Unexpected breakdowns rarely book themselves on a convenient day. One minute your home is working as expected and then in the next moment, you’re juggling between technicians, trying to figure out what’s wrong, and how to save up on repairs. One good news regarding such complex, costly, repairs is that in some cases they may be covered by home warranties, an inexpensive policy that is supposed to ease your mind when high-ticket home breakdown occurs. In order to save money, it is detrimental to know what is covered, and how to get the best bang for your buck.

These are the top 5 costliest home repairs

1) Central A/C or Heat Pump: Compressor or Coil Failure

Complexity:5/5

Typical cost:$2,500–$7,500 for major component replacement (full system change‑outs often exceed $10,000 and may fall outside warranty scope).

When cooling fails, it’s often the sealed refrigerant circuit: the compressor (the “heart” that pressurizes refrigerant) or the evaporator coil. Proper repair isn’t just swapping part, it requires a great deal of expertise and knowledge to solve.

Techs recover refrigerant, braze copper with a nitrogen purge, pull a deep vacuum to ~500 microns, and meter in the exact charge of R‑410A or R‑32. Dialing performance requires tuning superheat and subcooling and, at times, replacing a sticky TXV (thermal expansion valve).

Why warranties help: Most plans list HVAC as a covered “system,” but caps, refrigerant limits, and code upgrades (think new line sets or mandated pad/clearances) can be out‑of‑pocket.

2) Gas Furnace: Cracked Heat Exchanger

Complexity:4/5

Typical cost:$2,000–$4,500 for the exchanger; a full furnace replacement often $3,500–$7,500.

A heat exchanger isolates combustion gases from the air you breathe. Cracks are a safety issue as carbon monoxide is the concern and hence, techs go beyond a quick peek. Expect combustion analysis (CO ppm), checks on the inducer and pressure switch, and verification of proper temperature rise and airflow (CFM) after reassembly. Sometimes it is necessary to replace the entire furnace, especially if the unit is older.

Warranty angle: Wear‑and‑tear failures are commonly covered, while code upgrades, venting modifications, or duct changes usually aren’t.

3) Plumbing Slab Leak: Locate and Reroute

Complexity:4/5

Typical cost:$1,500–$6,500, depending on access and the length of reroute.

A pinhole under the slab can masquerade as a mystery water bill or warm spot on the floor. Pros use acoustic and thermal leak detection, isolate the line, and decide whether to open the slab or reroute through walls/ceilings, often done  with a PEX manifold for future repairs. 

Warranty angle: Plans frequently cover leak repair itself; extensive access, concrete/demo, and surface restoration (flooring, finishes) may be limited or excluded

4) Water Heater Replacement (Tank or Tankless)

Complexity:3–4/5

Typical cost:Tank:$1,200–$2,500. Tankless:$2,500–$5,000+.

A standard tank swap seems simple until properly inspected. This is when things may become complex. A correct T&P valve discharge, expansion tank, dielectric unions, and proper seismic strapping, can be complicated AND expensive.

Gas models need correct draft or, for high‑efficiency units, condensate management with a neutralizer. And tankless even raises the bar: gas line upsizing to meet BTU demand, Category III/IV venting, and a thorough flow calibration so your morning shower doesn’t play hot‑cold roulette.

 Warranty angle: Like‑for‑like replacements are common; conversions from tank to tankless, capacity upsizing, or code‑driven re‑venting often land outside coverage.

5) Main Electrical Service Panel: Burned Bus Bars or Failing Main

Complexity:4/5

Typical cost:$1,500–$4,000 for a like‑for‑like panel change (service upgrades cost more).

Panels age, and heat takes a toll on bus bars and breakers. A legitimate replacement involves coordination with the utility, verifying bonding/grounding (including Ufer or ground rods), performing a load calculation per NEC, and installing required AFCI/GFCI protection. Every single component here needs to be carefully inspected. 

Warranty angle: Many plans cover internal panel failures; service mast/meter socket, permitting, or capacity upgrades typically aren’t included.

What Home Warranties Usually Do And Don’t Cover

• Generally covered: The core repair or replacement of a failed system component caused by normal wear and tear (HVAC, plumbing, electrical, water heater).
  

• Often not covered or capped:Code upgrades, permits, haul‑away, asbestos/lead remediation, cosmetic matching, extensive access (e.g., large slab demo), efficiency or capacity upgrades, or issues tied to lack of maintenance or preexisting conditions.
  

• Read the fine print: Many contracts set per‑claim and annual dollar limits and impose separate refrigerant caps.
  

How to Make Claims Smoother (and Approvals Faster)

• Keep maintenance records. Annual HVAC tune‑ups, water‑heater flushes, anode‑rod checks. Keep detailed proofs.

• Capture the symptoms. Note error codes, take a photo of the iced‑over A/C line, record short cycling.

• Ask for the cause of failure in writing. Phrases like “shorted scroll compressor,” “cracked secondary heat exchanger,” or “heat‑damaged bus bar” help align the diagnosis with your policy language.

• Know your contract. Look into it properly and even write it down to yourself in layman’s language.

• Keep old parts when practical. It’s a simple way to document that replacement actually occurred.
  

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• Superheat/Subcooling: Measurements used to fine‑tune refrigerant charge for efficiency and compressor safety.]

• TXV:Thermal Expansion Valve, meters refrigerant into the evaporator coil.

• Micron Vacuum: Depth of vacuum (target ~500 microns) to remove moisture/air from a sealed HVAC system before charging.
  

• Heat Exchanger: Furnace component that transfers heat while keeping combustion gases separate from indoor air.
  

• PEX Manifold: Central hub for flexible plumbing runs that simplifies reroutes and future service.
  

• Dielectric Union: Fitting that prevents corrosion where dissimilar metals meet.
  

• AFCI/GFCI: Modern protective breakers, Arc‑Fault and Ground‑Fault, often required by code.
  

• Ufer Ground: Concrete‑encased grounding electrode used to safely bond the electrical system to earth.

Bottom Line

For complex, costly failures, a home‑warranty plan can be the difference between an urgent repair and an urgent financial problem, if appropriately covered, and if all necessary steps are taken beforehand when choosing a policy and running home maintenance. 

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