Carbon Monoxide in a Waukesha County Home: Where It Comes From and What Your Alarm Can and Can’t Tell You

The first sustained cold of the season shuts the windows, starts the furnace for the first time since spring, and fills garages with idling cars on frosty mornings. It is also when carbon monoxide risk rises in Wisconsin homes. The gas has no color, no smell, and no taste, so a household has no warning of its own, and the only thing standing between a leak and a family asleep upstairs is a device on the wall. Knowing where the gas comes from and what that device measures makes it easier to protect the house on purpose instead of by luck.

How a Furnace Makes Carbon Monoxide, and What Keeps It Out of the House

Any flame that burns fuel makes some carbon monoxide. When the flame gets enough oxygen, nearly all of the carbon burns to carbon dioxide, and the small remainder leaves through the flue with the rest of the exhaust. When the flame is starved of air or burns poorly, more of the carbon stops partway, and the amount of carbon monoxide climbs.

The heat exchanger is the barrier that keeps all of this out of your living space. Combustion gases pass through its metal chambers, and the air your blower moves through the ducts passes along the outside, picking up heat without touching the gases. Years of heating and cooling make the metal expand and contract, and a crack can open a path between the two. Dirty burners, a yellow or flickering flame where it should be steady blue, and a flue that doesn’t draw properly all push a furnace toward producing more. Over the Moon’s furnace repair covers unusual odors, CO concerns, and a yellow pilot flame, which are signs that a system needs attention.

Other Sources That Catch Wisconsin Homeowners Off Guard

The furnace is only one source. Several others show up every winter in Waukesha County:

An attached garage is among the most common, since a car left running to warm up releases carbon monoxide that seeps into the house through the entry door, shared walls, and gaps around pipes, even with the garage door open. Warming a car outside costs nothing and avoids the problem.

Tight, well-sealed houses create another. Bath fans, the range hood, and the dryer all push air out of the house, and when the house can’t replace it quickly enough, it pulls air back down the nearest chimney or vent, including the one from a gas water heater or furnace. That reversal, called backdrafting, drags exhaust into the living space.

A blocked vent does the same. Snow drifting over a sidewall vent, an ice plug, a bird nest in a chimney, and a collapsed liner all stop exhaust from leaving.

Generators belong on this list after every ice storm. A portable unit running in a garage, a basement, or beside a window fills the house within minutes. Federal safety guidance calls for running one outdoors and at least 20 feet from the home, with the exhaust pointed away from every opening. A standby unit installed by a licensed electrician, like the whole-home generators Over the Moon installs as an authorized Generac dealer, keeps the unit and its exhaust where they belong.

What an Alarm Measures

A carbon monoxide alarm measures concentration over time, in parts per million, and the standard the devices are built to sets how long it may take to sound at each level. At 70 parts per million, an alarm may take one to four hours to go off. At 150 parts per million, the window narrows to 10 to 50 minutes, and at 400 parts per million it is 4 to 15 minutes. The alarms are deliberately slow at low levels so they don’t go off for every brief, harmless trace, which means a household can be exposed to a modest level for hours before the alarm sounds.

That is why symptoms matter alongside the alarm. Headache, dizziness, nausea, and tiredness that feel like the flu but without a fever, especially when several people in the house feel it at once or the symptoms ease after leaving, point to carbon monoxide. Pets can show symptoms too.

Where Wisconsin Law and Good Practice Put the Alarms

Wisconsin law requires owners to install a working carbon monoxide detector in the basement and on every floor of a dwelling with a fuel-burning appliance, a fireplace, or an attached garage, except in the attic, garage, or storage areas. For newer construction served by electric utilities, the detectors must be powered by the house wiring with a battery backup. Fire-safety guidance also calls for an alarm outside each sleeping area.

Over the Moon recommends CO and smoke alarms that are hardwired to the home’s electrical supply with battery backup and interconnected, so when one sounds, they all do, with at least one on each floor and extras near the furnace, the kitchen, and the garage. Hardwired units with backup can last up to ten years before replacement. When an alarm starts to chirp, the cause is often a dying battery or an aging sensor, a topic Over the Moon covers in its post on why a smoke detector beeps.

What to Do When the Alarm Sounds

Treat every alarm as real until proven otherwise. Get everyone outside into fresh air, including pets, and call 911 from outside. Don’t go back in to open windows or find the cause. Firefighters check the air with meters and clear the house. Before the furnace or any other fuel-burning appliance is run again, a technician needs to inspect it, because the source is still there when the alarm goes quiet.

Inspecting the Source Before the Season Gets Going

Prevention starts with the equipment. Over the Moon’s heating maintenance includes inspecting the heat exchanger for cracks or damage, checking gas connections for leaks, and testing the system’s startup, operation, and shutdown. Its VIP Gold Star Plan adds three visits a year, with a heating and cooling tune-up and an electrical safety inspection, so the equipment and the wiring behind the alarms both get a look.

If it has been a year or more since your furnace was inspected, or the alarms in your house are close to ten years old, contact Over the Moon to schedule a furnace check, or call (262) 232-6480 to have the alarms tested or replaced.