Furnace and AC Filter Replacement in Mississauga
In most Mississauga homes, the furnace and the central AC share one filter. We fit the right size the right way round, check the slot for gaps, and tell you how often yours needs changing.
Request Filter Replacement
Send the details and Real Deal HVAC will follow up.
One filter does two jobs.
Your furnace and central AC push air through the same filter. When it clogs, both systems struggle.
- Less airflow. Rooms far from the furnace stop getting enough heat or cooling.
- A furnace that overheats. In winter, a safety switch shuts the burners off, so the furnace runs in short bursts.
- An AC that freezes up. In summer, too little air can freeze the cooling coil that sits on the furnace.
- More dust. A full or loose filter lets dust past, into the blower and back into your rooms.
- More wear. The blower has to work harder to pull air through.
What happens on a filter visit.
It is a small job, but we do more than swap the filter.
- Right size and type. We match the size on the old filter, or measure the slot if it is missing. Then we pick a grade your system can pull air through easily.
- Right way round. The arrow on the frame points toward the furnace, the way the air moves.
- No gaps. We check the slot or cabinet for gaps that let air slip around the filter.
- A look at the old one. How dirty it is tells us how fast your house fills a filter.
- Your schedule. We tell you how often yours needs changing.
How often to change it.
It depends mostly on how thick the filter is. The thickness is the last number printed on the frame.
- 1 inch filters. Usually every 1 to 3 months. These slide into a slot at the furnace.
- 4 or 5 inch media filters. Usually every 6 to 12 months. These sit in their own cabinet beside the furnace.
- Sooner than that if you have pets, allergies or asthma in the house, renovation dust, or you run the fan all the time.
Winter and summer are the heavy months in Mississauga, because the system runs the most. For more detail, read our furnace filter guide.
Signs your filter is overdue.
- You cannot see light through the filter when you hold it up
- Some rooms never get as warm or as cool as the rest
- The furnace or AC turns on and off in short bursts
- Dust settles again a day or two after you clean
- A whistling sound from the return vent, the big grille that pulls air back to the furnace
- Ice on the copper pipe near the furnace in summer. Turn the cooling off and call us
Better ways to get cleaner air.
Forcing a denser 1 inch filter into the slot can choke the airflow. If you want cleaner air, these work alongside your filter.
- A HEPA filter in its own housing, for very fine dust and allergens
- A whole-home air purifier that works with your furnace
- A UV light inside the system, to help keep mould off the AC coil
Easiest of all: have the filter done on the same visit as a furnace tune-up, an AC tune-up or a maintenance plan visit.
Filter overdue, or not sure what size you need?
Call or send the form and we will fit the right filter and tell you how often to change it.
Rather just talk? Call (647) 280-6626. We answer any hour. Licensed and insured, and you agree the price before any work starts.
Furnace and AC filter replacement FAQs.
Can you replace my furnace filter during a tune-up?
Yes. On every furnace tune-up, the filter is checked and replaced if it needs it. Our AC tune-up checks it too. If the filter is all you need, you can book a filter visit on its own.
Do the furnace and AC use the same filter?
In most Mississauga homes, yes. Central air uses the furnace fan to move cool air, so heating and cooling pull air through the same filter. That is why it needs changing in summer too. Ductless mini splits are different. Each indoor unit has its own washable filter.
What size furnace filter do I need?
Look at the edge of your old filter. The size is printed there as three numbers, such as 16x25x1. That is width, height and thickness. If the filter is missing or the print has worn off, we measure the slot and find the size that fits.
Can a dirty filter make my AC freeze up?
Yes. The AC coil needs a steady flow of house air. A clogged filter cuts that flow, the coil gets too cold and ice forms. You may see ice on the copper pipe near the furnace, or water on the floor. Turn the cooling off and change the filter. If it freezes again, book AC repair.
Can a dirty filter stop my furnace from working?
It can. With too little air, the furnace overheats and a safety switch shuts the burners off. It may start, run a few minutes and stop, over and over, while the house stays cold. Change the filter first. If it still will not heat, book furnace repair.
What should I have ready for a filter replacement visit?
The size printed on your old filter, if you can see it. A photo of the filter edge works well. Also tell us about pets, allergies or recent renovation work, because they change how often your filter needs replacing.
Should I change my furnace filter myself or have you do it?
A 1 inch filter is easy to change yourself. Slide the old one out and the new one in, with the arrow pointing toward the furnace. Call us when the size is a mystery, the filter does not sit snugly, you have a thick media cabinet, or you want it done with a tune-up.