Wildfire Smoke Playbook for New Hampshire Homes

Wildfire smoke can affect New Hampshire even when the fire is many miles away. During a smoke event, the goal is to reduce the amount of outdoor smoke entering the house and filter the indoor air without creating new indoor pollution. A.J. LeBlanc Heating can help homeowners understand how their HVAC equipment, filtration, ventilation, and thermostats should be used.

Watch the local air-quality forecast

Check the AirNow Air Quality Index and follow public-health guidance for your area. Conditions can change during the day, so the right response depends on the current outdoor air quality and the needs of the people in the home.

When outdoor air is smoky, keep windows and doors closed as much as practical. Avoid activities that add particles indoors, including smoking, burning candles, frying food, and unnecessary vacuuming. When the outdoor air improves, air out the home if conditions allow.

Set central HVAC equipment to recirculate

Most central air-conditioning systems recirculate indoor air, but some systems and ventilation controls bring in outdoor air. During a smoke event, close or reduce the outdoor-air intake when the equipment and manufacturer's directions allow it. Set the system fan to run more often so air passes through the filter, provided the system can operate that way safely and effectively.

Homes with an energy-recovery ventilator or heat-recovery ventilator may need a temporary setting change. Follow the manufacturer's instructions or ask the installer how to limit smoke entry. Remember to return the ventilation system to its normal setting after the event.

Use the best filter the system can support

EPA recommends a MERV 13 filter, or the highest-efficiency filter the system can accommodate. A higher-rated filter can restrict airflow if the equipment and ductwork were not designed for it. If you are unsure, A.J. LeBlanc Heating can check the filter size, cabinet, airflow, and equipment requirements before you make a change.

Inspect the filter during extended smoke conditions and replace it when it is dirty or according to the manufacturer's instructions. A filter cannot help if air is bypassing the cabinet, so fit and sealing matter as much as the label.

What about mini splits?

Most ductless mini splits recirculate room air rather than drawing in outdoor air, but the exact operation depends on the equipment. Their washable mesh filters protect the equipment and capture larger dust. They are not a substitute for a filter or portable air cleaner designed to capture fine smoke particles.

Keep the mini split clean and follow the manufacturer's maintenance directions. If smoke odor or residue remains after conditions improve, schedule service before assuming the system needs aggressive cleaning.

Create a cleaner-air room

EPA recommends creating a cleaner-air room when smoke is expected to last. Choose a room where you can keep windows and doors closed, and use a portable air cleaner sized for that room. Compare the current product label and Clean Air Delivery Rate rather than relying on a marketing description alone.

Avoid air-cleaning devices that intentionally produce ozone. Ozone is a lung irritant and is not a safe way to remove smoke from occupied rooms.

How A.J. LeBlanc Heating can help

Check whether the central system can use a higher-efficiency media filter
Inspect filter fit, cabinet sealing, and system airflow
Review thermostat and fan settings for the equipment
Explain how installed ventilation equipment should be managed
Service whole-house filtration and indoor-air-quality equipment

We focus on the equipment and controls we can verify in the home. If someone in the household has a medical condition or symptoms related to smoke exposure, follow guidance from a healthcare professional and local public-health officials.

Frequently asked questions

Should I turn off my air conditioner during wildfire smoke?

Not necessarily. Most central systems can continue cooling while recirculating indoor air. The important step is to limit outdoor-air intake when the equipment allows it and use a compatible filter. Check the manufacturer's instructions or ask an HVAC professional if you are unsure.

Should I turn off my ERV or HRV?

These systems bring outdoor air into the home, so a temporary setting change may be appropriate during heavy smoke. Follow the manufacturer's directions or ask the installer. Restore normal ventilation after outdoor air quality improves.

Is a MERV 13 filter safe for every HVAC system?

No. MERV 13 is a useful target, but the system must have enough airflow with the selected filter. Use the highest-efficiency filter the equipment can support and have the system checked if you are uncertain.

Do mini split filters remove wildfire smoke?

The standard washable filters in most mini splits are not designed to replace smoke-particle filtration. A properly sized portable air cleaner can provide additional filtration in a closed room.

Sources

Last reviewed July 2026.

Need help preparing your HVAC system for smoke? Contact A.J. LeBlanc Heating. We can review your filtration, airflow, thermostat settings, and installed indoor-air-quality equipment.

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