Secondhand KNX devices: worth buying?
KNX actuators and sensors often outlive several homes and renovations — the system is built to last decades. Before you buy a used device, check three things: the address, the documentation, and the support.
How to check a used KNX device before buying
Address
Any KNX device's physical and group address can be rewritten from scratch with ETS — a previous configuration isn't a barrier to using it in your own project.
Documentation
Check whether the manufacturer still offers a manual or datasheet — without it, the device's functions, DIP switches, and ETS parameters are hard to figure out.
Age and support
Find out the device's DT type and whether the manufacturer still supports it with firmware updates — older devices may not support newer functions.
Decide
A basic actuator or sensor from a well-known, stable manufacturer is a safe bet. A specialised or outdated device with no documentation is one to skip.
Why a secondhand KNX market exists at all
An open international standard
KNX isn't one manufacturer's product — it's a certified standard, which is why mixing a certified switch from one brand with an actuator from another is standard practice, not the exception.
Decentralised by design
There's no central controller — every device on the bus has its own address and logic, so one node failing doesn't take down the whole house.
Grows with the building
A line/area topology lets the system expand from a few rooms to a whole building without redesigning it from scratch.
One tool for every device
ETS (currently ETS6) is a manufacturer-independent configuration tool — group addresses are defined there regardless of who made the sensor or actuator.
Certified interoperability
The KNX Association certifies devices for interoperability — pairing one manufacturer's switch with another's relay in the same project is common practice.
Extra security where it matters
KNX Secure (IP Secure and Data Secure) encrypts communication for critical functions, such as door or gate control.
What you get buying new from us
If a used device feels like too much of a gamble, our shop gives you clarity from day one.
- A clear technical spec for every device
- We know whether it fits your specific project
- Free access to our knowledge base
- A partner network if you need help installing
- Honest advice — including what won't work for you
Frequently asked questions
Will a used KNX device's old programming get in my way?
No. Both the physical and group address can be rewritten from scratch with ETS for any new owner — the previous configuration doesn't carry over automatically.
How do I know if documentation exists for a device?
Search the manufacturer's site by model number. If there's no manual or datasheet, figuring out functions and parameters can mean a lot of trial and error.
Will an older KNX device even work with a current ETS version?
Mostly yes — KNX is built to be backward compatible. Still, check the device's DT type and whether the manufacturer still offers support or updates.
Which used devices are the safest buy?
Basic relays, dimmers, and switch sensors from well-known, stable manufacturers — they're simple and well documented. Specialised or niche devices without documentation carry more risk.
Where can I buy new KNX devices if used ones feel too risky?
Check our shop — every device has a clear spec, and our knowledge base is free to use while you decide.
Not sure about that used device?
See the shop — a clear lineup of new, verified KNX devices with straightforward specs.