System Sensor 4WT-B 4-wire, photoelectric i3 smoke detector with a 135 Degree fixed thermal sensor

Exact replacement for my unit. Left original base plate and added new sensor. Alarm system recognized and all is working.

I bought this detector after my 10 year old unit (same mfg and everything!) bit the dust and said there was fire every 3 hours. Not fun at 3, 6, 9 in the morning...you get the idea. So I did some quick research and found this unit to be priced well, and did the purpose of heat and smoke- just what I wanted. Because this was the same mfg, the installation was almost wire for wire- not much needed to change. The instructions were clear just in case you're not comfortable doing this. But I think I had the old one down and the new one up within 7 minutes. And works like a charm! Tested it out with a hair dryer and then with a candle that I blew out...quick response, very pleased!In a nutshell, if you want a smoke/heat detector that is easy to install and reliable. Go with this one!

Bought this to replace the original 20-year old smoke detector. Perfect fit in the original wired mounting base. Sensor reset in alarm system cleared the trouble code.

Perfect replacement for System Sensor model # 2112/24TS 4-wire PhotoElectronic smoke detector. Easily removed old unit and rewired the new unit by connecting red wire to + in terminal, single black wire to - in/out terminal, two black wires to no terminal and green and white wires to com terminal. Tested the newly installed unit by inserting allen wrench into recessed test switch and applied heat from a hair dryer. Both test sounded the alarm. Unit is correctly wired and installed when the green LED light is blinking.

This purchase was to replace an inoperative sensor. It works as design and was easy to install. I was disappointed the device didn't come with mounting screws, but luckily I retained the old one. I've had this device for over 2 months and there are no issues.

Great product!

easy to understand instructions. had to drill 1 new 1/4 inch hole for the connecting wire. old mounting holes fit just fine. tested ok on first try. cost a lot less than the original sensor that was 20 years old. inflation may be rampant elsewhere, but System Sensor prices are going the other way. thank you System Sensor for a nice product at a really good price. lucianphoenix, retired electronics engineer.

This smoke head works great with my Xfinity alarm system due to them no longer sell smoke detectors.