Nobzy – firstly, yours is not a stupid question but it’s rather reflective of a landlord who’s exercising due diligence over the management their properties; good on you!!
In general terms, smoke alarms that were installed within units and elsewhere at the time of a building’s construction become the responsibility of the Owners Corporation upon registration of the strata plan, and those installed post registration in order to comply with the (smoke alarms) Regulation (2006) are the responsibility of the Lot Owner / landlord in terms of maintenance, replacement, and ensuring correct operation at the commencement of each new tenancy, and by the tenant thereafter only with regard to replacing batteries if fitted and to reporting operational faults.
I used the word “generally” (above) because I’m aware that some Owners Corporations (O/C) include smoke alarms installed within Lots post Strata Registration in their annual Fire Safety Inspections. That complicates matters to some degree with regard to rental properties, as those annual Inspections don’t align with the inspections that Landlords / Property Managers are required to make at the commencement of each new tenancy.
In your circumstances, I’d determine who owns the smoke alarms within each of your rental properties, and then continue with the private contractor to annually inspect yours ($ seem a bit high), permit your O/C to annually inspect theirs (which will likely the hard-wired unit), and have your Property Manager/s check all smoke alarms at the commencement of each new tenancy and note that on the Incoming Condition Report/s as they’re required to.
I hope that’s clear….because it is a little complicated.
(Just saw Scotty’s post, but no matter ’cause we’re on the same page).