set to 70% RH, Differential set to 4% RH.
The unit will maintain the relative humidity between 68% RH and 72% RH.

Notes

1. Applying power for the rst time: The output of the humidistat may not switch in response

to humidity for up to 30 seconds after rst powering on. This is normal behaviour due to a

necessary initialisation phase - please wait until this is completed before attempting to test the
humidistat. Normal operation will resume as soon as the initialisation phase has completed.
If the unit has already completed initialisation then short interruptions of power of up to 5
minutes or more will not trigger the initalisation phase and the humidistat will resume normal
operation immediately within a couple of seconds. Power interruptions longer than 5 minutes
may trigger the initialisation phase again.

Technical Specication

Power supply:

Output switch rating: 10A, 250V AC 50Hz (resistive)
Output switch type: Changeover relay (volt-free)
Humidity control: 5% RH to 95% RH
Humidity differential: 1% RH to 10% RH
Sensor accuracy: +/- 3% RH

Sensor drift:

Guarantee: 5 Years
Weight: 97g
Dimensions: 86mm x 86mm x 26.9mm

220V - 240V AC 50Hz (live/neutral)
“/24V” variant: 22V - 26V AC or DC

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

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energy saving controls

Technical Support

For further help or information on this and the other products in the MS Electronics range

visit www.mselectronics.co.uk or call 0333 666 1176.

Alternatively, email [e-mail]

Additional copies of this product guide can be downloaded from our website.

Product Warranty

MS Electronics guarantees all their products against manufacturing defects for

5 years from the purchase date. If your product is found to be faulty, MS Electronics will,

at their discretion, repair or replace the product free of charge.

Note

Any modification or damage to the outer casing of the product, as well as any

damage to the product due to abuse or incorrect wiring may invalidate the guarantee.

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t: 0333 666 1176 f: 0333 666 1436

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MS Electronics reserves the right to alter or change this specification without prior notice.