Are you trying to stay warm this winter but an extra sweater isn’t helping? When you’re cold and you look at the thermostat only to see it’s dropped really low, you know there must be a problem with the furnace.
Yet it can all sound like techno-babble when the repair technician is explaining the problem to you. If you want to know a little more about how furnaces work, then you’ve come to the right place.
Take a look below for a basic explanation of how a furnace gets the job done. We’ll also address some tips for choosing a new furnace, if you’re in the position of buying a new unit.
Inside the combustion chamber, the furnace’s pilot light starts the burner. That heats up the heat exchanger, where it has to reach a certain temperature before it can blow out into your home. The heat exchanger looks like a zig-zag shaped tube; inside it is where the action happens.
After the air is warm enough, it’s forced out through the plenum, the big box that connects the furnace to the ducts. Then it travels through the ductwork and into the rest of the house.
A typical furnace lasts about 20 years. Some last longer, with a few minor repairs, others don’t quite reach 20 years. Often a furnace repair is cheaper than buying a whole new furnace, especially if there’s a problem with the ignitor or thermostat problem.
Once the heat exchanger goes out, then it’s very expensive to fix a furnace. At that point, it’s usually time to buy a new furnace.
Buying a New Furnace
When the furnace goes out in the middle of winter, you’ll probably be more willing to pay for a really good furnace. A list of this year’s best furnaces can help you decide. Yet knowing about the different types of furnaces can also help you make a decision.
Your old furnace was probably a single-stage furnace. That means when it starts to blow hot air, it blows at full-strength. It’s either on or off, without an in-between setting. A new single-stage furnace is about 80% efficient.
More modern furnaces come in other types. For example, a two-stage furnace runs at about 2/3 capacity to heat the house, unless it’s very cold and it can’t keep the house warm at that level. Then it will blow at full-strength, or 100% capacity, to make sure you get to the desired temperature.
Two-stage furnaces are more efficient because they won’t always have to run as hard as they can. They save energy by running at a lower capacity when it makes sense. They are about 90% efficient.
You’ve probably guessed what the last type of furnace is: multi-stage furnaces run at different settings to accommodate all weathers and outside temps. These are between 96% and 98% efficient because they adjust their capacity up or down to suit your needs. The lowest setting is about 35% capacity, and the longer they can run at that level means they save more energy and save you money.
Budgeting for a Furnace
When you’re looking at buying a new furnace, the new furnace cost can give you a bit of sticker shock. Depending on the model and type of furnace you look at, the cost can be anywhere from $3500 to $7000 or more to buy and install the unit. Sometimes HVAC companies will run deals or you can check to see if the manufacturer offers a rebate.
Often the installation company will have different payment plans for their customers. Ask about the different options before you decide on a unit. If the monthly price is one you can fit into your budget, it may be worth it to opt for a more expensive model.
You should also ask about any warranties that come with the furnaces. Some companies include an annual service for the first few years, or the manufacturer offers a warranty on their unit for a number of years.
Be sure to take into account the higher efficiency of a new furnace and how much it will save you every month on heating bills. With multi-stage furnaces, you can expect to notice a big difference in your bill after using a 20-year-old furnace to heat your home.
Each furnace you look at should have an efficiency rating you can look at. Keep in mind the efficiency of the different stages discussed above, and that will help you know what to expect in an efficiency rating.
Commercial ironworks facilities and smelting workshops use furnaces to heat and melt the iron or tin. Yet these types of furnaces are different than the furnaces that heat your home. In your home, the carbon monoxide that’s a byproduct of the heating process naturally flows out through a flue, or a pipe that vents the gas out of the home.
When a heat exchanger breaks, it’s usually because the zig-zag pipe cracks, which means the carbon monoxide leaks into the home through the air ducts. Residential furnaces that vent the carbon monoxide to the outside are called air furnaces, and we say they are naturally aspirated.
Commercial furnaces, however, use the carbon monoxide in their chemical processes.
The blast furnaces used in a metallurgical workshop allow the carbon monoxide gases to flow up through the furnace. The metal products flow down through the furnace, and the result is a chemical reaction that helps achieve the end results. Blast furnaces blow, or blast, oxygen-rich air into the bottom of the furnace as part of the process, giving them their name.
The carbon monoxide still gets released, just not through a flue. It’s released when it reaches the top of the furnace after it’s had a chance to assist in the molten metal process.
Knowing how a furnace works can help you make the right decision when yours goes out. Whether it can be repaired for an affordable price or you’re better off replacing it, you’ll know what the repair technician is talking about when they explain the problem.
You’ll also be able to choose the right furnace for your home, now that you understand how they work.
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