There’s a phrase used by a few people in the plumbing and HVAC industry: “It’s an oldie but a goodie.”

You may have heard the phrase used a time or two. It’s used to describe appliances that are outdated but miraculously still work.

The problem is, when it comes to your heating system — or just about any system in your home — it couldn’t be further from the truth. Your furnace may be 20 or 30 years old, but just because it still works doesn’t mean it’s any good.

As your furnace ages, its efficiency declines. A couple of decades ago, it may have been running at 80 percent efficiency, but today, if it’s still the same furnace, it’s probably not reaching 50 percent efficiency, even on its best days.

The truth is, while it’s tempting to keep major appliances until they simply stop working, that long-term cost is much higher than it would be if you had replaced the appliance sooner.

For instance, it’s cheaper to replace an old furnace now than it will be five years from now. Consider the associated costs. The price of parts will be higher, the price of labour will be higher, and the price of natural gas will be higher. The prices on parts and labour may only go up incrementally, but when you factor in efficiency, that’s when costs really go up.

The challenge of the “oldie but a goodie” line of thinking is that you have no real way of knowing when an oldie is going to fail. When you are constantly using an old furnace in the winter months, you’re asking a lot of the system. It could be Christmas Eve, Christmas Day, Boxing Day — you name it. It’s when you have people over and you want a warm home. It happens. I know because I’ve gotten the call for help.

As we head into the cold months, one of the most important pieces of advice I can give anyone with a furnace is this: If you have an older furnace, take care of it now. Take care of it before you have a problem so it won’t leave you in the lurch when you need it most. Costs will be more manageable — and you may even be able to take advantage of a few rebates.

Now, I also have advice for anyone with a newer furnace. When you bought your new furnace, this year or in the last few years, you got a much more efficient piece of equipment. Naturally, you want to keep it in good shape. All you need to do is make sure it’s getting checked out once year. A yearly inspection means problems are found early and your system maintains a higher level of efficiency for much longer.

I don’t want you to get caught off guard this winter. If history tells us anything, you’re going to need your furnace this year. Over the past 20 years, if we had a hot summer here in the Lower Mainland, a cold winter followed. When we had a mediocre summer, a mediocre winter followed. Well, if this summer is any indication, we’re in store for one cold winter. Are you ready?