Have a good number of existing nest Protect smoke / co2 sensors deployed. Looking in incorporating those into a qolsys system versus buy news smokes / co2s. The man reason is the WAF.
Initial though is to deploy a firefighter module to listen to the T3/T4 sounds of the detectors for smoke or co, and use that as the trip sensor. Thoughts were to get an qi2/qi4 with Honeywell 345 support. And use the FF345 to connect to the panel for co/fire.
If the Nest smoke detectors produce a standard temporal pulse siren, then that should work. If the detectors do not produce a standard siren, or if they announce device names between siren pulses, etc., then it may not function properly.
I have this setup. The 345mhz IQ panel 4 and the 345mhz firefighter. Bought the firefighter from the Surety store (the round 345mhz version, non-encrypted).
I can confirm that it registers alarms for both the Smoke and CO tones on the Nest Protect and works 100% as expected, even with the verbal announcements between tones. Tested a couple times with canned smoke to be sure.
Very happy with this setup. Nest is still the only smoke detector I know that gives you a heads up before an alarm. Has saved me on multiple occasions from going into alarm mode over some toast haha.