chris_x

The Viessmann boiler I was looking at is the B1KF which is a combi. The problem I have found is getting real evidence that a Drayton Wiser will work using opentherm on different boilers. When you talk to the various manufacturers such as Viessmann, Baxi, Ideal and Intergas they all say that they are opentherm compatible but have not tested the Wiser controller on their boiler. The only real data has come from an online supplier of boilers and controllers who say that Wiser does work with Intergas boilers using opentherm. The man has it running in his house. Maybe the answer is to get the Viessmann 200-W which has a 1:17 modulation ratio and run it in weather compensation mode (it does not offer opentherm) and switch it on and off using 240V. The only problem is, will the rooms take much longer to warm up as the central heating water temp is determined by the weather comp curve and not the current room temp? I get the impression weather comp is more suited to 24/7 operation and not having rooms going on and off during the day using smart TRVs.

Has anyone had success using the Drayton Wiser controller to communicate with a combi boiler through the opentherm protocol i.e. to modulate the boiler output? This will exclude Worcester Bosch who use ems and Vaillant. The Viessmann 100-W is supposedly opentherm compatible but does it work in reality?

billt. Did you have any success linking the Viessmann 100 boiler to a Drayton Wiser using opentherm?