Horns and strobes are extremely power hungry; internal backup batteries, like the ones inside residential smoke alarms, aren't big enough.
The horns and strobes connected to the common fire alarm system for an apartment building are all wired in - there is no wireless horn or strobe for a common fire alarm system. Whether the horns and strobes are in the halls, or just horns in the bedrooms, all of them are going to have to be wired in.
Old System
The fire alarm system shown in the pictures you sent is around 40 years old. It is no longer supported by the manufacturer. Most probably, the panel no longer achieves the current codes, and has to be replaced. It also probably can't handle the electrical current to operate the bedroom horns.
Unless I'm mistaken, upgrading the fire alarm system to the latest San Francisco requirements involves replacing the fire alarm control panel, replacing almost all the devices in the building, rewiring the whole building for a current Fire Detection and Alarm System, and possibly using off-site monitoring.
Finding a Service Company
No matter who installs the system, the fire department will inspect it to make sure the newly installed system will work.
In other words, no matter what contractor is installing the fire alarm system, there are certain standards that have to be met. Because of these standards, there aren't many shortcuts that any fire alarm installer can make.
Whereas the biggest cost to updating the fire alarm system to the latest San Francisco requirements is the installation of a new fire alarm system, the biggest headache can be caused by a maintenance contractor - make sure the installation contractor is going to provide the service you need for many years to come.
Rewire
Yes, I know. There is a possibility that you don't have to rewire everything, however, be prepared for a complete rewiring project, along with its high cost.
Douglas Krantz
