Thanks for your responses and food for thought.

We had Solar Guys install 3 solar tubes 2 1/2 years ago and had no problems of any kind, I would highly recommend this company and their product. I also had Solar Guys install 2 solar attic fans and although I'm satisfied with the installation the jury is still out on how efficient they are at cooling the attic. If I was doing it again I would probably have temperature controlled power fans installed. The positive side of course is that solar fans cost nothing to run.