This Could Save Your Life
Carbon monoxide is called “the silent killer” for a reason.
It has no smell. No color. No taste. No warning. You can’t detect it without an alarm. By the time you feel symptoms, you may be too confused to save yourself.
Every year in the United States:
- 400+ people die from unintentional CO poisoning
- 100,000+ visit emergency rooms
- 14,000+ are hospitalized
- Your furnace is a leading source
This isn’t meant to scare you—it’s meant to save you.
If you have a gas furnace in your Bay Area home and you haven’t had it professionally inspected in the last 12 months, you are at risk.
This article will explain why annual furnace maintenance isn’t just recommended—it’s absolutely non-negotiable for your family’s safety.
What is Carbon Monoxide?
The Science (Simple Version)
Carbon monoxide (CO) is a toxic gas produced when fuel burns without enough oxygen.
Your gas furnace burns natural gas:
- Perfect combustion: Natural gas + oxygen = carbon dioxide (CO₂) + water vapor + heat
- Imperfect combustion: Natural gas + limited oxygen = carbon monoxide (CO) + other byproducts
When your furnace is working correctly:
- Combustion happens inside the sealed heat exchanger
- CO and other gases exit safely through the flue pipe
- Only clean, warm air enters your home
- You are safe
When your furnace has problems:
- Cracks in the heat exchanger
- Blocked flue pipes
- Improper combustion
- Backdrafting
- CO enters your living space
- You are in danger
Why Carbon Monoxide is Deadly
How it kills:
- You breathe in CO
- CO binds to hemoglobin in your blood (250x stronger than oxygen)
- Oxygen can’t attach to hemoglobin
- Your organs are starved of oxygen
- Brain damage, organ failure, death
The terrifying part:
- Early symptoms feel like the flu
- Many victims dismiss symptoms
- CO causes confusion, preventing you from recognizing danger
- People literally die in their sleep, never knowing
- Entire families can be poisoned simultaneously
Time to unconsciousness at various CO levels:
- 50 ppm: Headache after 8 hours
- 200 ppm: Headache, dizziness after 2-3 hours
- 400 ppm: Life-threatening after 3 hours
- 800 ppm: Unconsciousness after 45 minutes, death within 2-3 hours
- 1,600 ppm: Headache and nausea within 20 minutes, death within 1 hour
- 3,200 ppm: Headache and nausea within 5 minutes, death within 30 minutes
- 6,400 ppm: Unconsciousness after 1-2 minutes, death within 10-15 minutes
- 12,800 ppm: Immediate unconsciousness, death within 1-3 minutes
For reference: A properly working furnace produces 0 ppm in your living space.
How Your Furnace Can Produce Deadly CO
The Heat Exchanger: Your Critical Safety Barrier
What it is: The heat exchanger is a metal chamber inside your furnace where combustion occurs. Think of it as a metal box with a crucial job:
- Inside the box: Gas burns, creating heat and combustion gases (including CO)
- Outside the box: Air from your home flows around it, getting heated
- The exchange: Heat transfers through the metal wall
- The separation: Combustion gases stay inside, exit through the flue
- Your safety: Clean warm air goes to your home, deadly gases go outside
When the heat exchanger cracks:
- The barrier is breached
- Combustion gases mix with your home’s air
- CO enters your ductwork
- Distributed throughout your home
- Every room becomes a danger zone
Why Heat Exchangers Crack
1. Age and Metal Fatigue (15-20 years)
- Constant heating and cooling cycles
- Metal expands when hot, contracts when cold
- Thousands of cycles create stress
- Microscopic cracks form and grow
- Eventually: Complete failure
Bay Area consideration: Coastal homes have accelerated corrosion from salt air. San Francisco, Pacifica, Half Moon Bay furnaces may develop cracks earlier than expected.
2. Delayed Ignition (Booming Sounds)
- Gas builds up in combustion chamber
- Finally ignites in small explosion
- BOOM sound when furnace starts
- Each boom stresses the metal
- Creates and widens cracks
- Never ignore booming sounds
3. Improper Combustion
- Wrong air-to-gas ratio
- Produces hotter flames
- Overheats heat exchanger
- Accelerates cracking
- Creates hotspots in metal
4. Dirty Burners
- Dust and debris on burners
- Uneven flame pattern
- Localized overheating
- Metal weakens and cracks
5. Restricted Airflow (Dirty Filters)
- Clogged filter restricts air
- Furnace can’t cool properly
- Heat exchanger overheats
- Metal fatigues faster
- Cracks develop
6. Poor Maintenance
- All of the above go unchecked
- Problems compound
- Small issues become catastrophic
- Crack develops and grows
Other CO Risks from Your Furnace
Beyond cracked heat exchangers:
1. Blocked Flue Pipe
- Bird nests in vent pipe
- Damaged/collapsed vent
- Ice blockage (rare in Bay Area)
- CO backs up into home
2. Backdrafting
- Negative pressure in home
- Exhaust fans pulling air
- Flue gases pulled back inside
- Common in tightly sealed homes
3. Improper Venting
- Wrong vent pipe material
- Incorrect slope
- Too long or too many turns
- Gases don’t exit properly
4. Failed Draft Inducer
- Motor pulls exhaust gases out
- When it fails, gases linger
- Can spill into home
- Safety switches should prevent this (if working)
5. Flame Rollout
- Flames extend outside combustion chamber
- Usually due to blocked vent or combustion air
- Indicates serious problem
- Immediate danger
Carbon Monoxide Poisoning Symptoms
Early Warning Signs
Mild exposure (50-100 ppm for several hours):
- Headache (most common first symptom)
- Dizziness
- Nausea
- Fatigue
- Shortness of breath
Key indicator: Symptoms improve when you leave home and return when you come back.
Why this matters: Many people think they have the flu and stay home resting—exactly where the CO is poisoning them.
Progressive Symptoms
Moderate exposure (200-400 ppm):
- Severe headache
- Confusion
- Vomiting
- Chest pain
- Visual disturbances
- Weakness
Severe exposure (400+ ppm):
- Loss of consciousness
- Seizures
- Cardiorespiratory failure
- Brain damage
- Death
Who is Most Vulnerable?
High-risk groups:
- Infants and young children (breathe faster, bodies smaller)
- Elderly (weaker systems)
- Pregnant women (affects fetus)
- People with heart disease (less oxygen to heart)
- People with anemia (less hemoglobin available)
- Pets (especially birds and small animals)
Terrifying reality: Healthy adults can be poisoned while sleeping. You may never wake up.
Real Bay Area Carbon Monoxide Incidents
Case Study 1: The Walnut Creek Close Call (2019)
The family:
- Mom, dad, two kids (ages 7 and 10)
- 15-year-old furnace
- Never had professional maintenance
The incident:
- Cold snap in January
- Furnace running constantly
- Family noticed headaches after 2-3 days
- Blamed it on winter colds
- CO detector finally alarmed at 3 AM (165 ppm)
- Evacuated immediately
- Called 911
Fire department findings:
- CO levels throughout home: 150-180 ppm
- Heat exchanger had 3-inch crack
- Had been leaking CO for weeks
- Family experiencing chronic low-level poisoning
Medical outcome:
- All four family members treated for CO poisoning
- Children hospitalized overnight
- Full recovery fortunately
- Could have been fatal if not for detector
The cost:
- Emergency room visits: $8,400
- Lost work time: $3,200
- Emergency furnace replacement: $6,800
- Emotional trauma: Priceless
What an annual tune-up would have cost: $200 and would have caught the crack before it became dangerous.
Father’s quote: “I thought maintenance was optional. I’ll never skip it again. We almost lost our kids because I wanted to save $200.”
Case Study 2: The San Francisco Tragedy (2016)
The victims:
- Elderly couple, ages 73 and 76
- Living in Richmond District
- 22-year-old gas furnace
The incident:
- Found deceased by daughter during wellness check
- No CO detector in home
- Autopsy revealed CO poisoning
- Fire department inspection found severely cracked heat exchanger
- Estimated CO levels: 800+ ppm
- Died in their sleep
Contributing factors:
- Furnace never professionally maintained
- Heat exchanger had multiple large cracks
- Flue pipe partially blocked
- No carbon monoxide detector
This was 100% preventable.
Case Study 3: The Oakland Rental (2021)
The situation:
- Rental home, three young professionals
- Landlord claimed furnace was “recently serviced”
- No documentation provided
The incident:
- Tenant experienced severe headaches, dizziness
- Dismissed as work stress
- CO detector (tenant’s own) alarmed at 245 ppm
- Evacuated, called fire department
- Heat exchanger crack found
- Landlord had NOT actually serviced furnace in 4+ years
Legal outcome:
- Landlord fined
- Required to install CO detectors (California law)
- Tenants’ medical bills covered
- Furnace replaced
California law: Landlords MUST provide working CO detectors in all rental units with fuel-burning appliances or attached garages.
Case Study 4: The Silent Survivor (Redwood City, 2023)
The victim:
- Single woman, age 42
- Working from home
- Experiencing “mystery illness” for 2 months
Symptoms:
- Chronic headaches
- Fatigue
- Nausea
- Dizziness
- Difficulty concentrating at work
- Multiple doctor visits, no diagnosis
Discovery:
- New boyfriend visited with CO detector on keychain
- Detector alarmed immediately (88 ppm)
- Called fire department
- Small crack in heat exchanger
- Chronic low-level exposure for months
Medical impact:
- Neurological testing revealed CO damage
- Memory issues persisted for 6 months
- Lost job due to cognitive impairment
- Eventually recovered, but long road
The invisible danger: Low-level chronic exposure can cause subtle symptoms that mimic other conditions. Always consider CO if you have unexplained symptoms at home.
Why Annual Furnace Tune-Ups Are Non-Negotiable
What Happens During a Professional Inspection
Our comprehensive safety inspection includes:
1. Heat Exchanger Inspection
- Visual inspection with camera
- Look for cracks, rust, corrosion
- Check welds and seams
- Infrared imaging (some inspections)
- This is THE most important safety check
2. Combustion Analysis
- Measure oxygen and CO levels in flue
- Verify proper combustion
- Check air-to-gas ratio
- Identify problems before they become dangerous
3. Carbon Monoxide Testing
- Test CO levels in exhaust
- Test for spillage into home
- Verify draft (negative pressure pulling gases out)
- Ambient air testing
4. Burner Inspection and Cleaning
- Clean burners thoroughly
- Inspect flame pattern
- Look for debris or blockages
- Ensure even combustion
5. Ignition System Check
- Test igniter
- Verify proper ignition timing
- Check for delayed ignition (booming)
- Ensure reliable starts
6. Venting System Inspection
- Check flue pipe for damage
- Verify proper slope
- Look for blockages
- Ensure secure connections
- Check vent cap outside
7. Safety Controls Testing
- Flame rollout switch
- High limit switch
- Pressure switches
- Gas valve operation
- All must function properly
8. Blower and Airflow
- Measure airflow (CFM)
- Check for restrictions
- Clean blower wheel
- Verify proper speed
9. Electrical Connections
- Inspect all wiring
- Tighten connections
- Test capacitors
- Measure voltage and amperage
10. Filter and Ductwork Check
- Inspect air filter
- Check for duct leaks
- Verify return air adequate
- Ensure proper airflow
Time required: 60-90 minutes for thorough inspection
Cost: $150-$250
What you get: Peace of mind that your furnace isn’t poisoning your family
What We Find During Inspections
Statistics from our Bay Area inspections (2023):
Out of 847 furnace tune-ups we performed:
- 23 furnaces (2.7%) had cracked heat exchangers requiring immediate replacement
- 67 furnaces (7.9%) had dangerous CO levels in flue (combustion issues)
- 142 furnaces (16.8%) had partially blocked vents
- 289 furnaces (34.1%) had delayed ignition issues
- 412 furnaces (48.6%) had dirty burners affecting combustion
Translation: Nearly 1 in 3 furnaces we inspected had a safety issue that could lead to CO poisoning if left uncorrected.
These homeowners thought their furnaces were fine. They were wrong.
The Cost-Benefit Analysis
Annual tune-up cost: $200
What it prevents:
- ❌ Carbon monoxide poisoning: Priceless (your life)
- ❌ Emergency room visits: $3,000-$10,000 per person
- ❌ Hospitalization: $15,000-$50,000+
- ❌ Emergency furnace replacement: $6,000-$9,000
- ❌ Lost work time: $500-$5,000
- ❌ Permanent neurological damage: Life-altering
- ❌ Death: Everything
Additional benefits:
- ✅ 15-20% more efficient operation (lower gas bills: $100-$300/year)
- ✅ Fewer repairs (catch small issues early)
- ✅ Longer equipment life (5-10 years extended)
- ✅ Better heating performance
- ✅ Maintained warranty compliance
Return on investment:
- Energy savings alone can exceed tune-up cost
- One prevented emergency repair pays for 3-5 years of maintenance
- You can’t put a price on your family’s safety
Carbon Monoxide Detectors: Your Last Line of Defense
Why You MUST Have CO Detectors
CO detectors save lives.
They’re required by California law (since 2011) in all homes with:
- Fuel-burning appliances (gas furnace, water heater, stove)
- Attached garages
- Fireplaces
But beyond legal requirements—they’re essential:
- Only way to detect odorless CO
- Alert you before lethal levels
- Wake you during sleep
- Give you time to evacuate
Proper CO Detector Installation
Where to install:
Required locations (California law):
- One outside each bedroom area
- One on every floor including basement/attic
Best practice:
- One in each bedroom (especially children’s rooms)
- One near furnace
- One in main living area
- One in basement
Installation height:
- Wall-mounted: 5 feet from floor (breathing height)
- Or ceiling-mounted (CO rises with warm air)
- Follow manufacturer guidelines
Where NOT to install:
- ❌ Inside closets or cabinets
- ❌ Within 15 feet of fuel-burning appliances (false alarms)
- ❌ In high humidity areas (bathrooms)
- ❌ Near fans or vents (air movement affects reading)
Choosing the Right CO Detector
Types:
1. Battery-operated
- Pros: Works during power outages, easy to install
- Cons: Batteries die, need replacement
- Cost: $20-$40
2. Hardwired with battery backup
- Pros: Always powered, battery backup for outages
- Cons: Requires electrical work, higher cost
- Cost: $50-$100 + installation
3. Plug-in with battery backup
- Pros: No electrical work, battery backup
- Cons: Uses outlet, can be unplugged
- Cost: $30-$60
Features to look for:
- Digital display (shows CO levels, not just alarm)
- Peak level memory (records highest reading)
- End-of-life warning (detector expires)
- Interconnected (all alarms sound together)
- Combined smoke/CO detector (space-saving)
Brands we recommend:
- Kidde
- First Alert
- Nest Protect (smart detector)
Maintenance and Replacement
Monthly:
- Test detector (push test button)
- Verify alarm sounds
- Check digital display works
Every 6 months:
- Vacuum detector to remove dust
- Replace batteries (battery-operated models)
Every 5-7 years:
- Replace entire detector
- Sensors degrade over time
- Don’t rely on old detectors
Check expiration date:
- Printed on back or inside battery compartment
- When it expires, replace immediately
- Expired detector = no protection
If Your CO Detector Alarms
NEVER ignore a CO alarm.
Immediate actions:
1. Evacuate immediately
- Get everyone out (including pets)
- Don’t waste time investigating
- Fresh air immediately
- Don’t open windows (leave that to fire department)
2. Call 911 from outside
- Tell them CO detector is alarming
- Give your address
- Mention anyone with symptoms
3. Don’t re-enter
- Wait for fire department
- They have equipment to measure CO
- They’ll ventilate your home
- They’ll clear you to return
4. Seek medical attention if symptoms
- Headache, dizziness, nausea = CO poisoning
- Go to ER immediately
- Tell them about CO exposure
- Treatment: High-flow oxygen
5. Have furnace inspected before using
- Don’t turn furnace back on
- Call HVAC professional
- Find and fix source of CO
- Only use after cleared safe
False alarms: Sometimes detectors alarm for other reasons:
- End of life
- Detector malfunction
- Temporary exposure (car idling in attached garage)
But ALWAYS treat alarms as real emergencies. Better safe than dead.
Bay Area-Specific CO Risks
1. Older Homes (San Francisco, Oakland, Berkeley)
Risk factors:
- Furnaces 20-50+ years old
- Original installations, never upgraded
- No modern safety features
- Higher crack risk
What to do:
- Annual inspections absolutely critical
- Consider replacement if 20+ years
- Modern furnaces have better safety
- Investment in your safety
2. Coastal Corrosion (SF, Pacifica, Daly City)
Risk factors:
- Salt air accelerates metal corrosion
- Heat exchangers rust faster
- Venting systems deteriorate
- Earlier failure than expected
What to do:
- More frequent inspections (consider every 6 months)
- Vigilant for rust signs
- Replace earlier than inland homes
- Stainless steel components when possible
3. Infrequent Use (Mild Climates)
Risk factors:
- Furnace sits idle 8-9 months
- Components deteriorate when not used
- First use of season can reveal problems
- Cobwebs, dust, debris accumulate
What to do:
- Pre-season inspection essential
- Run furnace monthly even in summer
- Don’t wait for cold weather to test
- Call before you need it
4. Earthquake-Prone Area
Risk factors:
- Seismic activity can crack heat exchangers
- Vent pipes can separate
- Gas connections can loosen
- Alignments shift
What to do:
- Inspect after any significant earthquake
- Check for gas leaks (smell)
- Verify vent connections
- Professional inspection if concerned
5. Rental Properties
Risk factors:
- Some landlords skip maintenance
- Tenants unaware of furnace age
- No maintenance records
- Older, neglected equipment
California law protects you:
- Landlords must provide working CO detectors
- Must maintain heating equipment
- You have right to safe housing
- Report violations to local code enforcement
What to do:
- Ask landlord for maintenance records
- Request annual furnace inspection
- Buy your own CO detector (don’t rely on landlord’s)
- Know your rights
Your Carbon Monoxide Safety Action Plan
Immediate Actions (Today)
1. Check your CO detectors
- ☐ Do you have them? (Required by law)
- ☐ Are they in correct locations?
- ☐ Are batteries fresh?
- ☐ Are they expired? (Check date)
- ☐ Test them (push button)
2. Check furnace age
- ☐ Find model/serial number on furnace
- ☐ First 4 digits = month/year manufactured
- ☐ If 15+ years old: Schedule inspection NOW
- ☐ If 20+ years: Consider replacement
3. Schedule annual tune-up
- ☐ Call (510) 391-5597
- ☐ Or book online
- ☐ Don’t wait for heating season
- ☐ September-October is ideal (before you need it)
This Heating Season
Before first use:
- ☐ Professional inspection completed
- ☐ Heat exchanger checked for cracks
- ☐ CO test performed
- ☐ All safety systems verified
- ☐ Filter replaced
During heating season:
- ☐ Monthly filter checks
- ☐ Listen for unusual sounds (especially booming)
- ☐ Watch for symptoms (headaches at home)
- ☐ Test CO detectors monthly
- ☐ Keep area around furnace clear
Long-Term Safety
Annual maintenance:
- ☐ Schedule every September/October
- ☐ Complete safety inspection
- ☐ Heat exchanger camera inspection
- ☐ Combustion analysis
- ☐ CO testing
- ☐ Keep records
Every 5-7 years:
- ☐ Replace CO detectors
- ☐ Major furnace component inspection
- ☐ Consider efficiency upgrade
Every 15-20 years:
- ☐ Plan for furnace replacement
- ☐ Modern safety features
- ☐ Better efficiency
- ☐ Peace of mind
When to Replace vs. Repair
Replace Your Furnace If:
Safety reasons:
- ❌ Cracked heat exchanger (NEVER repair, always replace)
- ❌ 20+ years old with any issues
- ❌ Multiple CO-related problems
- ❌ Rusted/corroded cabinet
- ❌ Yellow flickering flames (should be blue)
Financial reasons:
- ❌ Repair costs exceed $1,500
- ❌ Multiple repairs needed
- ❌ Inefficient (wasting money on gas)
Modern safety features you’re missing:
- ❌ Electronic ignition (vs. standing pilot)
- ❌ Induced draft blower
- ❌ Multiple safety switches
- ❌ Sealed combustion
Replacement cost: $4,000-$9,000
Your life is worth more.
Repair Your Furnace If:
Good candidates for repair:
- ✅ Less than 12 years old
- ✅ Well maintained
- ✅ Heat exchanger intact
- ✅ Minor component failure
- ✅ Repair under $800
But always get heat exchanger inspection first.
Schedule Your Life-Saving Furnace Tune-Up
Don’t wait. Don’t risk it. Don’t become a statistic.
Every single carbon monoxide death from a furnace was preventable. Every hospitalization. Every close call.
Annual maintenance isn’t optional. It’s life insurance.
Bay Area Climate Control
Carrier Factory Authorized Dealer
Serving the Bay Area Since 2010
Phone: (510) 391-5597
Online: Schedule Furnace Safety Inspection
Comprehensive Safety Inspection Includes:
- Complete heat exchanger inspection (camera)
- Combustion analysis
- Carbon monoxide testing (flue and ambient)
- All safety controls tested
- Burner cleaning and adjustment
- Written safety report
- Peace of mind
Cost: $150-$250
Value: Your family’s lives
Special: Mention this article for $25 off safety inspection
Service Area:
Alameda • Contra Costa • San Francisco • San Mateo • Santa Clara Counties
Available appointments:
- September-November (best time, before heating season)
- Same-week service available
- Emergency inspections (24/7)
Final Thoughts: A Message from Our Technicians
We’ve seen too many close calls. We’ve inspected furnaces that were actively leaking carbon monoxide while families slept upstairs. We’ve found cracks that would have killed someone within weeks.
Every single one could have been prevented with regular maintenance.
The $200 you save by skipping maintenance isn’t worth risking your family’s lives. It’s just not.
We don’t say this to scare you into buying our services. We say it because we’ve seen the consequences. We’ve talked to families in emergency rooms. We’ve seen the regret in homeowners’ eyes when they realize how close they came.
Please, don’t become another statistic. Schedule your furnace tune-up today.
Your family is counting on you.
Call (510) 391-5597 now to schedule your furnace safety inspection.
Your life is worth the phone call.