Hi Valerie,
I was wondering what kind of spacer do you have and how long do you boil it? I have a Micro Chamber and after having it exactly 1 day -- put it in the baby bottle sterilizer. I boiled it for 15 minutes with my nebulizers. And yep, the rubber was melted into a sad little lump. I don't know whether the rubber part on the Micro Chamber is supposed to come off. And if it does, then how do you sterilize that?
I also melted a Flutter. Twice. I am not to be trusted with the baby bottle sterilizer.