Guide
Carbon monoxide and your gas furnace
Carbon monoxide has no smell and no color. In a healthy gas furnace it leaves through the vent pipe; a fault in the burners or the venting can keep it indoors.
If an alarm sounds, or someone feels ill
Move every person and pet out into the open air first. Phone 911 once you are out. According to the Consumer Product Safety Commission, poisoning can feel like a headache with dizziness, or like nausea, weakness, drowsiness and confusion.
Do not go back in to find the source. Once responders clear the house, have the furnace and its venting checked before it runs again.
Source: U.S. Consumer Product Safety Commission, Carbon Monoxide Information Center.
Where it comes from in a heating system
A cracked heat exchanger can let combustion gases into the airstream. A blocked or disconnected vent pipe, or a chimney that no longer drafts, can spill exhaust back into the house. Dirty burners burn poorly and make more of it. A car left running in an attached garage is another common source that has nothing to do with the furnace.
The Colorado statute in brief
Section 38-45-102 of the Colorado Revised Statutes is about houses with gas or other fuel-burning equipment, a fireplace, or a garage built onto the house. Selling one? A working CO alarm has to sit no more than fifteen feet from every bedroom door, unless the building code puts it somewhere else.
Permitted work brings the same duty: putting in a new furnace or other fuel-burning appliance, permitted interior remodels and additions, or creating a new bedroom. Pulling batteries or switching an alarm off is not allowed either, apart from the moments spent testing, servicing or swapping it.
Source: C.R.S. 38-45-102. A summary, not legal advice.
Placement and upkeep
The CPSC recommends battery-operated alarms, or plug-in alarms with battery backup, on every level of the home and outside sleeping areas. Interconnected alarms all sound when one does, which helps in a two-story house. Test them as the maker's instructions say, and replace them when the end-of-life chirp starts or the date on the back has passed.
A yearly look at the furnace
Combustion and venting are both part of a furnace tune-up. If the furnace is old and the heat exchanger is suspect, the repair-or-replace guide covers what comes next.
Cold house? Make the call.
Describe the symptoms and give your street. A heating and cooling business that covers the Fort Collins area, independent of this website, handles everything after that.