heat detector compatibility question with Radionics panel

I have an old timey D8112 Radionics panel at my new house and want to replace the original heat detectors and smoke detectors. I don't want to replace the security panel at this time given that it works OK. Looking at the compatibility charts for this (and the web site compatibility info at Bosch and System Sensor) I see that they list this info for smoke detectors but nothing about compatibility for heat detectors. Is it safe to assume that I won't have an issue with the heat dectectors from a particular vendor? (I have 7 2-wire heat detectors and a 4-wire smoke detector in one zone with a 12V line) I suspect that is the case given that I currently have Edwards GS heat detectors installed. I'm leaning towards System Sensor detectors because it appears to be a challenge to find Bosch vendors online (and would use the same vendor for all the detectors).

I'd also like to add 3 smoke detectors (for bedrooms for a total of

11). Pubs indicate that there is 10 detector limit for one zone with 2-wire alarms. Not sure why a 4-wire was put on the system for single smoke detector, but my reading indicates that I can hook up more 4-wire alarms without a limitation, so I wanted to confirm that adding 3 4-wire alarms hooked up to the original 4-wire would work fine (and allow me to have 11 detectors in one zone). I'd planned on letting someone else do this part, but having trouble getting someone to do the work without trying to sell me an upgraded Bosch/Radionics security panel.

Thanks for any pointers.

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Virtually any heat detector will work with that system. Heats have a dry contact output, like a light switch. When they detect too much heat or, in the case of a rate-of-rise sensor, when the temperature is rising very rapidly, they close a circuit. The alarm doesn't care what kind of device closes the circuit -- only that it has closed.

BTW, technically, the circuit is always closed. There's a resistor at the end of the circuit which allows a trickle of current to flow all the time. If the current stops flowing due to a cut wire or a device being disconnected, the alarm system will emit a "trouble" tone and/or notify the central monitoring station of the problem. When the detector senses fire the circuit is shorted, allowing lots of current to flow. The alarm senses this and emits a fire alarm (strobes, siren, bell or buzzers, depending on what's installed. If monitored a signal is sent to the station as well.

Reply to
Robert L Bass

The only thing I'd be worried about is the proper temperature rating for the application. (Hint: Don't use a 135 degree in an attic) Also heat and heat with rate of rise are not typically used for life safety applications and that is the primary reason for detectors in a residence.

There is a limit on 4 wire smokes and that is (for the most part) the total draw on the panel output in standby and alarm. You can do the math but the addition you mention should not be a problem if you're describing conditions accurately.

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Heat Detectors do not have to meet compatability requirements because they draw no power and will work on any standard fire panel loop unlike bells horns trobes smokes etc.

Reply to
nick markowitz

As others have pointed out, heat detectors are just normally open switches, and so there are no compatibility issues. Two-wire smokes draw power, and create an alarm over the same wires that deliver power, hence the compatibility concerns. System Sensor smokes will work fine, so long as you don't use two wire smokes with internal sounders and expect them all to sound at once.

However, your heat and smoke detectors should not be wired directly to the

8112. They should be wired to a D125 or D129 module, which is attached to the side of the 8112 cabinet. The D125 is mandatory if you are using two wire smokes. There is no reason you can't mix heat detectors and smokes on the same zone, although you might want to know where the fire is.

Smoke detector reset is done from terminal 8, as I recall, and requires the installation of an extra relay in order for the reset code, command-47, to work. The relay plugs into the circuit board underneath the sheet metal cover.

- badenov

Reply to
Nomen Nescio

Thanks for all of the helpful comments that everyone provided for a novice in this area. This will get me started on replacing the old detectors, and with some additional digging (looking over the system and more reading), then I should be able to add the new smoke detectors to the bedrooms.


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