# Smoke and co2 detectors?



## Master Brian (Apr 24, 2009)

I hardwired 4 interconnected smoke alarms in my house. A fifth is waiting on a remodel to finish. 1 in basement utility room. 1 in basement family room. Then main floor hallway and top of staircase to 2nd floor. The 5th is 2nd floor master bedroom. I then have a couple battery alarms, mainly in kids bedrooms. I had a few co2 detectors, but then they went bad, so I bought a new plug in co2 to put in basement in area near furnace and water heater. 

Since they are all getting old, about 10yrs +/-, I am looking at replacing. 

I was thinking of hardwiring the bedrooms, but I'm thinking of buying 3-4 battery powered interconnected for those duties to mix things up. Should I buy a different brand or type for these to mix things up? 

The battery units in looking at are first alert photo electric smoke and electrochemical carbon monoxide. One in each bedroom on main floor. 3 rooms. Then thinking one in a tv room on 2nd floor and maybe a 5th in living room on main floor where a gas fireplace is. All would be mounted on ceiling. 

I'm looking at the equivalent hardwired for those units. Should I swap one or the other for ionization units? Kind of best of both worlds thinking?! If so where you you put each? 

If it matters the house is 100yr old, so lathe and plaster walls, updated wiring, probably some balloon type framing. 

In the utility room the hard wired unit is on ceiling near furnace. 7' ceiling and literally only a foot or two from side of furnace. Is that too close for carbon monoxide detector? That area is just off laundry room with no door between them. I have the stand alone unit in there to monitor things at 5' off ground. 

Regarding gas fireplace, will the ceiling units be fine to monitor that or should I get another stand alone and mount at the 5' height in that room somewhere?


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## huesmann (Aug 18, 2011)

If you're worried about photoelectric vs. ionization, why not get dual sensor alarms?


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## 3onthetree (Dec 7, 2018)

Note CO is carbon monoxide, CO2 is carbon dioxide.
I'm a bit unclear if your "mix it up" concerns battery (but wirelessly interconnected) with wired; or concerns ionization and photoelectric.

If you are remodeling (enough to require permitable work), then the smoke detectors have to be retro interconnected -_ all of them_ together throughout the house, either by wire or wirelessly. I don't believe, but not sure of all new products, that wireless can interconnect with wired units from the same brand. But if you are wiring any of them, wire them all.

You need smoke in every bedroom and right outside the bedroom areas, and each floor. You need CO outside the bedroom areas (at minimum). Your AHJ might have further restrictions, like CO within 15 feet of bedroom door. A suggestion if you want to be efficient in wiring/locations/batteries while also having both ionzation, photoelectric, and CO:

dual smoke sensors everywhere
CO sensors separate - they do not have to be interconnected if ceiling/walls are not exposed during remodeling (note this does not apply to smoke), and do not have to be interconnected with smoke, and allows you to vary placement whereas smoke should be within 12" of ceiling.


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## Master Brian (Apr 24, 2009)

Mis typed co2 for co, not sure what I was thinking. Thanks!

The remodel isn't extensive, just replacing some lathe and plaster on a room with drywall. Easy to wire in the hardwired units at this time and pick up the one on the stairwell to tie into. 

I think I can grab the bedrooms on 1st floor, but not 100% certain. I have one alarm right outside doors for two rooms, just depends on the framing i can snake the wire(s) and I can't recall. The 3rd main floor room i could hard wire. Currently the bedrooms are just smoke battery units with no interconnecting abilities. 

So trying to decide if I should delay replacing the battery units or run a separate system that connects all bedrooms then a hardwired setup for rest of house. Kind of thinking redundant system of two different ones. Maybe that's not logical. 

I hadn't thought about dual sense smoke, I honestly didn't see any come up when looking. If I can get dual sense smoke with co, that's what I'll do.


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## Old Thomas (Nov 28, 2019)

Our code (based on the IRC) requires:
Smoke detectors on every floor level, in each sleeping room, outside each group of sleeping rooms or individual sleeping room if away from the others.
CO detectors in houses built before 1/1/2002, one on each floor level with sleeping rooms within 15 feet of the sleeping room door, one on the level of a fuel burning furnace.
Houses built on or after 1/1/2002, as above but add additional CO detectors on additional floor levels with any fuel burning appliance.
For example, a house with a gas furnace in the basement and sleeping rooms on the second floor, with a gas stove on the first floor, would need CO detectors in the basement and second floor if built before the key date and an additional one on the first floor if built on or after that date.
In my house I have extras. In rental property we provide the minimum prescribed by the code.
I didn’t write the code, don’t shoot the messenger.


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