I've had 2 quotes for a condensing gas boiler to replace our old one. One is for a Vokera and the other for a Viessmann. Anyone have any informed opinions as to which is best?
Opt for the Viessmann, far better IMHO, plus ensure your installer has done his Viessmann installer training course as then he should be able to offer you a full 5 years warranty on the appliance (if not it's only 3 years)
Check that the model is properly sized for your house
Also check the efficiency rating on these models.
Information would be available from manufacturer, also check efficiency rating from the www.sei.ie website.