tado X and V3+ cannot share a home, and the boiler list shrank
tado states the two generations cannot be used in one home and that X supports a smaller array of modulating boilers. What to check before replacing a single device.
What this means
tado states that tado X devices cannot be added to setups using V3+ and prior, and that the two lines cannot be used in the same home. One account can hold separate Homes for each line. tado also states that X products are compatible with a smaller array of modulating boilers than V3+, so an upgrade is a whole-system decision rather than a device swap.
Equipment and model context
tado X against tado V3+ and earlier
- tado Smart Thermostat X and Wireless Smart Thermostat X
- tado Smart Radiator Thermostat X
- tado Bridge X, Wireless Receiver X, and Heat Pump Optimizer X
- tado V3+ and earlier Smart Thermostat and radiator thermostats
tado's own support guidance on compatibility between product lines. Boiler compatibility for a specific appliance is settled by tado's compatibility checker for the exact model, and nothing here replaces that check.
What this guide covers
- A failed radiator thermostat in a V3+ system, with only X stock available to replace it.
- A plan to add one X device to an existing tado installation.
- A modulating boiler that works with a V3+ thermostat and a proposed move to X.
What changes the answer
- The two lines use different technology platforms and communication standards.
- The X range supports relay and OpenTherm modulating connections rather than every modulating scheme V3+ supported.
Why one device cannot be swapped
tado's position is unambiguous: X devices cannot be added to setups that use V3+ and prior, and the two cannot be used in the same home. The reason given is that the lines sit on different technology platforms and communication standards.
What that rules out in a V3+ house is replacing a failed radiator valve with an X one. The replacement has to be a V3+ device, or the whole installation moves across at once.
tado does allow one account to hold separate Homes for each product line, which covers a second property. It does not create a route to mixing them in a single heating system.
The boiler compatibility narrowed, and where
tado states that compared to the V3+ range, X products are compatible with a smaller array of modulating boilers. The Smart Thermostat X is described as compatible with almost all boilers that support relay connections and modulating OpenTherm connections.
That names the gap. A boiler that modulates through a proprietary scheme rather than OpenTherm may have been supported by a Wired Smart Thermostat V3+ and may not be supported by X, and tado says so explicitly.
Losing modulation is not the same as losing control. A boiler driven by a relay still fires and still heats; what goes is the ability to run at part load against a demand signal, which is where a modulating boiler's efficiency advantage sits. For a house that chose the boiler for that reason, it is a real downgrade hidden inside an upgrade.
What X adds, and the border router requirement
The X line runs on Matter and Thread, which is what makes it interoperable with other smart home platforms in a way the earlier line was not. Thread needs a border router, and tado states that an X setup starts with a Bridge X, a Heat Pump Optimizer X, or a supported Thread border router from another provider.
That is a purchasing consequence rather than a technical footnote. A starter kit exists because at least one of those devices has to be in the house before any X thermostat or radiator valve can reach the app.
On the heating side, tado states that X offers high compatibility with heat pumps through the Heat Pump Optimizer X. For a house planning a heat pump, that pushes the comparison the other way from the boiler question.
How to decide before buying anything
The order that avoids waste is: establish what the heat source is, then check that specific appliance against tado's compatibility checker for the X range, then count the devices that would have to be replaced.
A house with a relay-controlled or OpenTherm boiler and two radiator valves has a cheap migration. A house with a proprietary modulating boiler and nine radiator valves has an expensive one that may end with less control than it started with.
A house planning a heat pump within the life of the controls has the clearest case for moving. The Heat Pump Optimizer X is the device tado points at for that application, and it is also one of the two tado border routers.
| The situation | What tado's guidance implies |
|---|---|
| One V3+ device has failed | Replace it with V3+. X cannot join that home |
| Relay or OpenTherm boiler | The Smart Thermostat X covers almost all of these |
| Proprietary modulating boiler | May be supported by V3+ and not by X. Check the model |
| A heat pump now or soon | Heat Pump Optimizer X is the device tado names |
| Two properties | One account can hold a separate Home for each line |
| Nothing else on Thread | A Bridge X or Optimizer X has to be in the first purchase |
| Property | tado X | tado V3+ and earlier |
|---|---|---|
| Mixing with the other line | Not possible in one home | Not possible in one home |
| Modulating boiler support | A smaller array, relay and OpenTherm | A wider array |
| Heat pump support | High, through the Heat Pump Optimizer X | Not described the same way |
| Network requirement | A Thread border router in the home | Not applicable |
Answering them out of order is what produces a returned box. Only the first can be answered without knowing the appliance in the cupboard.
- Which line is installedX and V3+ cannot coexist in one home
- What the heat source isBoiler control method, or a heat pump
- How that model is supportedChecked per appliance, not per category
- How many devices moveThe whole home migrates or none of it does
Questions people ask about this
Can I use tado X and tado V3+ in the same house?
No. tado states that X devices cannot be added to setups using V3+ and prior, and that the two lines cannot be used in the same home. One account can hold a separate Home for each line, which covers a second property rather than a mixed system.
Is tado X compatible with fewer boilers than V3+?
tado states that X products are compatible with a smaller array of modulating boilers. The Smart Thermostat X covers almost all boilers supporting relay connections and modulating OpenTherm connections, and tado warns that a non-OpenTherm modulating boiler supported by V3+ may not work with X.
Do I need a bridge for tado X?
An X setup has to start with a Thread border router: a tado Bridge X, a Heat Pump Optimizer X, or a supported border router from another provider. Without one, the X devices have no route to the app.
Can I replace one broken tado V3+ radiator valve with an X one?
No. The replacement has to be a V3+ device, because an X device cannot join a home running the earlier line. Moving to X means moving the whole installation.
Is tado X better for a heat pump?
tado states that X offers high compatibility with heat pumps through the Heat Pump Optimizer X, and that device is also one of the two tado units that can act as the Thread border router an X setup requires.
Evidence recordHow this page was checked
official manufacturer support article · checked 2026-09-07
Every technical claim above was written from primary documentation held in the HVAC Bench evidence record: tado technical literature. Where a source limits a definition to certain models, test conditions, or product classes, that limit is repeated here rather than generalised.
- Documentation class
- official manufacturer support article
- Scope of the definition
- tado X against tado V3+ and earlier
- Last checked
- 2026-09-07