System Sensor COSMO-2W - 2-Wire Carbon Monoxide and Smoke Detector Reviews

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Difficult to Use
Submitted on 10/17/2019 Alarm Grid

The System Sensor COSMO-2W is a hardwired combination smoke and CO detector. It is a 2-wire device, but it cannot be used with a specified "reset zone" like a 2-wire smoke detector would. Instead, you have to add a separate System Sensor COSMOD2W i4 Interface Module, a reset relay and a CO trigger relay for it to work. This makes the sensor very difficult to program and genuinely more inconvenient than other hardwired life-safety sensor options. The technicians at Alarm Grid do not enjoy working with this sensor, and we do not usually recommend it to our customers. However, it does work well when configured properly, and it is one-go-all-go, which is pretty nice. This device is not easy to work with, which is why we only give it a 2-Star rating.

Having a smoke detector and a carbon monoxide detector in one single device is a novel concept. At first, it may seem like a good idea. It would reduce the number of sensors you need to add to your system. And since this sensor is one-go-all-go, it seems like a winning situation. But really, it is much more hassle than it is worth. Since smoke detectors and CO detectors require different zone settings, you need two (2) separate zones for the device. But since you only have one sensor, it can't wire to two separate zone terminals, at least not on its own. That is where the COSMOD2W i4 Interface Module enters the equation. This module allows the system to understand that one (1) hardwired sensor is being used with (2) different zones. And then you still need the reset relay and the CO trigger relay.

Setting up and programming the COSMO-2W and a COSMOD2W i4 Interface Module is not a pretty process. Most DIY users will not want to take on this challenge. The easiest option if you are wanting to use hardwired smoke and CO detectors is to use a compatible 2-wire smoke at the designated smoke detector zone (e.g. Zone 1 on a VISTA P-Series Panel), and use 4-wire CO detectors at any other hardwired zone. This will require no special equipment, and everything will function beautifully. And you will still be using the same number of zones as you would with a COSMO-2W!

We do not recommend purchasing both a COSMO-2W, a COSMOD2W i4 Interface Module, a reset relay, and a CO trigger relay and trying to set up this configuration from scratch. It is difficult for DIYers. But if you already have this type of set up configured, and you need to add an additional sensor, then buying a COSMO-2W makes sense. No programming will be required, as it will already be completed. Otherwise, using this sensor does not make sense. We give it a 2-Star Rating.

Good: It works well when set up properly; One-Go-All-Go.

Bad: Difficult to set up; Requires separate COSMOD module, reset relay, and CO trigger relay.

Bottom Line: 2 Stars.