Just wondering I think my bro is spying on me
as far as I know they have a battery back up get someone who is qualified to look at it!
I'm no firefighter, but the hottest fire I put out was in bootcamp where the staff would start an electrical panel on fire and then I went in and sprayed it with a fire extinguisher. It wasn't very hot.
Most fire hydrants are on private property. Unless the hydrant is no longer active you can be ticketed for parking in front of it.
As you state they are chirping ALL the time, it's not a battery problem. They are in alarm. You have of course pressed and held the reset button on each unit right? Still chirping? See if you can take them down. Turn counter clockwise (as you look at them) and un- plug the harness if it has one. If not, turn off the power and undo the splices. Be sure to cap the hot wire in the ceiling box while the smoke detector is removed. Wait an hour or so and put them back up. If the problem returns replace them. In 4 years I have replaced 3 of my 6 detectors and one of the replacements is acting up! P.S. Not all smoke detectors have battery back up, so if you can't find one, that's why.
MUST CHANGE BATTERY Look harder!