In our part of the world, most houses have gas heat. I’ve got two gas furnaces myself, one in the basement and one in the attic. Each one is 14 years old, which is old for a gas furnace. (Hint: Just about any gizmo with a motor in it lasts about as long as a dog. After about 12 to 15 years, it’s likely to be wheezing and creaking, and it could go at any time.)
If you want to know how old your furnace is, find the data plate. It’s a sticker or a metal plate, usually inside the furnace, behind the removable front cover. Pay attention to the numbers at the beginning and end of the serial number. Most of the time, you’ll find two numbers together that tell the year the furnace was built. For instance, the serial numbers on my furnaces contain the combination 85. That’s because my furnaces were built in 1985.
Furnaces, like dogs, take some care and feeding. If you just ignore them, they will die prematurely. If you haven’t done it already, now’s the time to get your furnace cleaned and serviced.
Two things I know from looking into the bowels of gas furnaces five days a week:
1. A whole lot of people never get their gas furnaces cleaned and serviced.
2. A whole lot of heat-and-air contractors do a sorry job of cleaning and servicing gas furnaces.
Let’s start with number one. You furnace owners, listen to me: You need to get your heat-and-air system serviced twice a year. Once in the spring, before it gets really hot, and once in the fall, before it gets really cold. Little known fact: Failing to get your A/C system serviced can kill your furnace. When the A/C system runs, it produces water, which can leak into your furnace and turn it into a rusty mess. A springtime service call should prevent that.
Just about every day, I see a gas furnace that’s all rusty inside. Rust is a natural thing, of course. Given enough time, just about all gas furnaces will rust out. But regular fall servicing can keep rust and crud from building up to the point where they make the furnace useless.
Now, on to number two: It’s not at all rare for me to find a furnace that has about a gallon jug’s worth of rust in it. Along with the rust, I’ll often find about a dozen matcheswhich were used to light the pilot lightinside the furnace. Mixed in amongst that mess, I’ll see the dried-out carcasses of a few humpback crickets and brown recluse spiders, along with the furnace’s original (scorched) owner’s manual.
Of course, I report this stuff to my customers (the homebuyers) who promptly tell the furnace owners (the homesellers) that I said the furnace needs to be cleaned and serviced. Often as not, the owner swears up and down that he just paid somebody good money to clean that furnace. About half the time, the owner has a receipt to prove it. I can only conclude that some heat-and-air contractors are just plain cheating people; or, somebody is sneaking into houses that are for sale, and dumping a bucketful of rust, bug bodies, matches, and paperwork into the furnaces.
I know that the guys who service my heat-and-air equipment are doing a good job. I know it because I watch ’em. When they’re done, I check behind ’em.
It’s not hard to pop the cover off a furnace and look inside. Anybody can tell the difference between clean and dirty. After all these years, I’m ashamed that I still check up on my service people. But I can’t help myself. My everyday work has made me a little paranoid.
While you’re checking up on your heat-and-air guys, see if your gas furnace is vented up an old masonry chimney. Here’s how: Find the furnace flue (the hot metal pipe, which you don’t really want to touch) and follow it to where it disappears. If it goes into an old brick or stone chimney, that could be a problem. It’s a common problem in houses that are more than about 20 years old.
If the furnace flue goes up an old chimneyand if that chimney isn’t lined, and if that chimney doesn’t have a cap on top to keep out rain and birds and leaves and berrieschances are good that the chimney is full of crud. If the chimney is full of crud, toxic combustion products, such as carbon monoxide, could be spilling into your house. Even if the chimney is clear, there’s a fair chance that water vapor from the furnace is destroying the chimney from the inside.
If your furnace is vented up an old masonry chimney, get a chimney sweep to check the chimney. Chances are, the chimney will need cleaning. If there’s no rain cap or screen on the chimney, it’ll need one of those. If the chimney is deteriorated, or if the flue is the wrong size or shape for your furnace, the chimney may need to be lined.