Mysterious hissing sound in CO2 detector
Our 1994 SMB has a CCI 3350 CO detector. When powered up there is an intermitent hissing sound that comes out of the unit which is a bit annoying when trying to sleep. I have run the test procedure using a butane lighter and the alarm works properly. In reading other postings it appears that detectors have a limited life span, but I can't find any info about it. I called the toll free number for CCI but it is disconnected. I assume that they are out of business. On the forum I've seen references to model #3400 which I assume is an upgrade from the previous one. I cant find any info on the SMB website to help. My questions:
1. How long should a CO unit last under normal operating procedures?
2. Since CCI seems gone, are there other units recommened which can be easily mounted in the existing cut out?
3. Would it be easier to simply buy a 9V battery powered unit and not hassle with this?
Thanks for your help.