To serve you better, we remain open 24/7 during the COVID-19 outbreak. Learn More

Find the Do-It-Yourself Solution to Your Furnace Problem

With some basic knowledge of how your home appliance works and minimal do-it-yourself experience, you might be able to fix your  furnace problem yourself.

Our step-by-step guide is here to provide you with the knowledge and confidence it takes to tackle any common furnace problem yourself. If at any point when following this guide you don’t feel comfortable or experienced enough to solve your furnace problem then it is in your best interest to schedule a service call with a professional HVAC technician to avoid a dangerous situation for yourself, your equipment, and your home.

Here are the most common furnace problems and how to fix them.

Make sure your thermostat is ON

Although it seems like a no brainer, you’d be surprised at the amount of service calls that are made without homeowners checking if their thermostat is on.

Make sure your home’s thermostat is on, set to “heat”, and is at least a couple degrees above room temperature.

Here are a few other thermostat ways you can fix a thermostat related furnace problem:

  • You may need to change the batteries in your thermostat. If your thermostat runs on batteries, they should be changed once a year. Thermostats that use batteries often flash a low-battery symbol when it’s time for a replacement.
  • Check if the breaker is in. If it is, turn it off and check the furnace fuse.
  • Make sure that the date and time on the thermostat are correct. Your thermostat may be on a timer, so the date and time are important to its operation.
  • Open up the thermostat and blow out the dust and debris inside. A dry cloth can also be used to clean the inside of the device.

Furnace not producing any heat

First off, check to make sure that the thermostat is on the “heat” setting. Now try adjusting the temperature a couple degrees up or down and see if you feel a difference.

If no difference is felt, check to see if the furnace’s fuse or circuit breaker are blown.

Testing the circuit breakers:

  • Go to the breaker panel in your home and find the circuit that controls the furnace.
  • Test the breaker by flipping it back and forth.
  • Make sure it stays in the “on” position.

Following these steps should reset the breaker. If it doesn’t, then the problem is to do with the circuit breaker itself or the wiring in the circuit.

Furnace isn’t producing enough heat

If your furnace isn’t heating your home as well as it used to, the furnace problem is often to do with a dirty, clogged air filter. Check your furnace filter to ensure that it is in good condition, if not then follow the steps below on how to change a dirty furnace filter. Replacing your furnace filter is easy and will greatly improve your furnace’s efficiency and your home’s air quality. A clogged filter restricts airflow and forces your furnace to exhaust itself by working harder to heat your home.

Steps to follow when checking and changing your furnace filter:

  • Locate the filter. Filters are either located in the furnace intake, which looks like a grate in the wall, floor, or ceiling, or it’s located within the furnace itself.
  • Evaluate the filter’s condition. Checking the filter can be done by holding it up to the light. If you don’t see any light pass through it then it’s time for a replacement.
  • Replace the filter. Turn off your furnace before you get started. You will know that it has been successfully turned off if there is no air coming out. Check the direction the filter points and make sure you put it in right-side up.

Check the pilot light or electric ignition

A malfunctioning ignition system won’t allow for your furnace to heat the house properly. Your furnace’s pilot light will often go out if there is a clog somewhere in your heating system.

Your furnace might not have a pilot light and may instead ignite electronically. This is typical for newer furnace models.

How to check and fix a faulty ignition system:

  • The ignition might need to be reset. Reset the ignition by powering down the furnace and turning it back on by flipping the power switch off and back on.
  • Now turn off the furnace and the gas before checking the heating element for damage. Do not touch the heating element, but visually inspect it for any cracks or damage. If you spot any damage then the ignitor needs to be replaced.
  • The manual that comes with your furnace from the manufacturer includes a step-by-step guide on how to troubleshoot this problem. Follow the steps carefully as damage can be done to your equipment and your home if any steps are skipped.
  • If following the steps given by the manufacturer does not resolve the issue, call a professional HVAC technician to solve your furnace problem.

Check burners for debris

A furnace problem we often see is burners that are contaminated and filled with debris. You can check if your burners are clean by taking a look at the burner flames.

If the burner flames are blue then the burner is clean. If the flame burns yellow then that’s an indicator of dirty furnace burners.

Burners can be cleaned using a vacuum cleaner. Before getting started, turn off the power and gas. Use the vacuum to clean up any debris on and around the burner.

It’s important that you clean the furnace burners before the heating season as dust and debris tend to accumulate over the summer. Contaminated burners can lead to numerous other serious furnace problems. If the burners are in very bad condition then they should be replaced by a professional technician.

Furnace isn’t blowing any air

Look through the inspection window of the furnace and see if the blower is being obstructed by anything. There is a light which indicates the status of the blower; it flashes either red or green. The furnace manual should indicate what each colour means.

Usually, green means that the blower is working fine, while red means that you’re in need of a service call.

If the light is not flashing at all then the furnace problem is likely to do with either the blower motor, thermostat, furnace control board, transformer, or run capacitor.

Furnace turning on and off again too quickly

This furnace problem is called rapid cycling and there are many causes which lead to it. A common cause and the one easiest to resolve is having a dirty and clogged furnace filter. Try replacing your clogged furnace filter with a brand new one to resolve this issue. You can find them steps to changing your furnace filter listed above.

If replacing the furnace filter doesn’t solve the problem then you should call a professional HVAC technician for a service call as it may be a serious problem.

Gas furnace blower running nonstop

A furnace that never turns off can be a sign of a necessary repair. Before assuming the worst, there are some steps you can take to see if the problem can be solved without a repair.

First off all, make sure that your thermostat isn’t set to the “continuous fan” setting. Next, try turning down the temperature by a degree or two as this may solve the problem.

This could be a sign of a broken limit control switch, meaning that it needs to be replaced or reset.

Flame sensor is dirty

The flame sensor protects your furnace from the unsafe burning of fuel. If the flame sensor is dirty it won’t allow your furnace to run properly. The flame sensor looks like a rod and is located at the back of the furnace.

Steps for cleaning the sensor:

  • Turn off the furnace
  • If you can, remove the flame sensor from the furnace
  • Scrub the sensor gently with a cloth to remove any residue
  • Reattach the flame sensor to the furnace
  • Turn the furnace back on

Loud noises coming from furnace or ductwork

Your furnace and ductwork can make a whole bunch of odd noises, some of which are a sign of a potential problem. The problem can range from being a clogged burner, an airflow reduction, or a mechanical problem.

If you can tell that the sounds are a result of the air running through then adding some insulation to the ductwork should make the noise go away.

If it’s the furnace itself making odd sounds then it may be that the blower motor points need to be lubricated or that the pilot light isn’t properly adjusted.

A number of other problems could also be causing the sounds you’re hearing, here are some of them:

  • Popping sounds: this could be the ductwork expanding and contracting as it heats up and cools back down.
  • Rattling sounds: this could be that there are loose panels in need of tightening.
  • Squealing sounds: this could be that there is a belt which connects the motor to the fan that has slipped. It could also mean that there is a belt that needs to be replaced.
  • Grinding sounds: The motor bearings need to be repaired. Make a service call to a professional HVAC technician for a repair.

Smelling gas – potential gas leak

If you have the smell of gas in your home and suspect that there is a gas leak then you should IMMEDIATELY evacuate your home along with all of your family members and contact your gas utility company.

If you live in Ontario in GTA and Ottawa you need to call Enbridge Gas Distributions at 1-866-763-5427, 24 hours a day, 7 days a week.

Outside of GTA and Ottawa you will need to call your local gas utility in many cases it is Union Gas 1-877-969-0999

A gas leak will affect the operation of your furnace, but more importantly it poses a significant threat to the health of you and your family.

Furnace has reached the end of its life

Unfortunately, after many years of service to you and your family, your furnace will reach the end of its life. This will be indicated by a significant decline in efficiency and an overall worse performance. If the furnace has outlived the manufacturer’s warranty then you are likely not experiencing its peak performance any longer.

If you have a particularly old furnace in your home then it may be time to replace it for a brand new high efficiency model.


We hope that these tips help you in solving your furnace problem, if not then we suggest that you have a professional HVAC technician take a look. If you have any further questions regarding a furnace problem you’re experiencing or have any other HVAC concerns, don’t hesitate to contact us at any time. Our highly trained and experienced technicians are more than prepared to assist you with any of your HVAC problems. We provide efficient and quick furnace replacement done by our team of HVAC professionals. We offer a variety of furnace rental, purchasing, and financing options.

Give us a call at 1 (855) 998-2998 or fill out our online request form and we will be happy to assist you with your request.

Easy Rentals...

get total piece of mind with our High Efficiency Furnace and Air Conditioner Rental Program.
Customer Rating of 5.0
based on Google reviews

  • Get A Quote Today! Free in-home estimate!
  • This field is for validation purposes and should be left unchanged.

Upgrading to a high-efficiency heating and cooling system offers more than energy savings.

Take advantage of these rebates today!


This item comes with absolutely free standard installation. We’ll ensure that the product is completely installed to code and fully functioning prior to leaving.


Great news! Receive a brand new digital thermostat absolutely free when renting this HVAC product from DeMark Home Ontario.


Great news! When renting a furnace or air conditioner, you’ll get your first 2 months absolutely rent free.


Great news! When renting a furnace and air conditioner together, you’ll get your first 3 months absolutely rent free.


This product carries a manufacturer warranty and we’re happy to explain it in full to you. Feel free to get in touch with us for more information or see the Warranty Information tab for more information


If your order is placed and confirmed by 11am, we can have your HVAC product installed within the same day.

Certain conditions apply, not available on all products.


This water heater is subject to reduced rental rates based on the DHO discount program. Save money on your bill every single month!

Some conditions apply


Save money on this item when buying it along with a qualifying high-efficiency furnace or air conditioner.

Some conditions apply


Great news! When renting a qualifying water heater, you’ll get your first 2 months absolutely rent free.


Promotional code can be found on the eFlyer, Brochure or promotional email that you received from us.

*If you are an existing customer please refer to the mail or email that was sent to you after the installation of your equipment as it contains your promotional code. If you are having troubles locating it please call us and one of our Customer Service Representatives will be happy to assist you.

  • Please fill out the form below in order to schedule service and be sure that your request will be processed promptly and you will hear back from us shortly.

Notice for Power Vent Water Heater Customers

Effective August 2007, gas code requires technicians working on venting to replace black ABS vent pipe with white UL-certified vent pipe.

We will upgrade your venting pipes at no additional cost.

  • Forum Registration

  • Forum Rules

    Registration to this forum is free!
    You must abide by the rules and policies detailed below. If you agree to the terms, please check the 'I agree' checkbox and press the 'Register' button below.

    Although the administrators and moderators of DeMark Home Ontario Forum will attempt to keep all objectionable messages off this forum, it is impossible for us to review all messages. All messages express the views of the author, and DeMark Home is not responsible for the content of any message.

    By agreeing to these rules, you warrant that you will not post any messages that are obscene, vulgar, sexually-oriented, hateful, threatening, or otherwise violative of any laws.

    The owners of DeMark Home Ontario Inc reserve the right to remove, edit, move or close any thread for any reason.



Send this to a friend