In Northern Utah, the furnace is the one appliance nobody wants to think about until it stops. Winter nights here can drop below zero, and freeze-thaw swings keep a heating system busy from October into April. This guide explains how a gas furnace works, what the early warning signs sound like, and how to decide between a repair and a new system.
What happens when your furnace turns on?
When the thermostat calls for heat, a gas furnace runs through the same steps every time. Knowing them helps you describe a problem and understand what a technician finds.
- The inducer fan starts first and pulls air through the burner area to clear it.
- A safety switch confirms that air is moving before gas is allowed in.
- The igniter glows hot, the gas valve opens and the burners light.
- The flame sensor proves there is a flame. If it cannot, the gas shuts off.
- The heat exchanger warms up and keeps the burner gases separate from the air in your home.
- The blower pushes house air across the hot heat exchanger and out through your vents.
If any one step fails, the furnace stops and tries again. Many control boards flash a light code that tells a technician which step failed.
Warning signs your furnace needs attention
Furnaces usually give some hint before they quit. Pay attention to these in the fall, when you first switch from cooling to heating.
It starts, then shuts off within a minute
This is one of the most common calls we get. A dirty flame sensor is often the cause. A blocked vent or a clogged filter can also make the furnace shut itself down for safety.
The air from the vents is lukewarm
The blower runs, but the burners are not lighting or not staying lit. It could be the igniter, the gas supply, or a pressure switch that never closes.
Rooms heat unevenly
One bedroom stays cold while the living room is too warm. That points to airflow trouble, such as closed vents, leaky ducts or a blower that is struggling.
Loud bangs, rattles or squeals
A small whoosh when the burners light is normal. A loud bang can mean delayed ignition. A squeal often means a worn blower motor or belt.
Your heating bill jumps
If the weather is about the same as last year but the gas bill is much higher, the furnace may be running longer to do the same job. That is often a sign of wear or a maintenance problem.
If you smell gas, leave the house first and call your gas utility from outside. Do not flip switches on the way out. Once the utility says it is safe, call us for the furnace.
Repair or replace your furnace?
A furnace repair is often the sensible move, but not always. Here is how we help homeowners think it through.
Look at the part, not just the price
Igniters, flame sensors, pressure switches and capacitors are routine repairs on any furnace. A cracked heat exchanger is serious. On an older furnace, that finding usually means replacement, because the heat exchanger keeps burner gases out of your living space.
Count the repairs
One repair after years of quiet service is normal. When the furnace needs a new part every winter, the money may be better spent on a new system.
Think about comfort, too
Older single-speed furnaces blast on and off. Newer two-stage and variable-speed models run longer at a lower, steadier output. That gives you more even temperatures and quieter operation.
Our furnace repair visits start with a full diagnosis. We explain what failed, what it will cost, and whether the furnace is worth fixing before any work begins. If replacement is the better path, see our furnace replacement page.
Choosing a new furnace
We install Goodman and Amana furnaces and offer free estimates on new system installations. A new furnace is a long-term purchase, so a few details matter more than the brand name on the cabinet.
Size it to the house
A furnace that is too big heats fast and shuts off, which wears parts and leaves cold spots. Too small, and it runs nonstop on the coldest nights. We size based on your home, not on the label of the old unit.
Check the efficiency rating
Furnaces carry an AFUE rating, which tells you how much of the gas you buy turns into heat for your home. High-efficiency models vent through plastic pipe and need a drain for the water they make. We will tell you if your home is set up for one.
Match it to your AC
The furnace blower moves air for your air conditioner too. Pairing them correctly keeps both running well.
Our furnace installation page explains the full process. Financing is available through our lending partners on our financing page.
Get your furnace ready for winter
The first cold snap of the year is the busiest time for furnace calls. A little work in September or early October can keep you out of that rush.
- Change the filter. Start the season with a clean one and check it monthly.
- Test the heat early. Turn the thermostat up on a cool afternoon. A dusty smell for a few minutes is normal. A smell that lingers is not.
- Clear the vents. Make sure furniture and rugs are not covering supply or return grilles.
- Check the outside vents. High-efficiency furnaces vent out the side of the house. Keep snow and leaves away from those pipes all winter.
- Test your CO alarms. Replace batteries and make sure there is an alarm near the bedrooms.
A professional tune-up goes further. Our furnace maintenance visit cleans the burners and flame sensor, checks the heat exchanger, tests the safety switches, and includes combustion analysis and carbon monoxide testing. Members of our VIP Maintenance Plan get a yearly 88-point HVAC and plumbing inspection with priority scheduling.
Small habits that help your furnace all winter
A furnace that is treated well tends to break down less and cost less to run. None of these steps need tools.
Pick a steady setting
Big swings make the furnace work hard to catch up. A modest setback at night or while you are at work is fine. A programmable or smart thermostat can handle the changes for you.
Keep the return air open
Return grilles pull air back to the furnace. When a couch or a rug covers one, the furnace has to fight for air. That can overheat the heat exchanger and trip a safety switch.
Watch the snow line
After a big storm, walk around the house and look at the furnace intake and exhaust pipes. A drift can block them in one night and shut the furnace down.
Listen once in a while
You know how your furnace usually sounds. If a new rattle, hum or squeal shows up, call before it turns into a no-heat night.
When the heat goes out at night
Furnaces do not wait for business hours. Before you call, check three things: the thermostat has fresh batteries and is set to heat, the furnace switch is on, and the breaker has not tripped. If none of those helps, we offer 24/7 emergency service for no-heat calls.
Call us about your furnace
Questions about a noise, a smell or an old furnace? Call (435) 730-2536. Our office is open Monday to Friday, 8 AM to 6 PM, with 24/7 emergency service on the same line, or you can schedule online.
Common questions
Why does my furnace smell like dust when I first turn it on?
Dust settles on the heat exchanger over the summer and burns off the first few times the furnace runs. If the smell lasts more than an hour or smells like burning plastic, turn the furnace off and call us.
How often should I change my furnace filter?
Check it every month during the heating season. Most standard filters need changing every one to three months, more often with pets or during dusty stretches.
Is it safe to run my furnace if it keeps shutting off?
A furnace that shuts off is protecting itself. Resetting it once is fine, but if it keeps happening, stop and have it checked, since the cause may be a blocked vent.
What does a cracked heat exchanger mean?
The heat exchanger keeps burner gases out of your home's air. A crack means the furnace should not be used until it is repaired or replaced.