When wildfire smoke settles over the Fraser Valley, homeowners often have to manage two problems at once. The outdoor air is poor, but the house can still get uncomfortably hot, especially during an August afternoon in Chilliwack or Abbotsford.
Closing your windows is a good first step, but your HVAC settings, filter, ventilation equipment, and portable air cleaner can also affect the air inside. We help homeowners manage cooling and airflow through our professional air conditioning services, with support available across Chilliwack, Abbotsford, and surrounding Fraser Valley communities.
You don’t need to understand every part of the system before smoke arrives. You do need to know which settings are safe to change, whether the filter suits the equipment, and which warning signs point to an airflow or cooling problem.
How Wildfire Smoke Gets Into a Closed Home
Wildfire smoke contains gases and very small particles. Fine particulate matter, commonly called PM2.5, is the main health concern because it can travel deep into the lungs. The BC Centre for Disease Control’s wildfire smoke guidance explains how smoke exposure can irritate the eyes, nose, throat, and lungs, especially for people with existing health concerns.
Your windows don’t have to be open for smoke to get inside. Outdoor air can move through gaps around doors, windows, attic openings, exhaust vents, and other parts of the building. A heat recovery ventilator, energy recovery ventilator, or dedicated fresh-air intake can also bring outdoor air inside during normal operation.
You’ll sometimes smell smoke before you can see haze indoors. Odour doesn’t show exactly how many particles are present, so it shouldn’t be your only guide. Check the Air Quality Health Index for your area while conditions are changing, and follow local public-health information throughout the day.
Does Your Air Conditioner Bring Smoke Inside?
A standard central air conditioner doesn’t normally pull air through the outdoor condenser and send it into your rooms. The outdoor unit releases heat from the refrigerant circuit, while the indoor blower moves air through the duct system.
Smoke can still enter through separate ventilation equipment, an open fresh-air damper, building leaks, or frequent door use. Turning off a working central AC can leave the house hotter without addressing the route smoke is using to get inside.
HVAC layouts vary across Fraser Valley homes. Some homes use a furnace and central air conditioner. Others rely on a heat pump, an air handler, or separate ventilation equipment. Older Chilliwack and Abbotsford homes can also have equipment that has been updated in stages, so the thermostat, filter cabinet, and ventilation controls don’t always come from the same installation.
If you don’t know which controls bring in outdoor air, don’t start closing dampers or disconnecting equipment. We can inspect the HVAC setup and explain which controls affect cooling, circulation, and outdoor-air intake.
Start With a Clean, Compatible HVAC Filter
Your central filter can only help when air passes through it. A filter that’s damaged, installed backward, heavily loaded, or surrounded by gaps won’t perform as intended.
Check the filter before smoke arrives. Our guide to HVAC maintenance for Chilliwack homeowners covers regular filter checks along with other steps that support airflow and reliable system operation during heavy seasonal use.
Check Efficiency, Fit, and Airflow Together
MERV stands for Minimum Efficiency Reporting Value. A higher rating generally means the filter can capture smaller particles, but higher-efficiency filters can also create more resistance to airflow.
Health Canada recommends using the highest MERV rating your HVAC system can support, with MERV 13 or higher recommended for fine particles when the equipment can handle the added resistance.
The number on the filter package isn’t the only factor. Older forced-air equipment often uses a shallow filter cabinet, while newer systems can use a deeper media filter or a different return-air arrangement. A restrictive filter in the wrong system can weaken cooling, increase run time, and contribute to coil icing.
The filter should fit securely without large spaces around the frame. Air takes the easiest route, so a loose filter can allow air to move around the filter material instead of through it.
Most disposable filters have an arrow printed on the frame. That arrow should point in the direction of airflow, normally toward the furnace or air handler.
During a prolonged smoke event, inspect the filter more often than usual. Colour alone doesn’t tell you whether it’s restricting airflow. Follow the manufacturer’s replacement schedule, and replace any filter that’s damaged, heavily loaded, or affecting system performance.
Use Recirculation Carefully
Recirculation keeps indoor air moving through the system instead of continually introducing outdoor air. During smoky conditions, this can reduce the amount of unfiltered outdoor air entering through mechanical ventilation.
The control could be on your thermostat, HRV controller, ERV controller, or fresh-air damper. Labels aren’t always clear, and two homes with similar heating and cooling equipment can still have different ventilation setups.
Before smoke season, learn how your controls handle outdoor air. During poor air quality, Health Canada advises recirculating indoor air where the system allows it, then bringing in cleaner outdoor air after the smoke has moved away.
Should You Leave the HVAC Fan Running?
A thermostat’s “on” or “circulate” setting can move more indoor air through the central filter. This can help when the system has a suitable filter and good airflow.
Continuous fan operation isn’t the right choice for every system. It uses electricity, and the result depends on the filter, blower, ductwork, and thermostat controls. If airflow is already weak, running the fan longer won’t correct the restriction.
An inspection before heavy summer use gives you time to address those concerns. In our article about AC maintenance before summer in BC, we explain how filter condition, airflow, electrical components, thermostat settings, and outdoor equipment all contribute to dependable cooling.
Keep the Home Closed Without Letting It Overheat
Keep exterior windows and doors closed while outdoor smoke levels are high. Check that windows latch and doors seal properly, especially where worn weatherstripping leaves a visible gap.
Don’t ignore indoor temperature. A closed home can heat up quickly during a Fraser Valley heat event, and inland communities such as Chilliwack and Abbotsford can stay warm well into the evening. The BCCDC advises using air conditioners, heat pumps, fans, and window coverings to keep a cleaner-air space comfortably cool.
During hot, smoky weather:
- Close windows and exterior doors while outdoor air quality is poor.
- Use blinds or curtains to reduce direct afternoon sun.
- Run suitable cooling equipment before the house becomes excessively warm.
- Limit unnecessary trips through exterior doors.
- Move to a cooler public space if the home can’t stay at a safe temperature.
Libraries, community centres, and shopping centres can offer cooler indoor air during combined heat and smoke events. Anyone with a chronic health condition should follow advice from their healthcare provider and local public-health authorities.
If your air conditioner is running but the house keeps getting warmer, don’t assume smoke is responsible. A clogged filter, dirty coil, electrical problem, refrigerant issue, or undersized system can also reduce cooling performance.
Set Up One Cleaner-Air Room
Filtering the entire house isn’t always practical. One comfortable room can give your household a place to spend time while outdoor conditions are poor.
Choose a bedroom or living room with:
- A door that can remain closed
- Few exterior windows or doors
- Working cooling or another safe way to control temperature
- Enough space for the people using it
- A portable air cleaner sized for the room
A portable air cleaner works best when its airflow matches the room size. Health Canada recommends checking the room-area rating and Clean Air Delivery Rate, often shown as CADR, before buying a unit.
Choose a Portable Air Cleaner That Fits the Space
HEPA stands for high-efficiency particulate air. Many effective portable cleaners use HEPA filtration, but the filter label alone doesn’t show whether the machine can clean a large room quickly enough.
The Health Canada guide to portable air cleaners recommends choosing a unit based on room size and smoke CADR, with higher fan speeds and longer run times providing more air cleaning.
Place the cleaner where walls, curtains, and furniture won’t block the intake or outlet. Keep the room’s doors and windows closed while outdoor air is smoky, and replace the portable filter according to the manufacturer’s directions.
Avoid air cleaners designed to generate ozone. Ozone can irritate the respiratory system, so it isn’t suitable for an occupied cleaner-air room.
Our indoor air quality guide also covers filtration, ventilation, humidity, and other conditions that affect the air inside a home throughout the year.
Reduce Particle Sources Inside the Home
Outdoor smoke isn’t the only source of indoor particles. Cooking, candles, incense, smoking, wood-burning appliances, and dust can add particles while the central filter or portable cleaner is running.
During heavy smoke:
- Choose cooking methods that produce less smoke.
- Skip candles, incense, and indoor wood fires.
- Damp-dust hard surfaces instead of dry dusting.
- Wet-mop floors when practical.
- Use a vacuum with effective filtration if vacuuming can’t wait.
A strong kitchen or bathroom exhaust fan can depressurize the house and pull outdoor air through small openings. Use necessary ventilation, but don’t leave powerful exhaust equipment running longer than required.
Give the Outdoor AC Unit Room to Breathe
The outdoor condenser needs clear space around the cabinet so it can release heat. Leaves, grass clippings, ash, and other debris can collect around the unit during summer.
Turn the system off before removing loose debris from the surrounding area. Don’t remove access panels, reach inside the cabinet, or spray electrical controls.
Professional maintenance goes beyond cleaning the visible exterior. We inspect system operation, review airflow, check controls, and look for signs of wear. Homeowners comparing repair and replacement options can also review our home comfort equipment information, which includes the equipment brands we work with.
Signs Your HVAC System Needs Professional Attention
A filter change or thermostat adjustment shouldn’t cause a major drop in cooling performance. Call us when you notice:
- Weak airflow from several vents
- Ice on the refrigerant line or indoor coil area
- Water collecting near the furnace or air handler
- A filter bending or collapsing in its slot
- New grinding, squealing, rattling, or electrical sounds
- Repeated breaker trips
- The system running continuously without cooling the home
- A strong burning or electrical smell
Turn the equipment off if you see smoke coming from the system or smell a strong electrical burning odour. Don’t remove panels or attempt electrical repairs.
What to Do When the Outdoor Air Clears
Once outdoor air improves, check local readings before opening the house. Bring in fresh air when outdoor conditions and temperatures are suitable, especially if the home has been closed for several days.
Inspect the central HVAC filter and the portable air cleaner’s filter. Replace either one when it’s loaded, damaged, or due according to the manufacturer’s instructions.
Smoke particles can settle on floors and furniture. Damp-wipe hard surfaces and clean floors without stirring up unnecessary dust. You can keep the portable cleaner running while you work.
Reset any ventilation controls that were changed during the smoke event. Leaving an HRV, ERV, or outdoor-air intake in the wrong mode after the air clears can affect normal ventilation.
Prepare Before the Next Smoke Event
A short check before an advisory begins gives you more control once smoke reaches the region.
Keep these steps with your summer home-maintenance notes:
- Confirm the correct central filter size.
- Check which MERV rating the equipment can support.
- Keep a suitable replacement filter available.
- Learn how the HVAC controls handle outdoor air.
- Test the portable air cleaner.
- Choose one room for cleaner-air use.
- Check door and window seals.
- Monitor official air-quality information.
- Book service when airflow or cooling performance changes.
If airflow drops or the home won’t stay cool during smoky weather, our Chilliwack heating and cooling team can inspect the system and explain what’s affecting performance. Homeowners closer to Abbotsford can also reach us through our Abbotsford service location for the same clear, professional support.
Get Clear HVAC Guidance From Our Team
We’re proudly based in Chilliwack, and we provide fast, transparent, high-quality heating and cooling service across the Fraser Valley and Lower Mainland. Our technicians can inspect the filter setup, review airflow, test cooling performance, and help you understand the HVAC controls connected to the system.
You’ll get clear information about what we find and practical options based on the equipment’s condition. We won’t ask you to rely on a filter upgrade or thermostat setting the system isn’t designed to support.
To ensure your equipment is ready for hot, smoky weather, contact our team and tell us what you’ve noticed. We’ll help you protect indoor comfort while keeping your cooling system working safely and reliably.
