Get the Most From Your Heating and Air Conditioning Filters When You Use a GeneralAire G99 Air Filter Change Indicator

by Don Munn

Rate this post

One of the problems with furnaces, heat pumps and air conditioners is that they don’t come with filter service indicators. With an air filter change indicator you would know for certain when your air filter has reached it’s tipping point, the point where there is greater value in changing the filter than there is in leaving it in the system.  Without the proper equipment to monitor air flow, the particle count of the air, operating pressures, power consumption and run times, there is no accurate way for you, the home owner, to be certain that it is time to change your furnace filter or air conditioner filter.

At best, it is a guessing game and all you can do is follow manufacturers recommendations or set your own schedule. Many home owners rely on filter change indicators on their thermostats but these are only timers and don’t actually monitor the system. They simply indicate a filter change is required after so many hours of operation. This is fine if your environment never changes. But as seasons change so does the amount of dust and allergens in the air. Then there is construction, pollution and other things that we don’t even think about.

A possible solution for home owners

G-99-air-filter-change-gage

I have worked in the HVAC industry for twenty years and I have used equipment that solves this problem but these are commercial applications and not practical for residential use, until now. I recently came across this little device. It’s a G99 Air Filter Gage manufactured by GeneralAire and it’s made for residential use.

How it works

The GeneralAire air filter gage mounts on the side of your air handler and senses the air pressure between the air filter and the blower fan. A slight vacuum exists between the air filter and the fan at all times. The vacuum is created because the fan is pulling air through the filter. As the filter becomes dirty air flow restriction increases and the vacuum that exists between the air filter and the fan also increases. As the vacuum becomes greater the indicator needle moves up the scale from the “Filter Is Clean” range into the “Change Filter” range. Instead of opening the air handler and checking the filter, you monitor the indicator needle on the gage. When the needle moves into the “Change Filter” range you know it is time to change the filter in your furnace or air conditioner.

Simple to use and set up

Once it is installed you calibrate it by installing a new filter and adjust the calibration screw on the face of the gage. Turn the screw in the down direction until the indicator needle is located in the centre of the “Filter Is Clean” position. When it moves into the red “Change Filter” zone you know it is time to replace your air filter.

This is a great way for you to monitor your air conditioner filter or furnace filter and get the most out of it. By monitoring the air pressure in the air handler you can accurately determine when filter performance is beginning to decline and know that it is time for it to be changed before equipment operating efficiency begins to decline.

You can learn more or order one at NordicPure

Don Munn About Don Munn
Don has been working in the HVAC industry for more than 25 years and shares his experience and knowledge on this site. If you find the information presented here helpful please use the buttons below and share with your friends.



Leave a Comment

Heads up! You are attempting to upload an invalid image. If saved, this image will not display with your comment.



In an effort to provide more helpful advice I have added an option for you to include an image with your comments. Since a picture is worth a thousand words it will enable me to better understand the problem you are trying to solve and serve you better.

Previous post:

Next post: