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Secure Z-Wave Room Thermostat with built-in relay - SRT323

4 Stars 1 product review
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Product Description

SRT323 is designed to be used as part of a Z-Wave smart home network, enabling the temperature set point to be controlled via most networks. Through a Z-Wave gateway, the heating can be controlled remotely, via the Internet. This thermostat is a single-box solution with integrated relay that includes time-proportional integral (TPI) software and interoperable Z-Wave radio.

It can be used as a direct replacement for existing thermostats, without the need for wiring changes, while the TPI software optimises boiler firing to help maintain the set temperature without 'overshooting'. TPI controllers have been shown to provide considerable energy savings, compared with traditional heating controllers. The interoperable Z-Wave radio enables you to remotely change the set point, read the temperature or receive alerts when used with a Z-Wave controller, allowing remote control of heating from anywhere with an Internet connection. You no longer have to worry about returning to a cold house.

Note: this thermostat has a built-in relay, and is therefore not intended to directly associate with a Z-Wave relay via mesh radio. For such applications, the SRT321 should be used. This provides the same functionality, but without a relay, allowing it to be directly associated with a receiver.

Key Features

  • Z-Wave ® mesh radio integration with home control networks
    • No wires
    • Quick and easy to install
    • Compatible with most Z-Wave gateways and receivers
    • Z-Wave Thermostat Device Class using Thermostat Setpoint Command Class
  • Integrated relay
    • No need for external receiver
  • Sophisticated time proportional integral (TPI) algorithm
    • Improves energy efficiency
    • Consistent and accurate control, while minimising temperature overshoot
  • Battery operated
    • Uses 2 x AAA cells, with battery life in excess of two years

Domestic gas or oil-fired central heating and hot water systems

Its integrated 3-ampere relay makes SRT323 ideal for controlling gas or oil-fired central heating systems. TPI software significantly improves the efficiency of the boiler by preventing short-cycling, while maintaining consistent comfort.

Combi boiler control

The single-channel relay incorporated within the SRT323 enables it to controla combi boiler directly, while the TPI software ensures the most efficient operation. It requires only minimal wiring between the boiler and the relay.

Zone control

SRT323 is ideal for controlling individual heating zones and is very easy to install. It is battery powered and communicates using mesh radio, so it only needs control wiring. This gives maximum flexibility in choosing the best location to mount the device, and makes it suitable as a direct replacement for existing mechanical (bi-metallic) thermostats.

New systems

The flexibility and ease of positioning, due to battery power and wireless communications, make SRT323 ideal for new installations.

Replacement of conventional room thermostats

SRT323 fits on to the industry standard 6-pin wall plate, so it can be fitted as a drop-in replacement for most other existing thermostats. 

Technical Specifications


Purpose of control

Electronic room thermostat +RF (independently mounted)

Contact rating

3 (1) A, 230 V AC

Contact type



3 V DC (2 x AAA alkaline batteries)


Action Type 1B

Operating time limitation


Software Class

Class A


Mesh radio type


Operating frequency

868.42 MHz (EU)

Receiver Category

Category 3

Power Class

Class B

RF range

≈100 m, line of sight


Dimensions (W x H x D)

86 mm x 86 mm x 36 mm

Case material

Flame-retardant thermoplastic

Ball pressure test temperature

75 °C


Industry standard 6-pin wall plate

Environmental impulse voltage rating

Cat II 2500V

Enclosure protection


Pollution degree

Degree 2

Operating temperature range

0 °C to +40 °C


Design standards

EN 60730-2-9


ETSI EN 300 220-2

ETSI EN 301 489

What's in the box

  • SRT323 thermostat
  • 2 x AAA batteries (long life)
  • Standard 6-pin wall plate
  • User and installation instructions
  • ErP Directive Class Declaration Sheet


View the manual for this product online - PDF - Opens in new window

Product Reviews

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  1. Works well once installed 4 Star Review

    Posted by on 9th Jan 2019

    The installation manual is very poor and lacks in details. The various settings are not well explained nor how to deal with errors when the Z-Wave controller don't want to take charge of the thermostat.

    Since it is a wired thermostat with built in relay it would be better if it was run of the mains wires rather than batteries which must be replaced at some uncertain point in the future or the house goes cold.

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