SYSTEM SENSOR CO1224T 12/24 volt, 4-wire, system-monitored C02 carbon monoxide detector w/ RealTest Technology

This unit was easy to install (if you ignore the fact that it was waaaaayyy up at the top of the stairs with a high ceiling, and my son had to stand on the very top of the step ladder on the landing!). He duplicated the wire connections off the old unit, same model. However, we kept getting zone errors on our security system. It's an old Elk M-1 system. I looked at the old unit and saw there was a resistor attached to 2 screws, and the new unit did not have a resistor inside. We took it out of the old unit and attached it to the new unit, and the zone error went away. So I searched the reviews and found this: "A resistor is not included with this carbon monoxide detector, but it may be required for sending the end-of-life signal to your panel, depending on your panel type." So be aware, and move the resistor from old to new unit before you start the re-installation.

I had to replace a CO-260 Carbon Monoxide Detector on a wired alarm system. I have included a picture of the old one replaced (I do not believe it is manufactured anymore). This new one is just slightly larger, but it was very easy to take the old one off the wall and put this new one in its place (it fit on the existing mounting screws). All the wiring was the same, as were the labels for the wiring screws. It took me about 15 minutes total. The product had a 5 day arrival window, but it came at the beginning of that window (was shipped from Phoenix to Alabama). I bought this product in January 2025. As you can see from the picture without the cover, the device label says the replacement date is August 2034 (and the manufacture date on my box was Aug 2024). Just sharing some pictures in case it helps others. (I powered down the security system + disconnected the system's backup batteries before doing any work). Only needed a flat head screwdriver to pop the cover off of the new device when wiring / mounting, and used a Phillips' head screw driver to tighten down the wires.

Fair price, fast shipping and easy to install. If you have your home, security system monitored, make sure to contact your alarm company prior to removing the old detector as it will trigger the alarm and require a carbon monoxide test by the fire department. Ask me how I know? Also, once the cover is removed from your old carbon monoxide detector, take a picture of the wires and where they mount so that you can reference it when replacing with the new unit. Overall, very pleased and it took less than 10 minutes to remove and replace.

Arrived timely and in good condition. However, these are supposed to have a date code that is ten years in the future showing 120 months of life remaining. The box even has a red sticker stating, "10 year end of life signal". The one I received has a date code that has only 103 months left. So, I am getting 85% of the life per the date code.

Item delivered as promised and worked as specified.

I'm not dead but it never has gone off sooooo, either there's no carbon monoxide or its not working. How is one to know? Yeah I know buy a can of CO. Was very easy to install. I replaced one I had that reached end-of-life.

I was pleasantly surprised to find the expiration date was 2033. They only last 10 years

Still fresh from the factory, so the replace-by date is still about 10 years, and the “approximately 10 years” end-of-life trouble signal can be expected near then also. A great value.Perfect replacement for a shorter-lived “Costar 12-24 SIR” detector, and easier to connect. Remember this is for DC power, not AC.Note that, although this does send the alarm signal to your panel, with just the four-wire connection, it will not also send the end-of-life signal to your panel (will merely flash red at that point) unless you add a resistor that is not included; the resistor type depends on your panel. Instructions include a warning that says this extra wiring is required by regulations.