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COLUMN: A few tips on furnace care

Annual maintenance of home heating appliances mostly applies to gas and oil forced air furnaces, so that’s what we’re going to talk about here. This maintenance varies from some simple tasks to some much more difficult ones. Mostly, though, bear with this. You’ll likely learn something.

First, since we’re discussing duct work systems, it remains a simple conclusion that in order for those systems to work properly, all the air openings should be fully open. That includes both supply and return grills and registers.

On a service call one early winter, I arrived at a home out in the country which had called with a complaint that: “It’s colder than usual in here.” And it was. This place gave new meaning to the word “hygiene.” A sow had farrowed her baby pigs on the return air grate in the floor, which meant that air couldn’t get back properly to the furnace.

Which brings us to air filters. There are several catalogues out there that I have seen which recommend that you purchase a small filter to place in the supply register openings. Don’t.

You’ve already got a filter in the return air half of your system. That’s enough. Adding more somewhere else just blocks up the air flow, making it even harder for air to get out those openings. All that resistance to air movement means your furnace is running hotter than usual, and wasting more energy.

Over the years I’ve received complaints about the house being “dustier than normal.” True, forced air heating systems move a lot of air around, sometimes as much as all the air in your house four times an hour. That doesn’t mean it has to be dusty.

Sometimes, over the years, enough built-up dust accumulates in the ductwork that no matter how much you filter the air that returns from your rooms, it picks up dust on the way back to your rooms. Call a duct cleaner. I remember when the new high efficiency gas furnaces first came out. One of the reasons they pushed more heat into your house was because they blew much harder. Those of us in the trades soon learned to check the ductwork before we turned these mini tornadoes on and blew all that “slow” dust out. There were some upset homeowners there at first, believe me.

Furnace filters come in all kinds and types. Most of us are familiar with the spun fiberglas air filters. They sell for a buck or so, and if they’re held up to the light, you can see through them.

That leads many people to believe they aren’t any good. There are a couple of reasons they’re much better than you think, if you replace them frequently.

First, those strands are coated with an adhesive, to which dust sticks. That’s why you shouldn’t vacuum them. After you do that, they’re just about worthless. Second, a weird static thing happens when air moves quickly across those man-made strands in the filter. It’s the same thing that happens when you slide across your car seat and touch something metal – an electrical charge builds up. That electro-static charge attracts dust particles, which then cling to the filter fibers. Dust particles don’t attract other dust particles: change the filter. Most dust is too small to even see. You can see it? Change the filter.

Here’s the final information you really need to know. Over and over, those of us in the heating trade are finding that people buy and install a one-inch pleated paper filter. So far, so good.

Then, since it cost nearly ten times as much as the spun fiberglas filter, they think it should last 10 times as long. Wait a minute, here! You bought it and thought it was a good deal because you thought it would stop 10 times as much dust, right? You are right. But, if it stops 10 times as much dust, that means it needs to be changed 10 times as often.  Right?

Maybe not 10 times as often, but close. In the heating trade, we see furnace after furnace with cracked heat exchangers because people put those pleated paper filters in and then don’t change them more often. If you cannot afford to clean your air, don’t buy these filters. And whatever you do, do not vacuum a pleated paper filter. That doesn’t help. Change it, don’t clean it.

You will never hear a service repair man say: “Uh-oh! You changed your air filter too often.”

The Prairie Spy by Alan "Lindy" Linda