OpenTherm Capable Boilers and Controls

OpenTherm Logo
OpenTherm Logo

Shown below are a list of OpenTherm capable / compatible manufacturers and boilers. These OpenTherm Boilers / OpenTherm capable boilers have integrated OpenTherm unless specified otherwise in brackets. For more info on “What is OpenTherm?” at the  OpenTherm Association. You can also see our OpenTherm Capable Controls shown further down the page.

For homeowners: what OpenTherm means see the following page: Modulating ‘A Rated’ Boilers with Smart Modulating Thermostats

What is OpenTherm?

Wikipedia: OpenTherm (OT) is a standard communications protocol used in central heating systems for the communication between a central heating boiler and a thermostatic controller. A two way communications interface, usually in the form of a slave and master device.

As a standard, OpenTherm is independent of any single manufacturer. A controller from manufacturer A can in principle be used to control a boiler from manufacturer B. However, OpenTherm controllers and boilers do not in fact always work properly together. The OpenTherm standard comprises a number of optional features and some devices may include manufacturer-specific features. The presence or absence of such features may impair compatibility with other OpenTherm devices.

OpenTherm History?

OpenTherm was originally created by Honeywell and was sold to the OpenTherm Association on November 1996 for one British Pound. This was no doubt to make the standard independent of any manufacturer.

Modulating Control

Unlike room thermostats that simply tell the boiler when to turn on and off (non modulating graph below) , a modulating control (see modulating graph below) tells the boiler the exact target / set point temperature that is required to be achieved. So as the current temperature starts getting closer to the set point temperature, the boiler starts reducing the flow temperature to match the required demand.

Non modulating thermostat

Modulating Thermostat Graph

OpenTherm Advanced setups

OpenTherm is easier to use on combi boilers. The reason for this is that there is no hot water cylinder to worry about, heating to the correct temperatures as required by legionalla prevention(recommended 60 degrees), as OpenTherm can reduce flow temperatures to below 60 degress. So, on system and regular boilers that have opentherm, in order to also work with hot water cylinders, cylinder temperature reporting must be present in some form. This allows the OpenTherm to fire at high temperature just for the hot water. Note, is is advised that in this setup there is priority to the hot water system, otherwise higher temperatures may reach the radiators when you don’t want them to.

OpenTherm Compatible Boilers

For Manufacturers: If your boiler model is not in this list, please contact us via our contact form or via twitterAdditional Information

Vaillant Ecotec 4XX Series requires additional steps. Please see following thread:

BrandModelAdditional Info

Atag Heating Technology
BrandModelsAdditional Info
AtagiC Economiser

BrandModelsAdditional Info
Baxi100 CombiOpenTherm is Terminals 1 and 2 on the M2 Low Voltage Terminal Block
Baxi200 CombiOpen Therm connecter is labelled 'Bus'
Baxi400 CombiOpen Therm connecter is labelled 'Bus'
Baxi600 CombiOpen Therm connecter is labelled 'Bus'

BrandModelsAdditional Info
DaikinD2CND 24KwCombi Boiler
DaikinD2CND 28kwCombi Boiler
DaikinD2CND 35kwCombi Boiler

Intergas Boilers
BrandModelsAdditional Info
IntergasIntergas Rapid
IntergasIntergas Rapid Plus
IntergasCombi Compact
IntergasCompact Range
IntergasECO RF

Ideal Boilers
BrandModelsAdditional Info
IdealLogic Combi+ Combi C
IdealLogic Combi C24, C30, C35 (via seperate harness kit)
IdealLogic Code Combi (via separate harness kit)
IdealI-mini C24, c30 (via separated harness kit)
IdealVogue Combi C26,C32, C40
IdealLogic + System(Works with Evohome)
IdealLogic + Heat(Works with Evohome)

KD Navien
BrandModelsAdditional Info
Navien NCB

Remeha Boilers
BrandModelsAdditional Info
RemehaQuinta Ace
RemehaQuinta Pro
RemehaGas 110 EcoCommercial

BrandModelsAdditional Info
VaillantEcotec Pro [1]
VaillantEcotec Plus_[1][2]
VaillantEcotec Exclusive[1]
VaillantEcofit Pure_[1]
[1] Using un-official VR33 Module Vaillant OpenTherm and VR33
[2] Ecotec 4XX Series requires additional steps.

BrandModelsAdditional Info
ViessmannVitodens 100W Type WB1A (Connection: X3.3 and X3.4)
ViessmannVitodens 100W Type WB1B (Connection: X21.1 and X21.2)
ViessmannVitodens 100W Type WB1C (Connection: X21.1 and X21.2)
ViessmannVitodens 200-W WB2B 26+ 35 kW (via Expansion Module OT and OT-A8 + _Terminal -10 and +10 are on expansion A8 boiler )
ViessmannVitodens 200-W WB2C, B2HA,B2JA, B2LA (via icm Expander OpenTherm)

BrandModelsAdditional Info
VokeraLinea One (via OpenTherm Kit Part_1221179)
VokeraVision Combi (requires control interface 29450143)
VokeraCompact A (requires control interface 29450143)
VokeraVerve_(heating only mode)
VokeraMynute i (heating only mode)
VokeraVision System (heating only mode)
VokeraUnica i
VokeraVibeSystem boiler
VokeraVision C
Vokera Linea HE
VokeraMynute ASystem boiler
VokeraMynute HE
VokeraUnica HE

ModelsAdditional Info
Ferrolii25 Condensing Combination Boiler
Ferrolii29 Condensing Combination Boiler

BrandModelsAdditional Info
RavenheatHE30S Compact
RavenheatHE98S Combi

Worcester Bosch
BrandModelsAdditional Info
Worcester BoschEMS capable boilers [1]Worcester Bosch and OpenTherm Page
Worcester BoschGreenstar i
Worcester BoschGreenstar i Junior [**]
Worcester BoschGreenstar Si Compact
Worcester BoschGreenstar CDi Compact
Worcester BoschGreenstar CDi Classic [†]
Worcester BoschGreenstar Highflow CDi
Worcester BoschGreenstar 12i System - 24i System [*^]
Worcester BoschGreenstar 27i System - 30i System [*]
Worcester BoschGreenstar CDi Classic System [*†]
Worcester BoschNote: Worcester Bosch OpenTherm information is very limited, please accept this list as capable, but not yet confirmed. There is also no confirmation of hot water working with OpenTherm
[1] Using un-official Nefit Adaptor
[*] Provided optional integral diverter valve is installed
[**] Manufactured after July 2013
[†] Manufactured after 16th January 2007 with software version CF12.10 onwards.
[^] Manufactured after February 2011.

Opentherm Compatible Boilers List Last Updated: 06/10/2018

OpenTherm Compatible Controls

Following are a list of OpenTherm compatible controls. These controls are compatible with Open Therm Capable boilers shown above. Smart Thermostats are listed first. Where an addition tranceiver is required it will be specificied in the brackets. See more info on OpenTherm at the OpenTherm Association.For homeowners: what OpenTherm means see the following post: What is OpenTherm?

Open Therm fact sheet from Honeywell the original creators of OpenTherm:   OpenTherm Fact Sheet

BrandModelReview Page / Info page.Wired / WirelessRadiator ValvesInternet ConnectedHomekitOther
Baxi uSense smart room thermostatNY
Delta DoreTybox Bus OT - 6053056WiredNNN
DraytonWiser Kit 1WirelessYYNHeating Only
DraytonWiser Kit 2WirelessYYNHeating and Hot Water
DraytonWiser Kit 3WirelessYYN3 Zone Support
EsiESRTP4OT Programmable Room ThermostatWiredNNN
Honeywell T4RWirelessNNN
HoneywellLyric T6WiredYYY
HoneywellLyric T6RWirelessYYY
HoneywellEvohomeWirelessYYNRequires R8810
HoneywellCM727WirelessNNNRequired R8810
HoneywellCMS927B1049 Room UnitWirelessNNNRequires R8810
IdealLogic RF7WirelessNNN
IdealTouch Connect Wifi Combi Control 214217
NestSmart Thermostat 3rd GenerationWirelessNYN
NestSmart Thermostat E 3rd GenerationProduct InfoWirelessNYN
RemehaiSenseWired / WirelessNNN
TadoTado Smart ThermostatWired / WirelessYYYRequires Extension Kit
Vokera20050690 Open Therm 7 Day Programmable RF Room ThermostatWiredNNN
VokeraOpenTherm RF Programmer (20050690)WirelessNNN

Opentherm Controls List Last Updated: 16/10/2018

Credits/ Sources / Public Contributors:

Richard Huish

Automatedhome; HenGus, Bruce_Miranda

Steve Todd

John Lockwood

Information Sources:

Page Last Updated: 16/10/2018
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