Furnace Guide Introduction

As Albertans, it’s important for us to have close, warm relationships with our furnaces. Sure, you like to avoid using it as much as possible, but when the temperature starts to drop, you have to be able to rely on your furnace to keep you and your family safe and comfortable.

It’s important to understand how your furnace works, and know how to properly maintain and take care of your furnace and central heating system. The last thing you want to worry about is waking up in the middle of a cold winter night to a broken furnace and a freezing home. With this handy guide, you can expand your furnace knowledge, avoid mishaps, and extend the overall life of your furnace.

At Canuck Plumbing and Heating, we have over 15 years of experience serving customers in Edmonton, Fort Saskatchewan, and the surrounding area with friendly and reliable HVAC and plumbing installation, maintenance, and furnace repair services. We know everything there is to know about furnaces and we’d love to pass that knowledge on to you. We’re not just blowing hot air!

Table of Contents

What Exactly is a Furnace?

In the simplest possible terms, a furnace is a device used for heating things to high temperatures. Most likely, there’s a furnace somewhere in your home, hidden in an out of the way location like a closet or basement. It’s a large metal appliance that converts fuel or electricity to heat. Your household furnace keeps your home warm by heating air and then circulating it throughout your entire central heating system.

A central heating system is any heating system that generates heat in one central location and then distributes it throughout an entire building using ductwork, vents, and registers. Ducts are generally made of galvanized metal pipes that begin at the furnace and stretch all throughout your home, leading to vents and heat registers.

You’ll find registers throughout your home in floors, walls, and ceilings. The warm air from the furnace is blown out of the registers. Vents or vent grills can also be found on walls and ceilings and can be used to distribute warm air; however, most often, vents are used as intakes that extract air from a room and then cycle it back through your central heating system.

Your furnace and central heating system are the most important part of your larger overall heating, ventilation, and air conditioning (HVAC) system. 

Chapter 1: How Does My Furnace Work?

Before you can begin doing any maintenance or trying to fix any problems your furnace is having, it’s important to know exactly what your furnace does and how your central heating system works.

Furnace Components

The first step in understanding how your furnace works is recognizing the main components of your central heating system. Most systems are made up of the following parts:

  • Burners This is the part of your furnace where air and fuel are combined and burned to produce heat.
  • Fan and Blower Assembly – The fan and blower are a simple motor and fan that work to draw new air into the furnace, and blow warm air out.
  • Heat Exchanger – The heat exchanger is a set of coils or tubes that are looped together inside the furnace where the air is heated.
  • Flue – The flue is the angular pipe coming out of the top of the furnace that vents away dangerous gases away from the furnace and out of your home.
  • Ducts and Vents – Your ductwork is the galvanized metal pipes that run throughout the floors, walls, and ceilings of your home and delivers warm air from the furnace out of the vents and registers.

Fuel and oxygen are combined and ignited by your furnace’s burner system. This produces a strong, blue flame that heats the heat exchanger. Air is drawn into the furnace and heated in the heat exchanger, and then the fan and blower assembly blow the air through the ductwork, distributing warm air throughout your home. 

Furnace Safety

Generally, it’s quite safe to do routine cleaning and maintenance on your furnace and heating system. Although, improper maintenance or faulty repairs can lead to expensive damage to your furnace and heating system, or even dangerous gas leaks, fires, or explosions.

However, as long as you follow the manufacturer’s instructions and keep a few of our basic safety tips in mind, you’ll have no problem keeping your furnace running safely and efficiently:

  • Anytime you plan on doing any cleaning or maintenance, be sure to turn off both the gas and the power to the furnace.
  • Obviously, your furnace can get extremely hot, especially the burners and the heat exchanger, but even the front grill too. If you’re going to clean or inspect your furnace, ensure that it hasn’t been recently running and it’s sufficiently cooled down.
  • Teach children and pets not to play near the furnace.
  • Keep the area around your furnace clean, ventilated, and unobstructed.
  • Never store any highly combustible materials like gasoline, oils, paint thinners, etc. anywhere near your furnace.
  • Don’t close more than 20% of the registers in your house. This can cause a high resistance in your heating system and result in excessive heat building up in your furnace, possibly causing expensive or irreparable damage.

For more information on how to be as safe as possible around your furnace click here

Additional Links:

What is a Furnace Burner?

Chapter 2: The Right Furnace for You

These days, the vast majority of homes in Alberta are fitted with forced-air natural gas furnaces. Not only are they the most economical choice, but they’re also the best equipped to handle our harsh winters. However, some homes still use oil-fired furnaces, especially older homes like those found in Edmonton’s historic neighbourhoods

And of course, with growing interest in energy efficiency and alternative fuel sources, electric furnaces and solar heaters are also growing in popularity.

Buying a furnace is a major investment and it requires some research, so make sure you do your homework and choose the furnace that’s best suited to your needs.

You’ll also notice that many furnace products offer a BTU (British Thermal Unit) rating, which is a measurement of how much fuel it takes to heat one cubic square foot of your home.

While you can’t get a furnace to put out more or less energy, a BTU rating can tell you (for comparison purposes) how much fuel you will use to attain a specific level of heat.

Furnace Brands You Can Trust

There are many different manufacturers of furnaces, and while many of them will get the job done, some brands offer more value in efficiency, reliability, better warranties, easier installation, etc.

At Canuck Plumbing and Heating, we recommend and carry Comfortmaker brand furnaces. Our experienced and certified HVAC professionals believe that Comfortmaker offers an outstanding value in the areas of quality, energy efficiency, and reliability. Comfortmaker offers industry-leading “No Hassle Replacement” warranties on many of their top of the line products. Comfortmaker is a subsidiary of Carrier, which is widely regarded as an HVAC industry leader, and offers the same high quality without the high price tag.

Furnace Fuel Types: Natural Gas vs. Electricity vs. Oil

Natural Gas Furnaces

In Alberta, most of us heat our homes using natural gas. Our winters can be very long and very cold, and natural gas furnaces provide the heating muscle that we need efficiently and economically. In order to know if natural gas is the right fuel for you, you’ll need to know the benefits and drawbacks.


  • High heating efficiency. Natural gas furnaces have become increasingly efficient over the last decade. Some gas furnaces come with up to 98% annual fuel usage efficiency (AFUE) ratings.
  • Natural gas is the least expensive fuel for your furnace. It’s less expensive than both electricity and oil, and in recent years, the cost of natural gas has actually decreased.
  • Requires only minor, simple routine maintenance and cleaning.


  • Natural gas furnaces generally the have the highest initial cost to install.
  • Must be in an area where a gas supply is readily available.

Comfortmaker is reliable and efficient and offers a wide selection of some of the best natural gas furnaces.

Electric Furnaces

As people become more and more energy-conscious and work to lessen their consumption of fossil fuels, electric furnaces are gaining popularity. Also, while not all homes have natural gas hookups, most are likely equipped with electricity. However, while electricity poses some benefits, it also has its drawbacks.


  • Initial cost is generally lower than gas and oil furnaces, and the installation is quicker and easier.
  • Most durable and long-lasting type of furnace. Typically, lifespans range from 20-30 years.
  • Very easy and straightforward to maintain and operate.
  • Zero risk of gas leaks or explosions.


  • The cost to operate electric furnaces is greater. Your monthly energy bills will be higher than with a natural gas furnace.
  • Electric furnaces are less powerful and take longer to heat your house than natural gas furnaces.

Oil Furnaces

Oil furnaces aren’t as popular as they once were, but there are some people who still swear by oil heat. And, in some cases, oil can be the only choice, as some regions don’t have access to natural gas and electricity can be pricey. Oil furnaces have their own set of positives and negatives to consider.


  • Oil furnaces are easily and regularly serviced and maintained by the oil delivery company.
  • Using oil as fuel can cost less than using electricity to heat your home.


  • Fuel oil must be delivered on a regular basis, and a storage tank is required on your property. A service contract with an oil delivery company is likely required.
  • Maintenance and cleaning are much more extensive than other types of furnaces due to the build-up of soot from the burning oil.
  • Prices for fuel oil are high and rising, and oil furnaces are not as energy efficient as gas or electric furnaces.
  • More expensive than natural gas.

Comfortmaker offers a wide range of durable, reliable, and efficient oil furnaces. 

Whichever type of fuel you decide on, before making such a large investment in your home, be sure to consult a qualified HVAC professional like the ones you can find at Canuck Plumbing and Heating. There are often a range of different government and manufacturer rebate incentive programs, so make sure you do your homework.

Different Types of Furnaces

Single-stage Furnaces

A single-stage furnace operates in only one mode. It is either on or off. Either the furnace is running at its highest speed, blowing out as much hot air as it possibly can, or it’s off. These models are generally noisier and less efficient than other models. However, the initial cost of a single-stage furnace will likely be lower than other types of furnaces, and they’re easier and less expensive to install.

Two-stage Furnaces

Two-stage furnaces have two modes of operation. These models can operate at full speed, or a reduced speed, depending on the desired temperature and the demand for heat. Not only are two-stage furnaces quieter and more energy efficient than single-stage, but also they’re able to maintain a more consistent temperature in your home.

Modulating Furnaces

Modulating furnaces can continually adjust their running speed, heat output, and air velocity, based on the demand for heat. This makes modulating furnaces the most energy efficient option, as they only work exactly as much as necessary. The initial cost of a modulating furnace will be slightly higher, but it can more than make up for it by significantly lowering your monthly energy bills.

Choosing the Right Furnace Size for Your Home

Figuring out the appropriate size of furnace you need is crucial to cost and energy efficiency. A system that is larger than necessary will cycle on and off more frequently, wasting energy and money. On the other hand, not only will a furnace that’s too small fail to keep you consistently comfortable, but it will also waste energy by running continuously, and waste even more money by causing unnecessary stress on your heating system.

Furnaces come with different ratings that you’ll want to pay attention to including, BTU Input Capacity. BTU stands for British Thermal Units, and it’s the unit for measuring the amount of thermal energy required to raise a pound of water or one cubic foot by one degree Fahrenheit. Manufacturers often offer a range of different sized furnaces ranging from 40,000 – 120,000 BTUs. The BTU input capacity will help you determine whether or not the furnace is appropriately sized for the area you are trying to heat.

However, figuring out the best size is typically something that you’ll want to consult a heating professional to help you with. The proper size will be based off of “energy loss” calculations determined by the square footage of your home, level of insulation, number of windows, etc. One of our qualified Canuck Plumbing and Heating professionals will gladly help you figure out the proper size furnace best suited to your home.

Beware of buying a furnace based solely on the size of your home; it’s not a very accurate way of determining the best furnace for you. To figure out the ideal furnace size for you, the best thing to do is talk to one of our friendly and certified HVAC professionals at Canuck Plumbing and Heating.

Additional Links:

Pros and Cons of an Electric Furnace Versus Gas

How a Gas Furnace Works  

How to Size a Furnace

Chapter 3: Routine Furnace Maintenance

The most common cause of furnace problems is a build-up of dust and dirt. Your furnace is an absolute dust and dirt magnet, and if you allow it to accumulate, it can wreak havoc for your heating system. By keeping your furnace clean and doing some simple routine maintenance, you can extend the life of your heating system and allow it to run as efficiently as possible. 

Changing Your Furnace Air Filter

One of the simplest things you can do to ensure your furnace is running efficiently is to monitor the air filter for clogs, and change the filter on a regular basis. A clogged air filter can add unnecessary stress to your heating system, block the airflow, or even cause your furnace to shut down completely.

Not only does the air filter work to keep your furnace running smoothly, but it also filters the air we breathe. A properly functioning air filter will keep dust, dirt, hair, pet dander, and other allergens and debris out of your furnace, and also out of your lungs. Air filters are relatively inexpensive, and the cost of swapping out the filter every month or two is completely worth it to keep the air quality in your home healthy and your furnace running in tip-top shape.

There are a few telltale-warning signs that your air filter is in need of a change. 

Changing your furnace filter is easy with these simple steps:

Step 1: Determine the size of filter you need and purchase the filters. Consult your owner’s manual or check the filter that’s currently installed in your furnace for numbers on the side indicating the size (ie. 25x16x1).

Step 2: Turn off your thermostat. You don’t want your furnace turning on while you’re replacing the filter.

Step 3: Locate the air filter in your furnace, and remove the cover panel. On most models of furnaces, you’ll find the filter in between the supply and return air ducts, next to the blower assembly.

Step 4: Carefully slide out the old filter and put it in a garbage bag for disposal.

Step 5: Look at the side of the new filter and find an arrow. This arrow indicates the airflow direction. Ensure that the arrow is pointing in the correct direction – typically, it should be pointing towards the furnace.

Step 6: Slide in the new filter, replace the cover panel, and readjust the thermostat. Now, you’re all done!

Most furnace filters come with a “90-day” rating, meaning they can last for about 3 months. However, be sure to keep an eye on your filter. Based on where you live and how often you use your furnace, your filter may need to be changed more often. Keeping the filter clean is one of the simplest and most important things we can do to keep our air clean and our furnaces running smoothly and efficiently.

Cleaning Your Furnace Ducts and Vents

Duct cleaning can get kind of a bad rap. Unfortunately, there are a lot of fly-by-night duct cleaning companies that solicit their services door-to-door, offering 1-hour special deals or something similar, and then do little more than vacuum out your registers and vents. As long as you have a vacuum, you can (and should) keep your registers and vents free of dirt and debris by yourself.

It’s not something that has to be on your regular cleaning schedule, especially if you keep your furnace clean and swap out your air filter on a regular basis; however, if they’re dirty, cleaning out your vents, registers, and ducts can have a significant positive impact on your home’s indoor air quality.

Poor indoor air quality can trigger allergies, asthma symptoms, or other respiratory and sinus problems. If you notice a puff of dust coming out your registers every time your furnace turns on, or a thick, fuzzy build-up of dirt on your vents – or especially if you think there’s a clog or something stuck in your ducts – then it may be time to consider a professional duct cleaning.

Here are a few helpful tips for figuring out when it’s time to clean your ducts and vents.

Cleaning the Blower Assembly and Heat Exchanger

The number one cause of furnace problems and malfunctions is a build-up of dust, dirt, and debris. Even with the best furnace filters that money can buy, the blower assembly and heat exchanger block can become quite dirty and clogged with dust. Keeping your blower and heat exchanger clean can prevent your furnace from experiencing any problems and significantly extend its life.

How often your furnace will require a cleaning will vary depending on how frequently you’re using it, the climate, and the amount of dust and dirt in the air. Just keep an eye on your furnace and figure out a good routine to keep your entire central heating system nice and clean.

At Canuck Plumbing and Heating, we do not recommend cleaning the blower assembly or heat exchanger by yourself. There are lots of things that can go wrong if you attempt this. Instead, give us all call or better yet, join our Canuck Heat Club, so that we can come by and do the routine maintenance for you!

For a few simple maintenance tips to keep your furnace running in tip-top shape.

Additional Links:

How Do I Know When It’s Time to Replace My Furnace Air Filter

How Do I Know When It’s Time to Clean My Furnace Air Ducts?

4 Easy Ways to Keep Your Furnace Running in Tip Top Shape

Chapter 4: Furnace Troubleshooting

No matter how much preventative maintenance you do, your furnace isn’t perfect and it may experience some problems from time to time. There are a number of different things that can go wrong with your furnace, ranging anywhere from simple to serious, or even dangerous. But that doesn’t mean you have to call an HVAC professional every time you have a problem with your furnace. There are some quick fixes to some common problems that you’ll have no problem doing yourself.

WARNING: If you ever think your furnace has a gas leak, DO NOT try to fix it yourself. Immediately leave the house (leaving the door open) and find a safe location to call 911 or your local natural gas provider’s emergency line.

Carbon monoxide is an extremely dangerous gas that is produced any time we burn fuel and it poses serious risks to our health and safety, or possibly even death.

Start With Your Thermostat

You don’t want to start taking apart your furnace or scheduling a repair appointment when the real problem is with your thermostat. Your thermostat is the main control center for your furnace, so it should be the first place you look when you’re having furnace problems.

Troubleshooting your thermostat is simple. Here are some common thermostat problems and how to fix them:

  • First, check to make sure that the thermostat is set to the correct setting. Many thermostats have ON/OFF/AUTO settings. Choosing ON will allow the furnace to remain on, constantly recirculating air and reheating it when necessary. Choosing AUTO will allow the furnace to come on only when the temperature drops below the desired setting. Just be sure it’s not set to OFF.
  • Check to make sure there are no blown fuses or tripped circuit breakers. If you have a programmable thermostat, ensure the batteries are fresh. Your thermostat needs power if it’s going to be able to control your furnace.
  • Take off the cover of your thermostat and check the wiring for frays or loose connections, and check all of the metal contacts for corrosion or rust. With a very soft, dry brush carefully wipe off all the contacts and the bimetallic coil. Just a small layer of dust can cause your thermostat to malfunction.
  • Ensure that your thermostat is away from any heat sources and out of direct sunlight. Also, if you have a mechanical thermostat with a mercury bulb inside of it, it’s important that the thermostat is perfectly level on the wall.
  • Check to make sure the thermostat is controlling the furnace properly by adjusting the temperature up and down 5 degrees from the current temperature and listening for the furnace to turn on and off accordingly.
  • If the temperature of the room doesn’t seem to match the temperature on the thermostat, the problem may be with the heat anticipator, which should be properly set and adjusted by a qualified HVAC technician.

Troubleshoot your thermostat before assuming the problem is with your furnace and start taking things apart or calling to schedule a repair.

And of course, when in doubt, check the air filter. A dirty, clogged filter is one of the most common causes of furnace problems and malfunctions.

Not Enough Heat or No Heat At All?

Your furnace has one main job: to heat your home. So, obviously if your furnace isn’t producing enough heat or no heat at all, that’s a serious problem. Of course, the first thing you’ll want to do is check for a clogged filter or broken thermostat.

However, there are also several other possible causes for your furnace failing to heat:

  • Check all of your heat registers and vents to make sure they are clear. A build-up of hot air in your furnace can cause the sensors to malfunction, or even cause serious physical damage.
  • In the winter, go outside and make sure your exhaust vents aren’t covered with ice.
  • Check for blown fuses or a tripped circuit breaker on your home’s main electrical panel. You may have to swap out a blown fuse or reset the circuit breaker.
  • Ensure that your furnace’s cover panel is fully on and secured.
  • Be sure that your furnace’s power switch is on. It’s located near the furnace and looks like a light switch. Also, be sure that your gas is turned on if you have a natural gas furnace.
  • Most furnaces made in the last twenty years don’t have pilot lights, but if yours does, check to make sure that the pilot light hasn’t gone out. If it has gone out, relighting it is simple using the manufacturer’s instructions.

You certainly don’t want to go very long without heat, especially in our harsh Alberta winters. Be sure you know some simple tips for getting your heat going again. But the last thing you want is frozen pipes or a damaged HVAC system, so don’t wait too long to call in the professionals at Canuck Plumbing and Heating. We’ll bring the heat.

For a more in-depth guide on figuring out why your furnace isn’t producing enough heat.

Furnace Won’t Stay On or Keeps Turning On and Off?

When a furnace continually turns on and off, it is often referred to as short cycling. On average, your furnace should cycle on and off about 3 to 6 times per hour. In order to diagnose whether or not your furnace has a short cycling problem, count the amount of times your furnace stops and restarts over a 60-minute period.

If your furnace is turning on and off more frequently than 6 times an hour, and only staying on for a few minutes each time, your furnace is short cycling and needs to be fixed as soon as possible. Not only will short cycling cause your monthly energy bills to increase significantly, but it can also cause significant damage to your furnace and central heating system.

Short cycling is a fairly common problem, and it’s also usually easy to fix. One of the most common causes of a short cycling furnace is a clogged, dirty air filter. The number one thing you can do to keep your furnace running smoothly and efficiently is to change the filter on a regular basis. If the filter is clogged, the warm air will not be able to pass through and will become backed up inside the furnace, causing the sensors to think the house is warm enough, or that the furnace is overheating. This causes the furnace to shut off. However, the build-up of warm air will quickly dissipate and your furnace will turn on again, short cycling. So, when in doubt, check your air filter.

Sometimes, the problem isn’t with the actual furnace itself, but with the thermostat. Your thermostat controls your entire central heating system, so you should ensure that your thermostat is on and set to the proper setting (ie. ON or AUTO). And check to see if there are any frayed wires or corrosion on the thermostat. Also, the placement of the thermostat in your home can have an impact on the cycling of the furnace. For example, if your thermostat is placed near a heat register or in direct sunlight, this may cause your furnace to shut off prematurely. If your furnace is short cycling, you’ll want to be sure you’ve checked the thermostat before you call Canuck Plumbing and Heating for help.

But if you’ve checked your air filter and ruled out a broken thermostat, there are also a few other possible culprits:

Dirty, damaged, or corroded flame sensor – The flame sensor is a simple device located on the burner assembly. It’s a small, thin, bent metal rod that sits directly in front of the flames coming from the burner.

Blockage in ductwork or vents – Similarly to a clogged filter, a blockage in your ducts or vents can cause warm air to build-up in your furnace, causing the sensors to malfunction and the furnace to short cycle.

Improperly sized furnace – Obviously, if a furnace is too small, it will have to work harder to try to maintain the temperature, causing it to short cycle. However, a furnace that’s too large will also cycle on and off too frequently, possibly even more than a furnace that’s too small.

A step-by-step guide to figuring out the problem with your furnace.

Additional Links:

When Your Furnace Talks, Listen 

11 Signs Your Furnace Requires a Service Call 

Furnace Guide Summary:

If you’ve finished reading this guide, you can now consider yourself well on your way to becoming furnace savvy!

While you may need to call in a furnace expert every once in a while, you now know how to safely clean, maintain, and troubleshoot your home’s heating system.

You also know a little bit about the different types of furnaces out there, the different energy sources for heating your home, how to buy the right-sized furnace for your home, and ultimately, how to purchase the right furnace for you. It is a huge investment after all!

For all of your HVAC and furnace needs, you can count on Canuck Plumbing and Heating to have you covered! Call 587.803.1030 with any questions you may have or to book a service appointment.