Most homeowners think power surges are dramatic events.
Lightning strikes.
Big storms.
Neighborhood-wide outages.
But the surges that quietly kill electric furnaces?
Those happen every day, often inside your own home.
Goodman 68,240 BTU 20 kW Electric Furnace with 2,000 CFM Airflow - MBVK20DP1X00, HKTAD201
I’ve replaced more control boards and fried components from small, repeated surges than from major storms. And the frustrating part is this:
👉 Almost all of that damage is preventable.
This guide explains:
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What power surges really are
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How they damage electric furnaces (especially Goodman systems)
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Why the damage often shows up months later
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What surge protection actually works
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How surge protection pays for itself
No scare tactics. Just the truth from the field.
🧠 What a Power Surge Really Is (Not Just Lightning)
A power surge is a sudden spike in voltage above what your equipment is designed to handle.
Your electric furnace expects steady, predictable power. Surges throw that off balance.
Common surge sources (most homeowners miss these)
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Utility grid switching
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Power outages and restorations
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Large appliances cycling on/off
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HVAC motors starting
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Solar system interactions
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Generator transfers
Lightning gets the blame—but most surges come from inside the house.
Power surge basics:
👉 U.S. Department of Energy – Power Surges
https://www.energy.gov/energysaver/articles/save-energy-your-household-smart-power-strip
⚡ Why Electric Furnaces Are Especially Vulnerable
Electric furnaces are more sensitive than gas systems.
Here’s why:
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They rely entirely on electricity
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They use high-amperage components
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They contain delicate control boards
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They often integrate with smart thermostats
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They switch large electrical loads frequently
Every surge stresses those components—even if nothing fails immediately.
🔥 The Furnace Parts Surges Damage First
Surge damage rarely takes out the whole system at once. It weakens parts over time.
🎛️ Control Boards (The #1 Casualty)
Control boards manage:
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Heat strip staging
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Blower operation
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Safety limits
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Thermostat communication
Surges cause:
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Micro-arcing on circuits
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Component overheating
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Corrupted logic
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Random failures months later
This is why furnaces start acting “possessed.”
⚡ Relays, Contactors & Transformers
These parts handle switching power on and off.
Surge damage leads to:
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Pitted contacts
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Sticking relays
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Buzzing or clicking sounds
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Inconsistent operation
They don’t always fail cleanly—they fail intermittently, which is worse.
🔥 Heat Strip Terminals & Wiring
Surges can:
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Overheat terminals
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Loosen connections
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Cause discoloration
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Increase resistance
That extra resistance creates heat, which creates more damage.
📱 Smart Thermostats & Low-Voltage Circuits
Smart thermostats are surge magnets.
Why?
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Constant connection to control boards
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Low-voltage sensitivity
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Network connectivity
One surge can:
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Kill a thermostat outright
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Damage furnace controls through the wiring
Smart thermostat protection matters more than people think.
🕰️ Why Surge Damage Often Shows Up Later
This is the tricky part.
Surge damage is often cumulative.
What happens
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A surge weakens a component
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The system keeps running
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Heat and load finish the job over time
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Failure shows up weeks or months later
That’s why homeowners say:
“It worked fine until recently.”
It didn’t. It was injured and limping.
🔍 Warning Signs of Surge-Related Furnace Damage
Watch for these patterns:
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Random shutdowns
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Blower runs but no heat
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Heat strips won’t stage properly
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Breakers trip unexpectedly
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Control boards replaced more than once
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Smart thermostat resets or drops connection
These are classic surge aftermath symptoms.
🛡️ Surge Protection Options (What Actually Works)
Not all surge protection is equal.
🏠 Whole-Home Surge Protection (Best First Line)
Installed at the main electrical panel, this:
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Protects all circuits
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Handles large external surges
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Reduces cumulative damage
This is your foundation layer.
Whole-home protection overview:
👉 Electrical Safety Foundation International (ESFI)
https://www.esfi.org/home-electrical-safety/
🔧 Dedicated HVAC Surge Protectors (Highly Recommended)
These are installed directly on the furnace circuit.
They:
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Protect sensitive HVAC electronics
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Absorb spikes before they reach control boards
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Work alongside whole-home protection
For electric furnaces, this is where real savings happen.
🔌 Plug-In Protectors (Limited Use)
Plug-in protectors:
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Do not protect hardwired furnaces
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Offer minimal protection for thermostats only
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Should never be your only solution
They’re supplemental—not primary.
💰 Why Surge Protection Pays Back (Real Numbers)
Let’s talk cost.
Typical repair costs
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Control board replacement: $300–$900+
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Transformer replacement: $150–$400
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Diagnostic visits: $100–$200 each
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Smart thermostat replacement: $200–$400
Surge protection costs
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Whole-home surge protector: $200–$500 installed
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HVAC surge protector: $100–$300 installed
One avoided repair often pays for all of it.
🧰 When Surge Protection Is a Must (Not Optional)
I strongly recommend protection if you have:
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An electric furnace
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A smart thermostat
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Frequent power outages
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Rural or older utility lines
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Solar panels or generators
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Expensive control boards
If your furnace has a circuit board, it deserves protection.
⚙️ Maintenance Tips to Keep Surge Protection Working
Surge protectors don’t last forever.
Best practices
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Check indicator lights annually
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Replace units after major lightning events
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Inspect during electrical upgrades
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Don’t ignore “failed” indicators
A dead surge protector protects nothing.
❌ Common Surge Myths That Cost Homeowners Money
“My breaker will protect the furnace.”
→ Breakers protect wiring, not electronics.
“Lightning never hits here.”
→ Most damage comes from switching, not lightning.
“Surge protection is overkill.”
→ Not for modern electric furnaces.
📋 Power Surge Protection Checklist
✔ Whole-home surge protector installed
✔ HVAC-dedicated surge protector added
✔ Smart thermostat protected
✔ Indicator lights checked yearly
✔ Protection replaced when failed
🧠 Final Word from Mike
Power surges don’t announce themselves.
They don’t always trip breakers.
They don’t always cause immediate failure.
They quietly shorten the life of your furnace—one spike at a time.
Surge protection isn’t flashy, but it’s one of the highest ROI upgrades you can make for an electric furnace.
Protect the brain of the system, and the rest lasts longer.
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In the next topic we will know more about: Cut Dust, Cut Costs: Ductwork Cleaning & Furnace Longevity
