Ion vs Photo smoke detectors

["Allan Waghalter" <awaghalter@xxxxxxxxxxx>]

I looked at a Notifier system installed recently by a major local fire alarm
company today and found that they have installed Ion detectors in all of the
classrooms of a school.  I would have spec'd these as photo detectors.  We
had our first cold night last night and they had 3 smoke detectors in
various class rooms go into alarm when the heat came on and burned the dust
off the heat exchangers.  We only use heat here about two or three months a
year (Houston Texas) so dust accumulates in the heat exchangers.  Am I wrong
on the choice of smoke detectors?