Replacing 4 wire Smoke and CO detector connected to Alarm System

Hi,
My house is about 20 years old and the smoke and co detectors are original. Are there any considerations on the type of replacements i get beyond them being 4 wire? can I install combo CO/Smoke where I just had smoke?

The smoke detectors are system sensor model 2412. the co detector is Costar model 12E.
Thank you for your help

 

I'm familiar with that brand CO detector as I have replaced them in RV's. Most of the 12xx models run on 12vdc and have a 9v backup battery. They aren't designed to be used in a 4 wire system.

The 12E may be specifically designed for 4 wire use but I didn't see any specs on it. Anyway... the suggested replacement on most of them is every 6 years so you are due. Every 10 years on smoke detectors.

It looks like Costar has a CO only one specifically for your system.... 12-24 SIR.
System sensor offers a smoke/CO combo unit but it looks like it may require an interface module and is dependent on type of panel.
What alarm panel do you have ?

system sensor/Documents/i4Series_Datasheet_CODS303.pdf

 

The box shows FBII XL-2.

I went online with one store that sells 4 wire detectors and they recommended System Sensor CO1224TR which is just CO.

 

I purchased unit DSC FSA-410BST to replace the existing system sensor model 2412 and am hoping for some help working out the wiring. I have attached photos of the backs of the original unit and the replacement.
Guessing I would connect
green wire to first slot marked COM
yellow to second slot marked NO
black to third slot (-)
red to 4th slot (+)

instructions for the new unit are at: http://cms.dsc.com/download.php?t=1&id=16756

I haven't ordered the CO detector yet. Trying to get the smoke detectors replaced first.

Also, any suggestions on how to test?
Thank you

 

Your are showing one smoke detector with a single 4 wire cable.
Are there two) 4 wire cables at the other locations ?
Are you using a supervision relay in the system ? It's discussed in that link you left.
You also need an EOL resistor across C an NO at the last smoke detector in the loop..... or in the case of a supervision relay.... the relay and a resistor.

 

The picture I showed was from the basement. There is a second unit upstairs as well (picture attached) as a CO detector that are all on the same zone on the alarm. The CO detector has the same 4 wires also. I don't have a picture of how the CO was wired as i pulled the wires out with out checking a few weeks ago when it kept going off in the middle of the night. I had placed a new CO Detector next to it in order to verify that it wasn't a real alarm. wires to CO are black red yellow green.

I also added a picture of how its wired into the box. the Smoke and CO are connected to zone 6 which has the green and yellow wires going into it. Is this the resistor and loop you mention?

 

Many times the EOL resistors are put at the panel. The fire loop is one place where the resistor must be at the end of the loop.

Everything on the fire loop is supposed to be wired in a chain from the panel to the first detector, to the second one, to the third one, etc and the resistor goes at the last device. It looks like your detectors are spliced together somewhere as the wiring is not looping in and out. That means there is no real end of loop.

 

PJmax is right. Someone did some "creative" wiring on your smoke loop. Well, it's what you have to work with.

You _can_ move the EOL (preferably with a supervision relay) to one of the devices so that _part_ of your smoke loop is supervised; or you leave it as is and take your chances.

As pictured, the red and black are power for the devices, and the yellow and green are the alarm line, which would go on the alarm terminals on the new devices.

 

I had hoped that this would be a fairly simple swap. I don't feel comfortable that I understand this well enough to move the EOL. From what I read, the EOL helps the system distinguish between a real alarm and a short. Is there anything dangerous in leaving it as is?

Thanks

 

I found a wiring diagram for the system sensor model. It shows that the alarm connections should be to terminals 7&8. I see that in the wiring for my current system, one of the detectors is wired that way but the other one is wired to Com and 8. Does this make any sense or is this a function of the creative wiring?

https://www.systemsensor.com/en-us/D...l_I56-0286.pdf

 

I tried to install the new detectors today and learned a little more about the wiring. Each detector, 2 smokes and 1 CO is on a separate 4 wire line back into the alarm box. And, just for fun, the two smoke aren't even connected in the alarm box. I couldn't get the new detectors working so I reinstalled the old ones. they didn't work either. We tested the voltage and there was no power to either of the smoke detectors. The CO had 13+ volts. When I wen't down to the alarm box, i found the wires had never been connected. These two smoke detectors have been sitting in the house for 19 years doing absolutely nothing!!

Given that I have three separate 4 wire lines back to the box, can you suggest how I can wire them appropriately? According to the wiring diagram, each detector should really have 4 wires in and 4 wires out to the next unit. I don't see how I could do that with out running new wiring.

 

I had hoped that this would be a fairly simple swap. I don't feel comfortable that I understand this well enough to move the EOL. From what I read, the EOL helps the system distinguish between a real alarm and a short. Is there anything dangerous in leaving it as is?
-------------------------------
The EOLR doesn't help the system distinguish between a real alarm and a "short." The control panel looks for 2200 Ohms resistance on the loop. Having the 2.2K EOLR at the end of the line/loop means that all the loop wiring has to be intact for the panel to see the EOLR. So the EOLR is to ensure that loop wires are not broken or cut or come loose from smoke terminals anywhere along the way.
That is the danger of leaving it where it is. If a wire breaks, gets cut, or comes loose, the panel (nor you) won't know about it. It'll sit there fat and happy, unaware of a wiring problem that makes all or part of the fire loop nonfunctional.
====================================================================
I found a wiring diagram for the system sensor model. It shows that the alarm connections should be to terminals 7&8. I see that in the wiring for my current system, one of the detectors is wired that way but the other one is wired to Com and 8. Does this make any sense or is this a function of the creative wiring?
-----------------------
I have no idea what you looked at to make you think the smoke sensor should be connected to terminals 7&8 of your FBII XL2. The smoke sensor manufacturer doesn't know what brand or model control panel the sensor will be connected to, nor which zone of the panel will be used.
Terminals 7&8 are for Zone 5, which _could_ be used for a Fire Zone, but your pictures sure look like the smokes must be connected to Z6 (Zone 6), terminals 8&9, the two terminals that have an EOL Resistor across them in parallel to the loop.
Z5 looks like it has a resistor connected _in series_ with the loop, connected to terminal 8, which would make Z5 unusable for a fire (smoke) zone. So I think your smoke sensors must be all on Z6, terminals 8&9.

There's some confusion about "wired Com and 8". Terminal 8 is a Common (Com) terminal to both zones 5 & 6, so T8 _is_Com. In general, a "Com" terminal is the negative side of a zone loop, "Common" to two zones; or the negative leg of a pair of power loop (+ and -), like terminals 12 & 16. In the vertical row of Zone terminals, terminals 2, 5, and 8 are all Common, meaning that they are all grounded to panel ground and any wire connected to any of them _could_ be connected to any other. (We don't do it that way ((usually)) because it would be hard to keep track of which wires in the panel go where in the house. )
--------------------------------------------------------
I think we need more information about your smoke sensor wiring. First of all, do you have a zone list that confirms that your fire zone (which is your smoke sensor zone) is Zone 6?
Second, the two loop wires (grn and yel) in parallel with the EOLR on Zone 6 (T8 & T9) are not the same two loop wires that show up at the smoke sensor in your picture. There are splices somewhere. Are the grn and yel wires spliced to more wires in/at the control panel, or are there splices at the smoke sensor(s), not shown in your picture?
There may be a way to get your EOLR at the end of your fire loop, but we need to know how your wiring is run, otherwise we're shooting in the dark.
============================================================
I tried to install the new detectors today and learned a little more about the wiring. Each detector, 2 smokes and 1 CO is on a separate 4 wire line back into the alarm box. And, just for fun, the two smoke aren't even connected in the alarm box. I couldn't get the new detectors working so I reinstalled the old ones. they didn't work either. We tested the voltage and there was no power to either of the smoke detectors. The CO had 13+ volts. When I wen't down to the alarm box, i found the wires had never been connected. These two smoke detectors have been sitting in the house for 19 years doing absolutely nothing!!

Given that I have three separate 4 wire lines back to the box, can you suggest how I can wire them appropriately? According to the wiring diagram, each detector should really have 4 wires in and 4 wires out to the next unit. I don't see how I could do that with out running new wiring.
---------------------------------

Well, that answers my previous question about the wiring. No splices, they just aren't all connected.
This should probably have been mentioned before, but smoke sensors and CO sensors shouldn't really be sharing a zone. It might work if you're not monitored by a central station, but if you are monitored, they need to know how to dispatch on a Zone 6 alarm. If the fire department is dispatched on a fire alarm to keep your house from burning down, with heavy equipment to save people trapped on the 2nd floor, and keep the fire from spreading to adjacent houses---and they arrive to find it was a CO alarm, they will not be amused. The fire dep't treats CO alarms differently than they treat fire alarms.
You might consider using that unused "panic" alarm (terminals 8 & 10) for the CO zone, to keep it separate from the smoke sensors.
===================================================
There might actually be a way to supervise your existing wiring with the EOL Resistor, assuming that terminal 12, the smoke sensors power terminal, is Common/Ground, as it is in most panels. I wouldn't do it professionally for a customer, simply because I can't afford the liability for configuring "unorthodox" wiring, even when it works fine. The Fire Marshall takes a dim view of professional techs getting creative, even when the alternative is leaving a system mis-wired. The times I came across this kind of wiring in a customer's home, I documented that that was how I found it, and left it alone.

However, as the homeowner doing DIY repairs, you have more leeway; and as I implied, jacklegging the loop EOLR supervision is better than leaving the resistor on the control panel. And unlike me, there's no documentation that you had your hands on the wiring.

If you can run extra wire to your smokes, I recommend doing it.
If you can't, and want to know how to configure the wiring (creatively) for EOL supervision, let me know. Also if you want to move the CO sensor(s) to the panic zone to keep it/them distinct from the fire zone.

EDIT: Also, one of the EOLR leads in your picture is hovering worryingly close to terminal 10. I'm not sure what the effect would be if it touches, but it's always a good idea to keep wires on terminal x, confined to terminal x, not almost touching terminal y.

 

Basically if they did a home run with 4 conductor to each device location, there are two basic options:

A - You can add a zone expander, and give each device it's own zone (this is really the best solution, but you need to have programming access)

B - You can convert all the smokes to 2 wire devices, but that still leaves you stuck for the CO detector, which can always be a stand alone device.

 

It's been literally a coon's age since I worked on an FBII XL2 panel, but it's my understanding that the panel doesn't support a zone expander _or_ 2-wire smokes. Here's the manual I'm referencing:
https://www.schulersecurity.com/pdfdocs/FBI-XL2.pdf
As far as I knowk, it's limited to the 6 programmable zones and the panic zone, a total of 7 zones.
That's the only reason I suggested the unorthodox wiring configuration: It's better than leaving the EOLResistor across the control panel terminals, IMHO. Assuming, of course, that terminal 16 is Common to ground, along with the zone common terminals.

 

You are right. Somehow I got this one mixed up with another thread (with a NX-8). For the old FBII, the funky wiring trick, or the rigged way it's currently done are really the only practical options.