HVAC emergency in Chicago? Call Bernie's Heating & A/C Service now! Same-day service available for all heating and cooling emergencies.
A working CO detector can provide critical warning when combustion equipment develops a dangerous problem.
Chicago sees 2-5 CO deaths every winter, most from furnace issues. We've been installing CO detectors and inspecting furnaces for CO safety since 1992. Honest - you can install battery detectors yourself. We'll tell you when professional install actually makes sense.
CO is a colorless, odorless, tasteless gas produced by incomplete combustion. You can't detect it without equipment - that's why it's called the "silent killer." We see cases every winter in neighborhoods across Chicago from Irving Park to Bridgeport to Hyde Park.
Often mistaken for flu—but flu doesn't kill you overnight:
We're not here to upsell you. Here's what each type actually offers - you decide what makes sense for your home.
$
DIY Install
Best for: Budget-conscious, renters
Lifespan: 5-7 years (sensor degrades, then replace entire unit)
$
DIY Install
Best for: Most DIY homeowners
Lifespan: 5-7 years
$
+ $ Install
Best for: New construction, whole-home safety
Lifespan: 7-10 years | Chicago code: Required in new construction
$
+ Install
Examples: Nest Protect, First Alert Onelink
Lifespan: 7-10 years
Violation: fines may apply
Plus legal liability if CO incident occurs without detectors installed
Code is the minimum. Here's where we actually put them:
Minimum 3 detectors (basement, first floor near bedrooms, second floor). We recommend 4-5 for full coverage.
We're not going to lie to you - most people can install CO detectors themselves. Save your money unless you need hardwired interconnected systems.
$ per detector
Battery or plug-in units from Home Depot/Lowe's
What you need:
Process:
Honest take:
If you can change a smoke detector battery, you can install a CO detector yourself. We're not going to charge you for something this simple.
$ per detector installed
Hardwired interconnected systems
What's involved:
Worth it when:
When to call us:
Hardwired systems during construction/renovation, or when you want monitoring integration. Otherwise? Save your money and DIY the battery units.
Detectors are your last line of defense. Prevention means addressing the source—your furnace and combustion appliances.
Cracked heat exchanger detection
Annual visual inspection during tune-up ($ catches 3% of older furnaces). Cracks leak CO directly into your home's air supply—this is the #1 CO poisoning source.
Flame rollout switches
Built into your furnace, shuts off gas if CO detected at burner. We test these during tune-ups—failed switches = CO risk.
Proper venting inspection
Blocked vents (birds' nests, ice, rust holes) cause combustion gases to backdraft into home. We check flue pipes, chimneys, PVC vents annually.
Fresh air intake
Provides dedicated combustion air to furnace, prevents backdrafting. Common in tight/weatherized homes. Cost: $$ installed.
Power venting
Motorized fan ensures positive exhaust pressure (gases exit, can't backdraft). Standard on 90%+ furnaces, retrofit option for older units.
CO monitoring systems
Professional-grade detectors integrated with home security system. Monitored 24/7, fire department auto-dispatch. Cost: $$ + monitoring fee.
This is not a drill. CO can kill you in minutes. Follow these steps exactly.
Evacuate immediately
Don't investigate, don't grab belongings. Just leave. Get everyone outside NOW.
Call 911 from outside
Report CO alarm. Fire department has equipment to measure CO levels safely.
Don't re-enter until cleared
Wait for fire department all-clear. CO is invisible—you can't "check if it's safe."
Call Bernie's after all-clear
Fire dept identifies CO, we identify the source (furnace, water heater, etc.) and fix it.
After fire department clears, here's what we typically diagnose as CO source:
Cracked heat exchanger (furnace)
Most common. Requires immediate furnace replacement—no safe repair option.
Blocked chimney/vent
Birds' nest, ice buildup, rust holes. Exhaust backs up into home. Fix: Clean/repair vent.
Backdrafting water heater
Improper venting, negative pressure. Combustion gases pulled back into home.
Car running in attached garage
Even 2-3 minutes. Exhaust enters home through shared walls/door gaps.
False alarms? Rare, but possible (detector malfunction, humidity, chemical fumes). Still treat every alarm as real—evacuate first, investigate after fire dept clears.
Transparent pricing. No hidden fees, no "diagnostic charges."
$
each (you install)
$
per detector installed
$$
per unit installed
Interconnected System (4 detectors)
Hardwired, all units trigger together
$$
Typical Chicago Home (3 hardwired)
Basement, first floor, second floor
$$
Annual CO Safety Inspection
Included in furnace tune-up
$
CO detectors are your alarm system. Preventing CO means addressing the source—your furnace. Here's what we check during annual tune-up:
Heat exchanger integrity (crack test)
Visual inspection + mirror/camera for hidden cracks. Cracks = CO leak.
Burner combustion (proper air/fuel mix)
Yellow flames = incomplete combustion = CO production. Should be blue.
Exhaust venting (no blockages)
Check flue pipes, chimneys, PVC vents for birds' nests, rust holes, ice.
Flame rollout switch operation
Safety switch that shuts off gas if CO detected. We test it works.
CO levels at exhaust (should be <100 ppm)
We measure actual CO output. High readings = combustion problem.
CO detectors tell you there's a problem. Annual inspection prevents the problem from happening.
Cracked heat exchangers (3% of older furnaces)
We catch these during tune-ups BEFORE they leak CO into your home. Once cracked, only option is furnace replacement.
Blocked vents (common in winter)
Ice buildup, birds' nests, rust holes. Exhaust backs up into home instead of exiting. We check/clear vents annually.
Improper combustion (yellow flames)
Dirty burners, wrong gas pressure. Incomplete combustion produces CO. We clean/adjust during tune-up.
Illinois law requires CO detector placement near sleeping areas and on each floor. Fines may apply, but the larger concern is protecting occupants and meeting current legal requirements. Any home with fuel-burning appliances needs working detectors.
Illinois code minimum: Within 15 ft of bedrooms, one per floor. Our recommendation: Near furnace room (basement), near all sleeping areas, near attached garage (car exhaust), kitchen if you have gas stove. NOT in bathroom - humidity causes false alarms.
CO sensors degrade over time. Battery/plug-in units: 5-7 years. Hardwired units: 7-10 years. Check the manufacture date stamped on back - if it's older then that, replace it. Old detectors don't "sort of work" - the sensor just stops detecting CO entirely.
Honest answer - if you can change a smoke detector battery, you can install a battery or plug-in CO detector yourself. Buy one at Home Depot for $ mount it per instructions. Professional installation makes sense for hardwired interconnected systems (requires running electrical wiring) or when you want it integrated with security/smart home.
1) Evacuate immediately - don't investigate, just leave. 2) Call 911 from outside. 3) Don't re-enter until fire department clears. 4) Call us after fire department inspection to find the source. Common sources we find: cracked furnace heat exchanger, blocked chimney/vent, backdrafting water heater, car running in attached garage.
DIY detectors: $ each (you install). Professional hardwired: $ per detector installed. Interconnected system (4 detectors): $$. Smart detector install: $$ per unit. Typical Chicago home (3 hardwired): $$. Honest - only pay for professional install if your doing hardwired/interconnected or can't DIY.
Whether you install detectors yourself or hire us for a hardwired system, don't wait. Schedule an annual furnace CO safety inspection to catch problems at the source. We serve Albany Park, Irving Park, Portage Park, Bridgeport, Hyde Park, and all of Chicago.
Furnace tune-up includes a CO safety inspection. We confirm the price before work begins.