Because carbon monoxide is slightly lighter than air and also because it may be found with warm rising air detectors should be placed on a wall about 5 feet above the floor.
Carbon monoxide detector distance from furnace.
Do not place the detector right next to or over a fireplace or flame producing appliance.
How far should a carbon monoxide detector be placed from a furnace or boiler.
In small homes where 20 foot distance is not possible place the alarm as far away from fuel burning sources as possible.
Homes with attached garages.
Make sure you don t install any co detector too close to any appliance that generates heat.
Keep at least 12 feet 3 7 m distance from the furnace or boiler if otherwise not specified in the user manual.
Keep units at least 20 feet 6 meters away from common sources of combustion particles.
Detector within 10 feet of the internal door to your garage.
If you have an enclosed garage directly attached t o the home then you should also place a.
Feet apart or less then place one in the middle.
The main thing that you are trying to avoid here is false alarms.
If however they are more than 30 feet apart.
You will need more than one detector.
In short you should place your carbon monoxide detector at least 15 feet away from your furnace and this same rule applies to all other combustion appliances.
Keep the area ventilated to prevent unwanted alarms.