How Earthquakes Affect Your HVAC System: Bay Area Homeowner's Guide

Living in Earthquake Country: Your HVAC System Is at Risk

The San Francisco Bay Area sits on some of the most seismically active land in the United States. According to the USGS, there's a 72% probability of a magnitude 6.7 or greater earthquake striking the Bay Area before 2043. For homeowners, this means your HVAC system—one of the most expensive and essential components of your home—faces risks that most people never consider.

At Galaxy Heating & Air Conditioning, we've responded to numerous post-earthquake HVAC emergencies throughout the Bay Area. Here's what every homeowner should know about earthquakes and their heating and cooling systems.

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How Earthquakes Damage HVAC Systems

Seismic activity can affect your heating and cooling equipment in several ways, some obvious and others hidden:

1. Gas Line Damage (Most Dangerous)

The Risk: Gas furnaces and water heaters connect to your home's natural gas supply through rigid or flexible gas lines. Earthquake movement can:

• Rupture gas lines at connection points
• Crack or damage flexible gas connectors
• Stress fittings and valves to the point of leakage

Why It Matters: Gas leaks create immediate explosion and fire hazards. Even small leaks can lead to carbon monoxide buildup in your home.

What to Do: If you smell the distinctive "rotten egg" odor of natural gas after an earthquake:

1. Do NOT turn on any electrical switches or appliances
2. Do NOT use your phone inside the house
3. Evacuate immediately
4. Call PG&E's emergency line: 1-800-743-5000

2. Refrigerant Line Breaks (Heat Pumps & AC Units)

The Risk: Air conditioners and heat pumps use copper refrigerant lines that connect indoor and outdoor units. These lines contain pressurized refrigerant that can leak if:

• Lines are kinked or stressed by equipment movement
• Connections at the outdoor unit are damaged
• The outdoor unit shifts off its mounting pad

Warning Signs:

• Hissing sounds near indoor or outdoor units
• Ice forming on refrigerant lines
• System not cooling or heating effectively
• Higher than normal energy bills after an earthquake

Environmental Note: Refrigerant leaks are harmful to the environment and require professional repair. Modern refrigerants like R-410A must be handled by EPA-certified technicians.

3. Ductwork Separation

The Risk: Your home's duct system is a network of sheet metal or flexible tubes running through walls, floors, and attics. Earthquake movement can:

• Separate duct sections at joints
• Collapse flexible ductwork
• Damage duct connections to registers and grilles

Hidden Danger: Ductwork damage often goes unnoticed because ducts are hidden in walls and attics. Symptoms include:

• Uneven heating/cooling between rooms
• Increased dust in your home
• Higher energy bills
• Reduced airflow from vents

4. Outdoor Unit Displacement

The Risk: Central AC units and heat pump outdoor units weigh 100-300+ pounds and sit on concrete pads or brackets. During earthquakes:

• Units can shift or slide off pads
• Refrigerant lines can be stressed or ruptured
• Electrical connections can be damaged or disconnected
• Units can tilt, affecting compressor operation

Inspection Tip: After an earthquake, visually check your outdoor unit. It should be level and centered on its pad. Any tilting or displacement requires professional assessment before operation.

5. Heat Exchanger Cracks (Furnaces)

The Risk: Your gas furnace's heat exchanger separates combustion gases from the air circulating through your home. Seismic stress can:

• Create hairline cracks in heat exchangers
• Worsen existing micro-cracks
• Lead to carbon monoxide leaking into your home's air supply

Why This Is Serious: Carbon monoxide is colorless and odorless. A cracked heat exchanger can silently poison your family. Symptoms of CO exposure include headaches, dizziness, nausea, and confusion.

Prevention: Install carbon monoxide detectors on every floor of your home. After any significant earthquake, have your furnace professionally inspected before use.

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Post-Earthquake HVAC Safety Checklist

Follow this checklist after any earthquake you can feel:

Immediate Actions (First 10 Minutes)

1. Turn off your HVAC system at the thermostat
2. Check for gas odor (rotten egg smell)
3. If you smell gas: Evacuate immediately, don't use electrical switches, call PG&E from outside
4. Check your gas meter for visible damage or hissing sounds
5. Locate your gas shutoff valve (know where it is before you need it)

Visual Inspection (When Safe)

1. Outdoor AC/Heat Pump Unit:

   • Check if unit has shifted from its pad
   • Look for tilting or leaning
   • Inspect visible refrigerant lines for kinks or damage
   • Check electrical disconnect for damage

2. Furnace/Indoor Unit:

   • Inspect visible gas line connections
   • Look for any displaced or fallen components
   • Check for water around the unit (if you have a condensing furnace)
   • Listen for unusual sounds

3. Ductwork (Accessible Areas):

   • Check attic ductwork if safely accessible
   • Look for separated joints or collapsed sections
   • Inspect duct boots at registers

4. Thermostat:

   • Check if thermostat has fallen or been damaged
   • Verify display is functioning

Before Restarting Your System

• Complete all visual inspections
• Confirm no gas odor is present
• Verify outdoor unit is stable and level
• Consider professional inspection if earthquake was significant (magnitude 5.0+)

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Protecting Your HVAC System Before an Earthquake

Take these preventive measures to minimize earthquake damage:

Seismic Strapping for Outdoor Units

Have your HVAC contractor install seismic straps or brackets that secure outdoor units to their pads. This relatively inexpensive upgrade can prevent:

• Unit displacement
• Refrigerant line damage
• Electrical connection failures

Flexible Gas Connectors

If your furnace still has rigid gas connections, consider upgrading to code-approved flexible gas connectors. These allow some movement without rupturing. Note: Only licensed contractors should work on gas connections.

Professional Duct Sealing

Properly sealed ductwork is more resistant to separation during earthquakes. Mastic sealant at joints provides both energy efficiency and earthquake resilience.

Water Heater Strapping

While not technically HVAC, your water heater's gas line connects to the same system. California law requires water heaters to be strapped to wall studs to prevent falling during earthquakes.

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When to Call a Professional

Contact an HVAC professional for inspection if:

• You experienced an earthquake magnitude 5.0 or greater
• Your outdoor unit has shifted or tilted
• You notice any unusual sounds or smells from your system
• Heating or cooling performance has changed since the earthquake
• You see any visible damage to equipment or lines
• Your system won't start after an earthquake
• Carbon monoxide detectors have alarmed (evacuate first, then call)

What to Expect from a Post-Earthquake HVAC Inspection

A thorough inspection should include:

• Gas leak testing with electronic detection equipment
• Visual inspection of all accessible components
• Refrigerant pressure check (for AC/heat pump systems)
• Heat exchanger inspection (for furnaces)
• Combustion analysis to verify safe operation
• Ductwork inspection in accessible areas
• Verification of proper drainage

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Bay Area Earthquake Preparedness: HVAC Edition

Living in earthquake country requires ongoing preparedness. Here's your HVAC earthquake readiness list:

1. Know your shutoffs: Locate gas and electrical shutoffs for your HVAC system
2. Keep emergency contacts handy: HVAC contractor, PG&E (1-800-743-5000)
3. Install CO detectors: On every floor, test monthly
4. Schedule regular maintenance: Well-maintained systems are more resilient
5. Document your system: Keep photos and records of your equipment
6. Consider earthquake insurance: Standard homeowner's policies don't cover earthquake damage

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The Bottom Line

Earthquakes are a fact of life in the Bay Area. While we can't prevent them, we can prepare our homes—including our HVAC systems—to minimize damage and keep our families safe.

If you've recently experienced an earthquake and have concerns about your heating and cooling system, or if you'd like a professional assessment of your system's earthquake readiness, Galaxy Heating & Air Conditioning is here to help. Our licensed technicians serve homeowners throughout the Bay Area with honest, professional HVAC services.

Emergency HVAC service available 24/7: (925) 578-3293

Stay safe, Bay Area.