Does anyone have a Vaillant System boiler and which thermostats are you using to achieve modulation?","comment":[{"@type":"Comment","@id":"https://www.hotukdeals.com/comments/permalink/51212236","author":{"@type":"Person","name":"themorgatron"},"datePublished":"2023-10-17T19:21:38.000Z","text":"You can buy an Opentherm module for vaillants, they're over £100 though.
Your likely problem will be the boiler cant differentiate between a call for heat or call for hot water. You only want the opentherm adjusting the flow temperature when in heating mode, not hot water.
Vaillants work best with their own controllers."},{"@type":"Comment","@id":"https://www.hotukdeals.com/comments/permalink/51210242","author":{"@type":"Person","name":"TheUrbis"},"datePublished":"2023-10-17T15:10:12.000Z","text":"I believe the later Nest stats support OpenTherm?"}],"commentCount":6,"interactionStatistic":1,"articleSection":"Misc"}