It must be true. Whenever I am brewing and looking at HBT the likelihood of boil overs seems to increase exponentially. I rarely get a boil over when I am not on HBT! 

This was a while ago, but I would have thought the "problem" would have been more prevalent..![]()
It doesn't cause boilovers!!!!!!
What it seems to cause is spillover in the MLT.
I don't know why, but if I dare get engrossed on HBT, the pump on my HLT works fine while the pump going from my MLT to the BK sloooooooows down so much that my HLT overflows.
It's like that second pump watches me, and keeps the same level and the same amount of wort moving until I stop looking at it.
It doesn't cause boilovers!!!!!!
What it seems to cause is spillover in the MLT.
I don't know why, but if I dare get engrossed on HBT, the pump on my HLT works fine while the pump going from my MLT to the BK sloooooooows down so much that my HLT overflows.
It's like that second pump watches me, and keeps the same level and the same amount of wort moving until I stop looking at it.