Replace your furnace filter

 

Your forced air furnace filter plays an important role in maintaining the air quality in your home. Checking and replacing the furnace air filter is one of those chores most people know they're supposed to do, but few remember.

Usually when we do home inspections in the Ottawa area, there is a clean furnace air filter in the furnace and a very dirty one sitting next to the furnace. Hmmm ...

How often do furnace air filters need to be changed?

Depending on the quality of the filter, number of people, pets and amount of dust it could be monthly or every three months (for an average home).  The general rule is "If it looks dirty, it is dirty." 

Another way to determine when your furnace filter needs replacing is you could install an air filter gauge (General G-99 Air Filter Gauge Kit.). The G-99 Air Filter Gage provides a visual indication of the need to replace the air filters in forced air heating and cooling systems. The gage is installed between the furnace blower and the filter where a slight vacuum exists due to the air flow resistance of the air filter.

 

Why should you change the furnace air filter?

A dirty filter restricts airflow through your heating system. Reduced airflow can mean uneven heating or cooling, increased fuel bills, and possibly premature failure of your furnace due to the added stress of pulling air through the dirty filter.

                   

How to change the furnace air filter?

CAUTION: First locate the power shutoff for the furnace and turn it off  before you begin.

STEP #1 - Turn the furnace power off. Usually the switch is well marked in the stairway to the basement or near the furnace. (The Emergency Shut-off tags in the photo below are provided with every ib42 Ottawa Home Inspection)

Furnace (emergency) shut off switch

STEP #2 - Find the filter. It's usually where the cold air enters the furnace, near the fan section (see the diagram). At this location, the air is flowing into the furnace. The airflow arrow on the filter should point toward the furnace.

 

STEP #3 - Slide the filter out and note its size. It's written on it somewhere. See the photo below.

STEP #4 - Replace it as needed, but at least every three months. The rate at which they get dirty depends on the number of people, pets and amount of dust in your home.

STEP #5 - Turn the furnace power back on.

TIPS:

• Mark airflow direction on the duct work with a marker so that it will be easier to remember the orientation of the filter the next time.   
• Mark the date on the side of the filter as a reminder of the last change.



Furnace air flow, note arrow on filter is the same direction

Furnace air flow, note date on filter

Furnace Filters Information and References

Some useful information about furnace filters from the EPA.

Furnace filters are rated by Minimum efficiency reporting value (MERV) and here is a chart

How to choose the right furnace filter

YouTube Video  (Note: Make sure to turn the furnace power off first and then back on after!)

GOVERNMENT OF CANADA PUBLICATIONS
http://publications.gc.ca/collections/Collection/NH18-24-22E.pdf

NRCAN
http://www.nrcan.gc.ca/science/expert/video/1503?destination=node/6708

STATISTICS CANADA
http://www.statcan.gc.ca/pub/16-002-x/16-002-x2012001-eng.pdf (stat on furnace changes)

CITY OF TORONTO
Indoor Air Fact sheet
http://www.toronto.ca/health/hphe/pdf/indoor_air_factsheet.pdf

AMERICAN LUNG ASSOCIATION
“Air Cleaning Devices”
www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=35696

ASSOCIATION OF HOME APPLIANCE MANUFACTURERS
A website on portable air filters and the ANSI / AHAM AC-1 Clean Air Delivery Rate (CADR) approach.
www.cadr.org

CALIFORNIA AIR RESOURCES BOARD
“Air Cleaner Devices for the Home: Frequently Asked Questions” An overview of considerations when purchasing a filter.
www.arb.ca.gov/research/indoor/aircleaners.htm

CANADA MORTGAGE AND HOUSING CORPORATION (CMHC)
“Your Furnace Filter”
www.cmhc-schl.gc.ca/en/co/maho/gemare/gemare_008.cfm

www.cmhc-schl.gc.ca/odpub/pdf/61607.pdf

CONSUMER REPORTS
Objective information on the performance of specific models, as well as general advice.
www.consumerreports.org/cro/index.htm

FOR INFORMATION ON ASTHMA CONTROL
www.asthma.ca and www.cmhc.ca/en/co/maho/yohoyohe/inaiqu/inaiqu_005.cfm

HEALTH CANADA
“Warning - Health Canada warns the public about air cleaners designed to intentionally generate ozone” This publication includes a list of affected ozone generator brands and models.
www.hc-sc.gc.ca/ahc-asc/media/advisoriesavis/1999/1999_62_e.html

LOW-POLLUTION PRODUCTS
Healthy Indoors Partnership (HIP) will prepare a separate consumers’ guide to finding and buying low-emission products and services. In the meantime, we suggest the following helpful sites:
www.oikos.com and www.cmhc.ca/en/co/maho/yohoyohe/inaiqu/inaiqu_006.cfm

NATIONAL AIR FILTRATION ASSOCIATION
Provides technical guides to MERV ratings and air filtration.
www.nafahq.org

Inspected by 42 Home Inspections - Kanata and Ottawa surrounding area

Ottawa Home Inspections