Heat/thermal detectors?

[Ira]

Due to a recent flood (which resulted in a lot of open walls), I'm doing a lot of updates to my stuff. One thing I'm considering is replacing my 4-wire SS smokes (4WTAR-B's) with 4-wire SS CO/smokes (COSMO-4W's and a COSMOD4W). Looks like if I do this, I lose the form C relays (each wired to a M1G zone to "show" which smoke triggered) and the thermal sensors that were integral to the smokes.
 
I don't see any way to get the same functionality that was available with the relays, but what about the thermal sensors? Is common practice now to not have thermal sensors near where CO/smokes are located, or are "standalone" thermal sensors being used with/near CO/smokes?
 
I remember from years ago a house that had standalone thermal sensors that were maybe 1.5" diameter, but all the ones I've seen online are the same size as the smokes? Are the smaller ones not any good?
 
Thanks,
Ira

 

[ComponY]

This is kind of off topic, but not at the same time. Look into automated water shut-off valves too. Helps a lot...

 

[ano]

Heat sensors, CO sensors and smoke sensors all have different applications, and are mounted in different ways for maximum protection. While a combination toaster/crockpot/can opener might be helpful in the kitchen, its not the best way to go for safety sensors.
 
Why are heat sensors large like smoke alarms? Because unless they are wireless they are typically mounted to an outlet box, and these are a standard size which determines the heat sensor size.

 

[Ira]

I understand that there are different applications, but some benefit from all three. I read one post that said System Sensor adds thermals to some of their photoelectric smokes to make up for the slightly slower response time. So one could conclude that bedrooms benefit from all three detector types.
 
Maybe this question is better asked like this...
 
From System Sensor, I can get a smoke/thermal detector, a smoke/CO detector, a thermal detector, a CO detector, and a smoke detector. They do not offer a smoke/thermal/CO detector or a CO/thermal detector. My home currently has multiple 4WTAR-B detectors (smoke/thermal with sounder and Form C relay) in the bedrooms and hallway leading to the bedrooms, connected to an Elk M1G, and that is all. They are only a couple of years old.
 
I want to add CO detectors in the bedrooms/hallway, and near fuel burning sources, including in the attic. I also want to add thermal sensors in the kitchen, garage, laundry room, and attic (furnace and water heater are in the attic).
 
Since SS doesn't offer a CO/thermal detector, any location that requires both (kitchen, attic?) will need two devices.
 
So the real question is... for the bedrooms and hallway that already have the smoke/thermal detectors, should I simply add "standalone" CO detectors (like the SS CO1224T* devices) or replace the existing smoke/thermal detectors with the COSMO smoke/CO detectors? If the latter, is it "worth" adding standalone thermal detectors in those areas, or just forget about having thermal detectors in those areas? Cost isn't the concern. It's the WAF with another device on the ceiling/wall.

 

[Del91574]

Get away from the 4 wire devices and use the 2 wire SS devices and module. That frees up a pair of conductors right there unless you're running tandem ring.
 
I swore those units had thermals in them, but don't see them on the cutsheet. Hmmm. Irregardless, you're generally going to see a flaming fire and production of CO on a fire, so might be a moot point.
 
Personally, it's easier to swap detectors than pull cables 99% of the time.
 
Unless you're burning fossil fuels throughout the house, then placing them in kitchens and other areas is somewhat overkill.

 

[Ira]

In this case, pulling cable is very easy, so I don't want to rule anything out based on difficulty/cost of running cable. Lots of attic space above all potential locations. In fact, I would like to make this decision as if it was a completely new install with emphasis on what is best over what is cheapest/easiest, with the limiting factor being the M1G. We are doing a complete remodel due to a major flood event that affected the entire house.
 
Fossil fuel burners... wood burning fireplace in den (including LPG log lighter), range in kitchen, water heater and furnace in attic (both centrally located), clothes dryer in laundry room (near bedrooms). Also have attached garage, but no CO sources in it other than cars. So I guess I have quite a few CO sources, and they are spread throughout the house.
 
Is 2 wire better than 4 wire, or just easier/cheaper?

 

[Del91574]

Seriously, get away from the 4 wire detectors, especially the SS combo units. You're not going to find combo heat/CO detectors no matter what, it's a code issue with the analog circuits and there isn't a market to build intelligent detectors for such a small market.
 
There is no benefit or need to go the 4 wire route route. Plan on adding a pair of outputs and the module with the 2 wire units, take care of the tandem ring and maintenance signal and call it a day. The "need" to know which detector triggered on a loop when it can be determined by the detector itself is a moot point to run an archaic setup. You're looking at, say, for a "typical" 4 BR house, 2 story with basement, 7 smokes to be compliant, maybe 10-12 if you're going overkill. Easy enough to find the unit with the red LED (or blue with CO) upon alarm investigation.
 
If you wire a proper daisy, then it's not easier, it's the same. Connections are simpler and less related components. System operation is also simplified.
 
The mechanical heat detectors should be on a separate loop.
 
You need to think and read the location guidelines for CO detectors, that is going to be paramount for the system design. Installed incorrectly, it's no different than if they weren't there to begin with.
 
Standalone CO should be a homerun and zone unless you pull a minimum of 6 conductors per detector.

 

[TurboSam]

Get away from the 4 wire devices and use the 2 wire SS devices and module. That frees up a pair of conductors right there unless you're running tandem ring.

 
DEL, a point of clarification about this. 
 
I too am looking at the System Sensor COSMO-2W for a two-wire hookup to the Elk M1.  When you "get away from 4 wire devices," you mean just use a two wire, daisy chained, connection to each detector with the 3.9k resistor after the last one, right?  I gather this is called Class B.
 
The reference in the System Sensor wiring diagram to "Loop Style D/Class A Wiring" here, with its dotted lines, was confusing to me until I realized that (I think?) it is just an alternative that some can be employed but is generally not needed in a residence...?
 
Thanks.

 

[RAL]

DEL, a point of clarification about this. 
 
I too am looking at the System Sensor COSMO-2W for a two-wire hookup to the Elk M1.  When you "get away from 4 wire devices," you mean just use a two wire, daisy chained, connection to each detector with the 3.9k resistor after the last one, right?  I gather this is called Class B.
 
The reference in the System Sensor wiring diagram to "Loop Style D/Class A Wiring" here, with its dotted lines, was confusing to me until I realized that (I think?) it is just an alternative that some can be employed but is generally not needed in a residence...?

 
Class A/Style D is a different way of wiring 2-wire devices that offers some advantages in the case of a break in the wiring and also in troubleshooting.  The downside of this method is that it requires 4-wire cable.
 
This paper explains things in more detail.
 
I think DEL advised against using 4-wire devices because of the added complexity of EOL relays for voltage supervision and reversing relays for tandem ring.

 

[Del91574]

There is literally no benefit or need to go with multiple zones of 4 wire fire. I've walked through the inherent issues before. From tandem ring, reset purposes and end user training.
 
The only reason why an installer would  need to run 4 wire fire would be a panel compatibility listing issue or there being too many detectors than what the panel or device supports. In the case of these SS, it's 12 no matter the mix. Same with their MOD2. Both of the SS modules convert a 2 wire loop to 4 wire, so the compatibility issue is a moot point. Not many houses exceed the 12 powered detector number, and if you do, at that point, there's better ways to skin the cat than having 20 odd zones of fire on a system.
 
Class A circuits aren't a necessity. They only benefit is they will allow a conventional system operate with a single fault (trouble). No real benefit for troubleshooting, you're still going to have to pull detectors down and continually split the loop until the fault is located.
 
I'd still recommend a daisy circuit to be wired with 4 conductor for many reasons. Cost is minimal.
 
Run the powered detectors as a single loop. Unpowered detectors as their own or logical grouping. Tandem ring is resolved and locating the detector that generated the alarm is simple. Find the lit LED.

 

[TurboSam]

I'd still recommend a daisy circuit to be wired with 4 conductor for many reasons. Cost is minimal.

 
Thanks, RAL and DEL.  I think I have it now.
 
Part of my problem has been this:  There are 2-wire devices and 4-wire devices and then there are 2-wire devices like the System Senor COSMO module that (even when used with the COSMO 2-wire devices) nevertheless connects to the Elk panel as a 4-wire device.  
 
BUT (and this was my confusion) 2-wire devices daisy-chained behind the COSMO module can nevertheless be wired with 4-wires (the Class A/Style D) with, as noted by RAL, some advantages regarding breaks in wiring--which I assume is one of the "many reasons" to use 4-conductor wire for daisy-chained 2-wire devices....

 

[Del91574]

I think you're thinking of the detectors wrong per se. The detectors are 2 wire, no matter if there's a module or not. They wire to the module like a 2 wire fire loop. Period. How the module connects to the panel is inconsequential. Either you look at tandem ring or you don't. The associated modules just add more options to the host panel. For all intents and purposes, you could just put in 2WTAB's and an RRS/2WMOD2 and have maintenance, tandem ring and that's it or even just put a RRS and call it a day or just the host loop.
 
It's not for wiring the loop as a class A. The effort isn't worth it, not to mention, the purpose of a class A (and wiring methods) require the loop to leave in 2 different directions and not within the same cable, otherwise the loop isn't class A and the benefits (a single wiring fault tolerance) is really not going to exist.
 
I don't see in the docs where the module would do anything other than indicate a local trouble on the module. Can't see where it could do anything but as the host panels usually can't drive both an open circuit and receive a short at the same time. That would need to be looked at.
 
The loop is supervised. You will know of the 3 necessary circuit states.
 
The main reason to run 4/18 is to provide a way to maintain the loop, more so if you add devices rather than having to figure out the end of the loop or pulling to that. Added benefit of spares, but if you have a problem with one conductor on a cable, most likely the entire cable is hosed.

 

[TurboSam]

Thanks, DEL.  
 
I'm finally getting my head wrapped around the options and see that the 2 wire loop gives the necessary supervision info to the panel.