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Their furnace was short cycling and the house wouldn’t hold a steady temperature, so the homeowner called worried about comfort and safety as the wet season settles in. Short, frequent heating runs and inconsistent warmth are a clear sign something was wrong inside the system.
Short cycling led us to a cracked heat exchanger
When we inspected the 14-year-old gas furnace in Marysville, the short cycling was the symptom of a much bigger issue. A visual and diagnostic check revealed a crack in the heat exchanger, which explained why the burner kept shutting down prematurely and why the home could not stay at the set temperature.
A cracked heat exchanger matters because it affects both performance and safety. Besides reducing the unit’s ability to heat consistently, it can allow combustion gases to mix with the air circulated through the house, which is a serious safety concern for homeowners across Snohomish and King County.
How we diagnosed and temporarily secured the 14-year-old gas furnace
Our Altitude Heating & Cooling technician performed a careful inspection and ran the necessary combustion and safety tests to confirm the crack. We documented the findings and explained how the age of the unit factored into the options available, since older heat exchangers are more likely to develop stress fractures over time.
Because of the safety implications, we put temporary safety measures in place to protect the household. That included taking the furnace out of service so it would not run in an unsafe condition and verifying that the home’s indoor air quality and carbon monoxide indicators were not showing immediate danger. We scheduled a follow-up appointment for a full assessment so the homeowner could consider repair versus replacement with clear information.
Expect a professional assessment to walk you through realistic options and what each choice means for reliability and safety. If repair is feasible, a licensed technician can replace the failed components and re-test systems; if replacement is the safer long-term path, we’ll outline the right-sized, reliable options and the steps for a smooth swap-out.
What comes next and how this affects your winter plans
For now the home is safe and the furnace will remain offline until a full plan is in place. The homeowner has time to decide between repairing the cracked heat exchanger or replacing the aging unit, and we’ll be back to perform the full assessment and next steps.
If you’re in Marysville or anywhere in Snohomish and King County and notice short cycling or loss of temperature control, call Altitude Heating & Cooling at (425) 201-1998 or visit altitudeheating.com to schedule an inspection. We’ll make sure your home stays safe and warm through the winter.
What else we saw on this job
- The homeowner noticed louder startups and a slight odor when the burner ran, and the noise had been getting worse over a few weeks.
- Rooms swung between warm and cool, and the furnace started more often each day.
- Inside the furnace we found soot and uneven, unstable flames, along with signs the unit was overheating and tripping its safety shutdowns.
- We photographed the cracked heat exchanger and documented the findings for the homeowner’s records.
- The furnace was locked out of service and tagged so no one would restart it before the follow-up visit.
Is short cycling an emergency?
Short cycling is not always an emergency, but it should never be ignored. A dirty filter or a thermostat problem can cause it, and those are simple fixes. On an older gas furnace, short cycling can also point to overheating or a cracked heat exchanger, which can let combustion gases into your home. If short cycling comes with a burning smell, soot, a yellow flame or a carbon monoxide alarm, turn the furnace off and call right away. If your carbon monoxide alarm sounds, get everyone outside and call 911 first.
In Lake Stevens, Marysville and across Snohomish County, Altitude Heating & Cooling answers after-hours calls at 425-201-1998. Learn more about furnace repair and emergency HVAC service.
