During our remodel (Man! It's already been six years ago!), the
electrician added smoke-and-fire alarms throughout the house. I really
liked this until recently. The entire first floor's units (six total)
have started randomly beeping. I replace the batteries twice-yearly
(Daylight Savings swings) so it's not that -- especially since the
entire second floor are still silent unless I run a test. I can only
think that each of these beeping units have gotten some dust or debris
on their smoke sensors. Since the electric variety do not have
replicable sensors, how do I go about "cleaning" them -- or would it be
best to simply replace each unit?

Secondly, the Cupertino branch of Home Despot no longer sells First
Alert units. They sell another brand (Pirex, I think). Since I'm
familiar with First Alert products, I tend to shy away from
alternatives. Are there other products that are comparable (both in cost
and quality?)

Many thanks!

The Ranger