Published November 14, 2025 • Updated April 14, 2026 • 7 min read
- If you smell gas or rotten eggs — leave immediately, do not touch switches, call the gas utility from outside
- A CO detector alarm is an emergency: evacuate and call 911, do not re-enter until cleared
- The most common heating failures (wrong thermostat setting, tripped breaker, clogged filter) take less than 5 minutes to check
- Press the furnace reset button only once — repeated resets can create a dangerous gas buildup
- In a well-insulated Utah home at 20°F outdoors, you have 9–18 hours before temperatures reach 50°F
- Salmon HVAC provides 24/7 emergency service throughout northern Utah — call (801) 397-0030
Step 1 — Safety First: Gas and CO Risks
Before you check anything else, take 30 seconds to address the two conditions that require immediate evacuation rather than troubleshooting. First: do you smell rotten eggs or sulfur anywhere in your home, near the furnace, or near the gas meter? Natural gas is odorized with mercaptan specifically so you can detect leaks by smell. If you smell it, leave the home immediately. Do not turn lights on or off, do not use your phone inside, do not try to find the source. Close the front door behind you, move to a neighbor's home or across the street, and call Dominion Energy at 1-800-323-5517. Do not re-enter the home until the utility has inspected and cleared it.
Second: is your carbon monoxide detector alarming? CO is odorless and colorless — you cannot detect it without a detector. If a CO detector is sounding, evacuate everyone including pets immediately. Get fresh air. Call 911. Do not re-enter the home. CO poisoning can incapacitate quickly and is fatal at high concentrations. If you do not have a CO detector within 10 feet of every sleeping area in your northern Utah home, install one before winter. Furnace heat exchanger cracks — which become more common in aging equipment — are the primary source of residential CO events during heating season.
Step 2 — Check the Simple Causes First
If there are no gas leak or CO concerns, work through these checks in order before calling for service. A significant percentage of heating service calls — our technicians estimate 25–30% — turn out to have a cause the homeowner could have resolved without a service visit. Checking these first costs you 5–10 minutes and can save you an emergency call fee.
The Quick Checklist (5–10 minutes)
- Thermostat settings: Is it set to "Heat" mode? Is the setpoint above current room temperature? Is the fan set to "Auto" or "On" (not "Off")? Check batteries if it is a battery-powered thermostat — a dead thermostat looks exactly like a dead furnace.
- Circuit breaker: Go to your electrical panel and look for a tripped breaker (partially switched, between On and Off) labeled "Furnace," "Air Handler," or "HVAC." Reset it by pushing it fully to Off, then back to On. If it trips again immediately, stop — a breaker that trips immediately indicates an electrical fault that requires a technician.
- Furnace power switch: There is a wall switch near the furnace that looks like a standard light switch. Make sure it is in the On position. It is easy to knock off accidentally or flip when reaching past it in a utility room.
- Air filter: A severely clogged filter can cause the furnace to overheat and trip its high-limit safety control, shutting the system off. Pull the filter and inspect it. If it is visibly loaded — gray or brown with debris — replace it and try restarting the furnace.
- Furnace reset button: If none of the above resolves the issue, locate the furnace's reset button (typically red or yellow, on the burner assembly). Press it once. Wait 30–60 seconds for the furnace to attempt a restart. Listen for the igniter clicking and the burner lighting. If the furnace fires and runs, monitor it for 15 minutes to confirm it holds. If it locks out again — or if you hear clicking but no ignition — call a technician.
Step 3 — Identify Whether It's a Furnace or System-Wide Issue
If your quick checks did not resolve the problem, the next question is whether the issue is isolated to the furnace or involves the broader system. Try turning the thermostat fan setting to "On" (continuous fan, not heating). If the blower runs but no warm air comes out, the problem is in the heating side — burner, igniter, gas valve, or heat exchanger. If the blower does not run at all, the problem may be in the air handler or electrical supply.
Check your furnace's diagnostic LED if it has one — most furnaces installed after 2005 have a small LED light that flashes a code when a fault is detected. The code key is usually printed on the inside of the furnace door. Common codes include: pressure switch fault (often caused by a blocked flue or condensate drain), ignition lockout (igniter or gas valve issue), limit switch trip (often caused by restricted airflow — check filter), and flame sensor fault (the flame sensor needs cleaning). Knowing the code when you call for service helps the technician arrive prepared with the right parts and can reduce the time to repair.
Step 4 — Staying Warm Safely While You Wait
If you have determined you need a technician and the indoor temperature is dropping, take steps to conserve heat and keep your household comfortable until the repair is complete. Close interior doors to consolidate people and heat into fewer rooms — a bedroom with three people in it warms up and stays warmer than a large open living area. Add layers. If you have a fireplace that is functional and properly maintained, use it — but ensure the flue is open and the fireplace has been inspected recently.
Electric space heaters are acceptable temporary heating sources with important precautions: use only UL-listed units with automatic tip-over shutoff, keep them away from anything flammable, plug directly into a wall outlet (not an extension cord), and never leave them unattended or run them while sleeping. A 1,500-watt space heater can heat a single bedroom-sized space adequately. Do not use gas camping stoves, propane heaters designed for outdoor use, charcoal grills, or kitchen ovens for indoor heating — all of these produce carbon monoxide in enclosed spaces and have caused deaths in exactly the scenario of a winter heating outage.
Step 5 — What to Have Ready When You Call
When you call Salmon HVAC or any emergency HVAC service, having specific information ready helps the dispatcher route the right technician and helps that technician arrive prepared. The most useful information is your furnace make and model number — found on the data plate inside the front panel, usually near the burner or blower compartment. Write this down or photograph it now, before you need it.
Also useful: the approximate age of the equipment, the current indoor temperature, a description of what the furnace is doing (nothing at all, attempting to start and then shutting off, producing a clicking sound without igniting, making unusual sounds), whether any diagnostic LED codes are showing, and what you tried in your initial checks. If you have a service history for the equipment — when it was last serviced, any recent repairs — that context can help diagnose faster. Salmon HVAC serves Centerville, Bountiful, Layton, Farmington, Kaysville, Ogden, and all of Davis and Weber County. Our emergency line is staffed 24/7.
When to Call for Emergency Service vs. Wait Until Morning
Not every heating failure is a same-night emergency. The decision to call for after-hours emergency service — which carries a higher service fee — versus waiting for regular business hours depends on a few factors. Call for emergency service if: indoor temperatures are dropping and you have young children, elderly residents, or anyone with a medical condition that makes cold exposure dangerous; outdoor temperatures are forecast below 10°F, creating pipe freeze risk; or the system failure is accompanied by a gas smell, CO alarm, or the smell of burning or smoke.
You can reasonably wait for morning service if: the system failure occurred on a mild night (above 30°F outdoor temperature), the home is well-insulated and indoor temperature is still above 60°F, you have adequate temporary heat sources to get through the night safely, and no vulnerable occupants are present. A well-insulated northern Utah home at 20°F outdoors will reach 50°F in 9–18 hours — enough buffer to wait for a morning appointment in most cases. When in doubt, call — Salmon HVAC can help you assess the situation by phone and determine urgency before dispatching a technician.
Heating Emergency? We're Available 24/7
Salmon HVAC provides emergency heating service throughout northern Utah. If your furnace stops working and you need help now, call us. No overtime charges on weekdays during regular hours, and fair emergency rates for after-hours calls.
Frequently Asked Questions
What are the signs of a gas leak when my furnace stops working?
Natural gas is odorized with mercaptan, which smells like rotten eggs or sulfur. If you smell this near your furnace or anywhere in your home, leave immediately without touching switches, close the front door behind you, and call Dominion Energy (1-800-323-5517) from outside. Do not re-enter until the utility has inspected and cleared the structure.
How do I reset my furnace when it stops working?
Most modern furnaces have a reset button on the burner assembly — typically red or yellow. Press it once and wait 30–60 seconds for the furnace to attempt a restart. If the furnace locks out again, do not press the reset button a second time. Repeated resets can force unburned gas into the heat exchanger, creating a hazard. One reset attempt is appropriate; a second lockout means call a technician.
Is it safe to use a space heater while waiting for furnace repair in Utah?
Yes, with precautions. Use only UL-listed electric space heaters with automatic tip-over shutoff. Keep them away from bedding, curtains, and furniture. Never run them unattended or while sleeping. Plug directly into a wall outlet — no extension cords. Never use gas camping stoves, outdoor propane heaters, or ovens for indoor heating; all produce carbon monoxide in enclosed spaces.
What information should I have ready when calling for emergency HVAC service?
Have the following ready: furnace make and model number (on the data plate inside the front panel), approximate equipment age, current indoor temperature, a description of what the furnace is or isn't doing, any diagnostic LED codes showing on the furnace, and a summary of what you already checked. This helps the technician arrive with the right parts and diagnose faster.
How quickly will my Utah home lose heat without a furnace in winter?
In a well-insulated northern Utah home at 20°F outdoors, indoor temperature typically drops 1–2°F per hour. A home starting at 68°F will reach 50°F in 9–18 hours. During extreme cold events at -5°F to -10°F — common on Davis and Weber County benchlands — heat loss is faster. Pipe freeze risk increases when temperatures in exterior walls drop below 32°F, typically 15–20 hours into a heating outage on a very cold night.
