As a result of radical technical innovation in central heating appliances and air heaters in recent years, modulating forms of regulation are becoming more and more common alongside the usual on/off control. Specific innovative developments include modulation on the basis of room temperature, remote controlled central heating and information readings on the thermostat. This new situation provides a challenge to the manufacturers of controlling devices for the heating industry.

In response to these changes in applied technology, new players (including OEMs and non-traditional suppliers) are trying to get a foothold in this market. This results in many players developing new manufacturer-specific and incompatible solutions for communication protocols between parts of heating systems.

These developments are not in the interest of either the manufacturers of controllers, fitters or end users. The majority of manufacturers would be grateful if a standard communication protocol, such as the current 24 Volt on/off control, would be suitable for use in more advanced control systems, as a widely accepted industry standard would reduce the number of different types of product, thereby enabling better market processes.

The objectives

As the association is a non-manufacturer-dependent platform, all gauge and controller manufacturers may use the protocol. Manufacturers of gauging and controlling devices or boilers may affiliate with the association in order to exert real influence on the development and spread of the protocol. The OpenTherm Association is a non-profit organisation, and its only objectives are to promote the use of the OpenTherm protocol and develop it further. Technical management of the protocol means developing the protocol on the basis of the market’s requirements and the experiences of members. The Protocol Summary has already been expanded to enable the remote setting and reading of appliance functions.

Managing the protocol

The OpenTherm Association manages the communication protocol in both an administrative and a technical sense. This means that the association makes the protocol available to manufacturers of gauging and controlling devices who wish to implement it in their products and are members of the association.

Before products (or the relevant components of them) in which the OpenTherm communication protocol has been applied can actually be brought onto the market, prototypes must undergo a conformity appraisal. The association only issues licences to products that have successfully undergone this test. This procedure is intended to guarantee that only ‘OpenTherm products’ which actually comply with the OpenTherm protocol’s technical specification come onto the market. Further information on procedures for testing, certification and issuing licences is to be found elsewhere on this website.

Members and users

Membership of the association is open to all companies and organisations which are active in the manufacture, distribution or installation of heating systems and components. The majority of current members are directly responsible for implementing the OpenTherm protocol; i.e. the manufacturers of controlling devices such as room thermostats and burner automations. A number of appliance manufacturers who are responsible for implementing the OpenTherm protocol are also members of the association. (Naturally, the said developments are not restricted to Dutch territory as standardisation is of global significance.) A list of members can be found here.

Appliance manufacturers who apply the OpenTherm protocol do not need to be members of the association, as long as they ensure that the modules (burner automats) they use are licensed by the association. As it is important to remain in contact with these manufacturers, the association has set up a user group in order to harmonize market-oriented activities.

The organisation

The association currently comprises about 55 members, mainly manufacturers of controls devices or heating devices. The members meet regularly and collectively determine the association’s policy, the intended developments regarding the OpenTherm protocol and the use of it, and activities based on publicity and promotion. Two committees are active within the association: namely the Technical Committee and the Marketing Committee.

The Technical Committee manages the Protocol Summary and its expansions to additional functions. The Technical Committee also monitors test procedures to guarantee the correct operation of OpenTherm products. The Technical Committee provides technical advice and support to members in implementing the OpenTherm protocol.

The Marketing Committee undertakes permanent market survey and sets action plans aimed at promoting the Association and the protocol within the heating industry.

Y. Lieffering, Association Director


J. de Pauw, Chairman

I. Bloot-Blokland, Marketing & Communication


M. Fokke (Quby), Board Member
M. Broca (Overkizz), Chairman of the Marketing Committee
F. Overweg (Remeha), Board member
D. Kramer (Theben), Board member
A. M├╝ller (Siemens), Board Member
H. Kleiner (Theben), Chairman of the Technical Committee
C. Tuinman (Honeywell), Treasurer

Technical Committee Meeting

The primary objective of the technical committee is to maintain and extend the OpenTherm Protocol Specification. Maintenance and extension is based on new legislation, market trends and new requirements from members. Basically 4 documents are maintained by the Technical Committee:

– The OpenTherm Protocol Specification
– The OpenTherm Application Functional Specification
– The OpenTherm Test Specification
– The Appendix Function Matrix

The latest and older documents can be found in Protocol Specifications

The technical committee organizes at least ones a year a TC meeting. Typical agenda items during these meetings are:
– Review updated documents, proposals
– Discuss and work on changes and extensions
– Discuss compatibility issues

Documents, minutes etc. of the TC meetings can be found in Technical Committee Meeting

Marketing Committee

The Board of the OpenTherm Association identified the need to further promote both the protocol and the Association itself. OpenTherm also needs to keep updated about the market general trends and evolve according to these trends.

The idea of setting a focus group within members came out of this assumption.

The primary objective is to boost the visibility of OpenTherm within the HVAC sector, hence attract potential new members and position the protocol as one of the main standards. A further aim is to even better integrate OpenTherm in a complex and moving market.

OpenTherm Group on LinkedIn

Role of the Marketing Committee:
– Drive the continuous market analysis
– Suggest actions according to the market trends
– Boost the protocol and the association’s notoriety within core target groups through focused
action plans
– Develop required marketing tools and keep them update (ex. Opentherm group on social
– Favor the continuous dialogue between members

Documents Marketing Committee:

Role of the Marketing Committee
Guidelines of the Marketing Committee
Swot analysis