Common Denver Furnace Problems
Older homes in areas like Capitol Hill or the Highlands often have furnaces pushing 15 to 20 years old. The dry air here leads to a lot of static electricity, which can affect electronic ignition systems and control boards. Dust buildup from our low humidity is also a frequent culprit.
High-altitude operation affects gas pressure and combustion efficiency. A technician will check the gas valve pressure and flame sensor, which often get dirty or fail. Another local issue is poor ventilation due to heavy, wet snow blocking intake or exhaust vents on the side of the house.
What You Can Check Before Calling
- Make sure the thermostat is set to 'Heat' and the temperature is set above the current room reading.
- Check the circuit breaker for the furnace and the outdoor AC unit (they are often on the same circuit).
- Inspect the front panel on the furnace itself; it must be securely closed for the safety switch to engage.
- Replace your furnace filter if it looks dirty; a clogged filter is a top cause of airflow shutdowns.
- Ensure all exhaust vents on the outside wall are clear of snow, leaves, or debris.
How a Technician Diagnoses Your Furnace
The HVAC technician we connect you with will start by asking about the symptoms. Is the furnace making noise but not blowing air? Is it short-cycling on and off? This points them toward specific components.
They will perform a systematic check of the sequence of operation. This includes verifying the thermostat signal, checking for a clean air filter, testing the draft inducer motor, checking the ignitor or pilot light, and measuring the gas valve operation. They use tools like a multimeter and manometer to test electrical components and gas pressure.
Many repairs, like replacing a faulty flame sensor, hot surface ignitor, or pressure switch, can be completed in a single visit, typically within one to two hours. More complex issues like a cracked heat exchanger require a full system evaluation and a longer repair time.
When Furnace Repair Cannot Wait
If you smell a strong odor of gas or rotten eggs near the furnace, leave the house immediately and call for help from outside. Do not operate any light switches.
A complete lack of heat during a forecasted deep freeze is also an urgent situation. Pipes in Denver's uninsulated crawl spaces or older basements can freeze and burst quickly when temperatures plummet.
Hearing loud banging, screeching, or rumbling from the furnace are signs of a mechanical failure that could lead to a complete breakdown. It's best to shut the system off and call for service.
Typical Repair Costs in the Area
Repair costs depend entirely on the failed part and the labor involved. For common component swaps like a flame sensor or ignitor, the total cost typically ranges from $150 to $400 in the Denver metro.
More involved repairs, such as replacing a control board or a draft inducer motor, typically range from $400 to $800. The technician will provide a clear estimate before any work begins. Always ask for the old parts to be shown to you after replacement.
Questions homeowners ask
Why does my furnace keep turning off after a few minutes?
This is called short-cycling. In Denver, a common cause is a dirty flame sensor, which the safety system shuts the gas off to. A clogged air filter or blocked exhaust vent from snow can also cause overheating and shutdown. The technician will clean or replace the sensor and check the entire airflow path.
My pilot light keeps going out. What's wrong?
Older furnaces with standing pilot lights are common in Denver's historic homes. The issue is often a faulty thermocouple, a safety device that senses the pilot flame. The high altitude can also affect the pilot flame's stability. The HVAC technician will test the thermocouple and adjust or clean the pilot assembly.
How long should a furnace last in this climate?
With proper maintenance, a typical Denver furnace lasts 15 to 20 years. The dry air is less corrosive than humid climates, but the system works hard during our long, cold winters and can be stressed by temperature swings that require heat in the morning and AC by afternoon.
What does a noisy furnace indicate?
A high-pitched squeal often points to a failing blower motor bearing. Loud banging or popping when the furnace starts is usually ductwork expanding and contracting, common in older homes with metal ducts. Rumbling could indicate a dirty burner or a problem with the heat exchanger. The technician will identify the sound source.
Can I just replace my furnace instead of repairing it?
If your furnace is over 15 years old and needs a major repair, a replacement is worth considering. Newer models are significantly more efficient, which saves money during Denver winters. The technician can advise if a repair is cost-effective or if replacement makes more sense for your home.