Bosch EasyControl on an ATAG boiler: only with the EasyControl Adapter

Short answer: yes, the Bosch EasyControl works with an ATAG boiler, but only with the EasyControl Adapter. ATAG boilers use OpenTherm; the EasyControl itself speaks EMS bus (Nefit/Bosch). The adapter translates and the boiler keeps modulating. This applies to the A Series, i Series (iCon), Q Series, E Series and P Series. With an older Blauwe Engel, check the manual to see whether there is an OpenTherm connection; otherwise only on/off works via the adapter. The set with adapter is then the logical choice.

ATAG by series

ATAG series	Thermostat connection	EasyControl	Spare parts
A Series	OpenTherm	With adapter	A Series parts
i Series (iCon)	OpenTherm	With adapter	i Series (iCon) parts
Q Series	OpenTherm	With adapter	Q Series parts
E Series	OpenTherm	With adapter	E Series parts
P Series	OpenTherm	With adapter	P Series parts
Blauwe Engel	OpenTherm or on/off, depending on year of manufacture	With adapter (on/off if there is no OpenTherm)	Blauwe Engel parts

Always check the protocol in the installation manual of your appliance (search for "OpenTherm" or "thermostat connection"). ATAG fault codes with cause and part: ATAG fault codes.

What you need: thermostat with adapter

If you also want to control radiators per room, choose a set with radiator valves and order the adapter separately.

Step by step: connecting EasyControl

Always read your boiler's installation manual first. If you are unsure about the terminals, have an installer do it.

1. Disconnect the boiler from the power (unplug it) and disconnect the existing thermostat. Bosch specifies that only one thermostat may be connected to the boiler.
2. Connect the EasyControl Adapter with two wires to the boiler's thermostat terminals (the OpenTherm terminals on OpenTherm boilers, the on/off contact on on/off boilers). The adapter needs its own power socket.
3. Connect the EasyControl thermostat with two wires to the adapter (no polarity).
4. Order when switching on: first the thermostat, then plug the adapter into the socket, then the boiler. The adapter searches for OpenTherm for about a minute; if it does not find it, it switches to on/off. To make it search again: unplug the adapter for 25 seconds.
5. Switch the boiler on, connect to your 2.4 GHz Wi-Fi via the Bosch EasyControl app (5 GHz does not work) and follow the setup.
6. After half an hour, check whether the boiler modulates (the flame keeps burning at lower output) and whether the app shows the boiler status.

Things to bear in mind

• On/off via the adapter: the boiler does not modulate and the app reads nothing (no water pressure, no consumption). You do keep remote control, the time programme and presence detection.
• OpenTherm via the adapter: modulating. The water pressure is only shown if the boiler has a pressure sensor and the values have been checked once.
• Nefit Easy Connect or RCC module on an older boiler: remove it first, EasyControl does not work together with it.
• One EasyControl per boiler. You control multiple rooms with the Smart Radiator Thermostats (radiator heads), not with a second thermostat.
• 2.4 GHz Wi-Fi is required; a network that only broadcasts 5 GHz does not work.

Frequently asked questions

Does my ATAG modulate with the EasyControl?

Yes, over OpenTherm via the adapter. Not on an on/off connection.

My ATAG has an ATAG One. Can I switch?

Yes. Disconnect the ATAG One and connect the adapter to the OpenTherm terminals. Only one thermostat may be connected to the boiler.

Can I see the water pressure in the app?

Only if the boiler has a pressure sensor and the value has been checked once. The i Series and A Series have one.

Which terminals do I use on an ATAG?

The boiler's OpenTherm terminals, as indicated in the installation manual. Use the on/off contact only if OpenTherm is not available.

Other brands

• Overview of all brands: does EasyControl fit my boiler?
• EasyControl on a Nefit or Bosch boiler
• EasyControl on an Intergas boiler
• EasyControl on a Remeha boiler
• EasyControl on a Vaillant boiler

All ATAG spare parts at Instalpunt.

Sources: Bosch brochure "Is EasyControl geschikt voor mijn verwarmingssysteem?" (document number 6721867369, October 2024) and the page about the EasyControl Adapter on nefit-bosch.nl. Protocols of other brands: manufacturers' installation manuals. Page updated: 12 October 2026.