I recently upgraded my thermal storage tank for six hundred gallons to twelve hundred. I used EPDM this time instead of a drop in liner (readily available, cheaper ect.) The first tank I had all copper coils, 2-for heat and 1-for domestic HW. As I was having problems with hard water the domestic HW was plugging up so in my new tank I used pex tubing for a coil. Just regular pex no oxygen barrier. My wife complained she could smell hot rubber in the shower, (she complains about everything I do with my wood boiler) So I thought she was crazy??? But I noticed I too could smell it?? Any thoughts? Is it possible? Is it safe? Should I of used pex with oxygen barrier?