Review on DiversiTech UA 1 Universal Alarm 24V by Evan Burnside

Works great! I hooked it up to my air conditioner's condensate drain switch system. When the transfer pump stops pumping condensate, its reservoir overflows, the internal float switch trips to shut off the pump, the A/C shuts off and this alarm sounds. Also, if the evaporator condensate drain line is plugged in the sump, the sump will overflow and drain into a sump in the return air box. There I installed a second overflow float switch (Little Giant 599123 ACS-2, Condensate Tray Overflow Auxiliary Switch). When it detects a sump overflow, it turns off the air conditioning and sounds an alarm. I installed it right in my return air box just behind the filters. While it's not very loud, I could easily hear it when it was off. The "press to mute" button is handy so you can mute the noise until the issue is resolved.