The Viessmann 100s combis I've seen have all suffered from a black material inside the (presumably) rubber flexibles inside the boiler.
We mainly fitted the heat only 100s which haven't got this problem.
I don't know what the material is that forms on the inside of the hoses (making them 'crusty') but when that gets in the plate it is goodnight vienna.
We mainly fitted the heat only 100s which haven't got this problem.
I don't know what the material is that forms on the inside of the hoses (making them 'crusty') but when that gets in the plate it is goodnight vienna.