Is your furnace filter clogged? Monitor it: the instructions on my expensive furnace filter say to change it every 90 days, but it still looks dean. I hate to waste money by replacing a clean filter, but I don't want to damage my furnace. Is there a test I can do?
If you read the fine print on your filter instructions, you'll notice that it rec ommends changing the filter at least once every 90 days, not every 90 days. Why 90 days? Nobody knows.
Keep in mind that the only time your furnace is filtering air is when the fan is running. That may be quite often in the dead of winter (or the height of air conditioning season). But the rest of the time your fan runs for only a few minutes every hour. So replacing it every 90 days, especially in the spring and fall, makes no sense whatsoever.
To track the real condition of your furnace filter, install an air filter gauge. We found a reasonably priced air filter gauge (GeneralAire G99 gauge; $16) from iaqsource.com (866764-9900). Install it either on the blower door or in the sheet metal after the filter slot (photo below). Once you calibrate it, the gauge measures pressure drop caused by a clogged filter. Check the gauge monthly. When the needle falls into the red zone, it's time to change the filter.
You can buy a remote installation kit for $6.50 (or make one yourself with three screws and a 10-ft. section of 3/8-in. o.d. vinyl hose). Then yon can mount the gauge on a wall outside the furnace room up to 10 ft. away for easier monitoring.
1 Drill a 3/8-in. hole in the blower door (check for any obstructions behind the door before drilling) and mount the gauge. Or, drill a hole in the sheet metal return duct (after the filter) and mount the gauge with the remote kit.
2 Install a new fitter and turn the blower fan on manually at the thermostat. Use a fiat-blade screwdriver to calibrate the gauge. Then turn off the fan and monitor the gauge monthly.
by Rick Muscoplat
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|Publication:||The Family Handyman|
|Article Type:||Brief article|
|Date:||Nov 1, 2009|
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