Spill switch / down draft problems with Buderus GC124

Hi,

I'm having trouble with my heating system and I'm hoping this community could help. I have a Buderus GC124 that was installed 3 years ago. 2 or 3 times each heating season the spill switch will flip in the middle of the night leaving us without heat. This of course happens on the coldest nights and in particular on very windy or blizzard days. Most recently, it flipped and when I reset it and the boiler fired again, CO detectors started going off in the house, so I'm obviously concerned about the issue.

I had a plumber and chimney specialist come look at the problem and they claimed to have called Buderus who told them this unit should not be installed on an exterior wall and that the unit needed to be replaced. They did not recommend an insulated liner to resolve the issue and said a power vent would void my warranty. I don't see any mention of this in installation instructions and can't find any other information on this anywhere.

This doesn't sound right at all to me but wanted to get another opinion on whether that is true from someone with experience with these boilers. Or any other ideas on what to do to solve my issue?

Thanks,

Joe