4-Wire Heat Detectors
If you came here looking for 4-wire heat detectors, then too bad, because 4-wire heat detectors don't actually exist. There are no 4-wire heat sensors that you can integrate with your home or business security system. You might come across 4-wire combination smoke and heat sensors. But you will not find any standalone 4-wire heat sensors. But that doesn't mean that hardwired heat sensors don't actually exist. There are plenty of 2-wire heat detectors that you can easily integrate with a hardwired alarm control panel. Or if you prefer wireless heat detectors, those are available as well.
The most likely reason why people mistakenly believe that 4-wire heat detectors exist is because of the prevalence of 4-wire smoke detectors. When it comes to hardwired smoke detectors for security systems, 2-wire smoke detectors and 4-wire smoke detectors are both widely use. Alarm Grid recommends using 2-wire smoke detectors at a designated 2-wire smoke detector zone (e.g. Zone 1 on a Honeywell VISTA System), as less equipment is involved. You can connect 2-wire smoke detectors at such a zone and not need to use any additional equipment. That makes them the best hardwired smoke sensors for DIY users.
The sole advantage to using 4-wire smoke detectors is that you can use them at any zone, without being restricted by any zoning requirements. This gives you much greater flexibility in selecting a zone. However, setting up a 4-wire smoke detector requires much more equipment, including a separate relay and a power supply. This extra equipment is used for resetting the smoke detector once the fire alarm is cleared. Because of the additional needed equipment, which makes the set up process a bit more involved, most users opt to go with 2-wire smoke detectors if they are trying to integrate hardwired sensors with their alarm systems. But there are some users who understand these challenges and opt to go with 4-wire devices anyway, usually due to the greater flexibility in selecting a zone.
The reason why 4-wire smoke detectors don't exist is because they aren't reset after being activated. Once a heat sensor it triggered, it must be replaced with a completely new sensor. In other words, heat sensors are known as "one-and-done" devices. Therefore, it wouldn't make sense to have a relay and all that extra equipment. And since no resetting logic is required, only 2-wires are needed to facilitate the device. And the good news is that the set up is extremely easy. You just connect the 2-wires from the 2-wire heat detector to an open zone like you would for any other 2-wire device, such as a door and window contact. Then just set up the sensor in programming, and you will be good to go.
Remember, you shouldn't use your 2-wire heat detectors at the designated 2-wire smoke detector zone. While that is technically possible, you typically want to reserve that zone for your 2-wire smoke detector devices. Also keep in mind that you will need to replace your heat sensor with a new one if it is activated for any reason, other than using the designated testing button on the device. Standalone heat sensors are good for areas that are otherwise not suitable for smoke detectors, such as kitchens, bathrooms, garages, attics, and designated smoking rooms. Using standalone heat sensors in those areas can prevent false alarms, which could be caused by excessive humidity and/or dust.