Whether the air is 'forced' across the tubes or 'drawn' across the tubes makes no differnce since it is the temperature of the air that makes the difference and it is the same in both cases.
At any rate, if you can't hearthe fan then the amount of air flowing isn't high enough to be any 'danger' to the tubes, forced or induced.
Salut, Bob P.
At any rate, if you can't hearthe fan then the amount of air flowing isn't high enough to be any 'danger' to the tubes, forced or induced.
Salut, Bob P.