I have had the same problem - twice. First time I thought I'd bought a faulty stat, but the second was just as bad. I recently ordered a different stat from Gil-lec, and they've sent me another bloody BMST18, instead of what's on their website. Before sending it back I'm emailing Backer to ask what the specification is.
The one that I ORDERED (code IH230) trips at 96 deg, according to some websites, but the Backer one in my experience trips below 70.
May I suggest you also post a complaint/query on the manufacturer's website at http://backerelectric.com?
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