Furnace not heating your home in Calgary

If your furnace is running but your home still feels cold, you are not alone. In Calgary, a small issue can feel big fast when the temperature drops. This guide walks you through simple checks you can do at home, what the common warning signs mean, and when it is time to call for service.

Quick safety check before you start

Start with safety. If you smell gas, leave the home and contact your gas provider or emergency services. If anyone feels dizzy, has a headache, or you suspect carbon monoxide, leave the home right away and get help. If you are ever unsure, stop and call a professional.

Step one check the thermostat

This sounds basic, but it is the most common cause of “no heat” calls.

Make sure it is set to heat

• Set the mode to Heat.
• Set the temperature a few degrees above the current room temperature.
• If your thermostat has a schedule, switch to a temporary hold and test again.

Check the fan setting

If the fan is set to On, it will run all the time. That can make the air feel cool even when the furnace is fine. Set it to Auto so the fan runs only during heating cycles.

Replace the batteries if needed

Many thermostats use batteries. Low batteries can cause strange behavior, blank screens, or failed calls for heat. Replace them, then test again.

Step two check power to the furnace

A furnace needs power to run its control board, blower motor, and safety system.

Look for the furnace switch

Many homes have a light switch near the furnace that turns it on and off. Make sure it is switched on. It is easy to bump by accident.

Check the breaker

Look at your electrical panel for a tripped breaker labeled Furnace or HVAC. If it is tripped, reset it once. If it trips again, stop and call a technician.

Make sure the furnace door is fully closed

Most furnaces have a safety switch that prevents operation if the access panel is not seated correctly. If you changed a filter recently, the door may not be latched. Open and re-seat the panel, then try again.

Step three check the air filter

A clogged filter can reduce airflow so much that the furnace shuts down to protect itself. It can also cause rooms to heat slowly and unevenly.

Signs your filter is the problem

• Your furnace starts, then stops after a short time.
• Some rooms are much colder than others.
• You notice weak airflow from vents.
• The filter looks gray, dusty, or packed with debris.

What to do

• Turn the furnace off before removing the filter.
• Replace it with the same size.
• Use a filter type your system can handle. Very dense filters can restrict airflow on some systems.
• Turn the furnace back on and test heat again.

Step four check vents and return air

Your furnace can only heat your home well if air can move through the system.

Make sure supply vents are open

Walk room to room and check that vents are open and not blocked by rugs, furniture, or drapes.

Do not block return vents

Return vents pull air back to the furnace. If returns are blocked, the system can struggle, overheat, and shut down. Make sure they are clear.

Check for closed doors

In many homes, keeping doors closed can reduce airflow and pressure balance. If one room is always cold, try leaving the door open for a few hours and see if it improves.

Step five listen and look for clues

Your furnace often tells you what is wrong. You just need to know what to look for.

Look for an LED status light

Many furnaces have a small viewing window that shows a blinking light. The pattern can point to a specific issue. The code list is often on the inside of the furnace door panel. If you see a repeating pattern, note it before you turn anything off.

Common sounds and what they can mean

• Clicking but no heat can point to ignition issues.
• Rattling can mean a loose panel, duct, or blower component.
• Whistling can mean restricted airflow from a dirty filter or closed vents.
• Banging can be duct expansion, or a more serious mechanical issue.

Short cycling

If your furnace starts and stops often, it may be overheating, getting poor airflow, or dealing with a sensor problem. Short cycling wastes energy and can wear parts faster.

Common Calgary winter issues

Cold snaps, wind, and snow can create problems that do not show up in mild weather.

Snow or ice blocking intake or exhaust pipes

High efficiency furnaces often vent through pipes outside. If snow drifts or ice blocks those pipes, the furnace may shut down for safety. If you can safely reach the area, clear snow away from the vents. Do not chip at pipes with sharp tools.

Frozen condensate drain line

High efficiency furnaces produce condensation. If a drain line freezes, the furnace can stop. If you see water around the furnace, turn it off and call a technician. Water can damage parts and flooring.

Strong winds and pressure changes

High winds can affect venting on some systems. If heat fails during very windy weather and returns later, note the timing. A technician can check venting and pressure settings.

When the furnace runs but the air feels cold

Sometimes the blower is moving air, but the burners are not heating it.

Igniter or pilot system issues

Modern furnaces use an igniter to light the burners. If the igniter fails, the furnace may try a few times, then lock out. This is not a DIY part swap for most homeowners, but noting the behavior helps the technician.

Flame sensor problems

A dirty flame sensor can stop the furnace from staying lit. The unit may light briefly, then shut off. A technician can clean or replace it safely.

Overheating from restricted airflow

If airflow is poor, the furnace can overheat and shut down. A clogged filter, blocked vents, or duct issues can trigger this. This is why checking airflow and filters is so useful.

When you should call a technician

Call for service if any of these are true.

• You smell gas or suspect a safety issue.
• The breaker trips again after one reset.
• The furnace shows an error code you cannot clear.
• You replaced the filter and checked vents, but you still have no heat.
• You see water around the furnace.
• The furnace keeps short cycling.
• Some rooms never warm up, even after hours.

FAQ Furnace not heating in Calgary

Why is my furnace blowing air but not heating

This often happens when the blower runs but the burners do not stay lit. Common causes include ignition problems, flame sensing issues, or a safety lockout. A dirty filter can also trigger overheating and shut the heat off.

How long should a furnace run in Calgary winter

Run time changes with outdoor temperature, home size, insulation, and thermostat settings. Long run times during cold snaps can be normal. Short cycles that start and stop every few minutes are not normal and should be checked.

Should I keep the fan on or auto

Auto is best for most homes. Fan on can help mix air, but it can make the air feel cooler between heating cycles and may move more dust if filters are dirty.

How often should I change my furnace filter

Many homes do well with a change every one to three months. Homes with pets, renovations, or allergies may need more frequent changes. If airflow feels weak, check the filter sooner.

Is it safe to reset my furnace

Basic resets like checking the thermostat, turning the furnace switch off and on, and replacing the filter are usually fine. If you see repeated lockouts, tripped breakers, or error codes, stop and call a pro.

Simple prevention for the next cold snap

A little routine care can prevent a lot of stress.

• Replace filters on a schedule.
• Keep supply and return vents clear.
• After heavy snow, check that outdoor vents are not blocked.
• Book a seasonal maintenance visit before deep winter arrives.
• Pay attention to new sounds or odors and address them early.

Your next step

If you tried the checks above and your home still is not warming up, it is time for a professional diagnosis. A technician can test ignition, sensors, airflow, and venting safely, then explain the fix before work starts.