Review on First Alert CO Detector Alarm with Digital Display and Peak Memory, Battery Operated, CO410 - No Outlet Required by Arun Berry

I bought this because we have a carbon monoxide detector but it's just an alarm. It worked once, so I turned everything off, aired the house, and then carefully restarted everything. It didn't work again this season but I was concerned so I bought this to get an actual measurement. This alarm confirmed that CO levels were rising, but not long enough or high enough to trigger an alarm unless it was particularly cold and the furnace had been running for a long time. We now have a new oven with a confirmed crack in the old heat exchanger.