How many Carbon Monoxide detectors?

In addition to the basement I also put a digital display CO detector in the living room (same room as my pellet stove) and non-display models over the doorways in each bedroom.

Most experts say one is enough . . . if placed outside the bedrooms in the hallway.

To answer the OP's original question . . . it's entirely up to you as to how many you get . . . but I would at least get one more for outside the bedroom . . . possibly another to have one on the main living space if needed.

Many volunteer firefighters on this forum, and many building inspectors citing "code" for your area.

I want to talk about the equipment itself, and human nature as it interacts with this equipment.

Detectors fail, batteries fail, power outages occur and battery back-ups can fail, the sensors themselves can fail, the sensors can vary widely on detecting levels, and dust can settle, altering a detector's ability to do its job. I know of one case in Chicago where the battery operated detector was screaming for perhaps a couple of days until the battery died- while the homeowner was away and did not hear it. They walk inside (the detector was not screaming anymore) and died a few hours later. (This was because of faulty venting on a natural gas furnace)

You can Google detector tests and see videos where one detector is screaming and the other one right next to it does not detect anything.

In Chicago, you can actually borrow equipment maintained by the fire department (or they come to your house for free) and will test smoke and CO detectors.

They are cheap- please get an additional one, or two. Especially since you mentioned a backdraft problem. I am not sure if it is a legacy from the Great Chicago Fire of 1871 or not, but they actually teach this stuff in area schools to this day.

I put one on my lower level. I put 2 on my upper level. One just outside the bedrooms, another on the wall over the stove. All 3 units are a combination smoke / CO detector.

Anybody who doesn't fully trust their CO detector(s), or is concerned about potentially toxic low-level CO buildup that detectors will not register, might consider a pricey meter such as this:
http://www.amazon.com/Test-Instruments-CO71A-Monoxide-Detector/dp/B000MMFAAQ

This could certainly help prevent an occurrence such as the one in Chicago mentioned above. But don't count on it to wake you up in the middle of the night. It won't.

newatthis said:

Thought I'd use it in the basement where the furnace is, and where we already know we have had a backdraft problem with the insert (which shares the chimney which vents the furnace).

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If the alarm sounds in the basement, will it wake you up? If not, get another that will. Better yet, get another even if that one WILL wake you up.

BTW, when you say the insert shares the chimney which vents the furnace, do you mean two separate flues share the chimney, or two appliances share the same flue?

As a parts of the re-model at the house, and to meet code requirements, I have smoke/co in each bedroom hallway and LR/kitchen. 5 total. They are a 10year battery model.

branchburner said:

If the alarm sounds in the basement, will it wake you up? If not, get another that will. Better yet, get another even if that one WILL wake you up.

BTW, when you say the insert shares the chimney which vents the furnace, do you mean two separate flues share the chimney, or two appliances share the same flue?

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I have detectors that communicate with each other wirelessly. If one goes off they all go off. They also announce where the problem was detected, whether it's CO or smoke and, if it is CO, how many PPM.

Our insurance company insisted on interconnected AC wired smoke detectors (not battery only) as a condition of coverage. I was initially annoyed at the few hundred bucks I had to pay for an electrician to run all the wiring. But now I'm happy for the extra peace of mind now that they're installed.

I have 3. One digital ac powered with battery backup downstairs by the insert, then I have 2 basic ones upstairs one in each bedroom, for piece of mind mostly, figure atleast one should go off.

They just became "code" here in Ontario. I took the easiest route and replaced both our smoke alarms with combo co/smoke alarms. Think they were $50 each.

The more the better. Why not?