Furnaces are one of the most common, efficient and economic ways to heat your home or office space, and they work through the simple principle of heating air and pushing it into your home via the duct work (known as forced air furnace) or by filling radiators or baseboard tubes with very hot water and letting them distribute the heat (radiant system).
However, if you remember that heating and cooling amount to 40% of a household’s bills on average, you will see why it is important that your furnace not only heats well, but is also energy efficient and economically viable. If your furnace is underperforming, your electricity and gas bills will show it quickly.
The first thing you need to do is make sure you get the right furnace for the job. Let’s talk a bit about the types of furnaces and their characteristics.
Most furnaces rely on fossil fuels to operate, burning gas or oil to create the heated air that will then be distributed all over your house. Electric options are better for the environment, but they also have their plus and cons. Let’s go into more detail.
Gas furnaces are the most common and most efficient furnaces at the moment, feeding off municipal gas lines that provide fuel at a very competitive price. This gas is fed into a burner, where several jets feed the controlled flames that heat air, which is then circulated through the house.
They are cheap to run and very convenient, but if you are ecologically minded you might want to consider other options.
There are areas of the USA where natural gas is not readily available, and that’s where oil furnaces come in. However, if gas is available it is preferable, since oil is about 10% less efficient. We will discuss annual fuel utilization efficiency (AFUE) ratings later on.
In very loose terms, an oil furnace works like the combustion engine of a car: gas is sprayed into a combustion chamber and lit up by a spark, to heat water or air depending on the type of furnace.
The cleanest of these options, electric furnaces rely on heating elements to create the warm air that will circulate through your home. The furnace cost is lower than the previous options, and they also tend to be smaller in size, which can be very convenient.
While they are technically the most efficient of the three, since 100% of the energy is transformed into heat, the cost of electricity makes them a less attractive option compared to the gas furnace, which is less efficient yet much cheaper to run.
The purchase and installation of your furnace will be a serious investment, and they should be carefully considered. Installing a gas or oil furnace are jobs best left to professionals – kids, don’t try this at home! Furnaces have many different parts and systems: the gas or oil sources, electrical connections, ducting and plumbing. The consequences of a poor job could be very serious, if you consider that flammable gases, jets of fire and the potential of a winter with no heat are on the line. Shop around and find an HVAC contractor you can trust to carry out the installation of your furnace or your entire HVAC system.
Generally speaking, electric furnaces are the easiest to install, with the smaller ones working on a plug-and-play basis. However, any larger furnace will require a special heavy duty power outlet, an air intake, and a safe space clear from all flammable materials.
Gas furnaces will additionally require to be hooked to the gas lines, with all the considerations that entails. And oil furnaces have an oil tank that has to be properly stored with all safety precautions. Remember that whenever fuel is burning, carbon monoxide is created, so a good installation is crucial to prevent carbon monoxide leaks, which could affect your health and your family’s.
Nationwide average costs for installing a furnace range from $2500-6000, with an average of around $3000. Don’t skimp on installation costs: a contractor that underquotes may be tempted to cut short on testing time, for example, and leave you with a flawed installation that can spell disaster (or at least severe inconvenience) down the line.
Furnace installation costs will vary depending on the type of furnace you choose and whether or not you also require the installation of the ductwork and distribution system required to heat your house or building.
Heating and cooling are almost half of a household’s monthly expenses, and keeping them under control can make a real difference to your budget.
Let’s talk about annual fuel utilization efficiency (AFUE), one of the ways in which a furnace’s efficiency is calculated.
In the simplest possible terms, a furnace converts fuel into heat. The big question is, how well does it do its job – what percentage of the fuel is effectively turned into heat, and how much is lost? That, in a nutshell, is the meaning of a furnace’s AFUE rating.
If a furnace’s AFUE rating is 90%, it means that 90% of the fuel is converted into heat, while 10% is lost as exhaust. The ratings scale range from 30% to 100%, but if your rating is 30% you should get that furnace replaced ASAP – it is wasting twice as much fuel as it is using for heat!
On average, gas furnaces are more efficient than oil furnaces, and electrical furnaces are the most fuel efficient of all. Electrical furnaces have a 100% AFUE rating, which means they are 100 percent efficient at turning electricity into heat – no energy is wasted at all. Modern gas furnaces have AFUE ratings of 88-98% on average, while oil furnaces score a little lower with an average of 80-90% annual fuel utilization efficiency.
A furnace’s AFUE rating is a great place to start deciding if a given furnace is the right one for you, but it is not the only factor you should take into consideration. For example: if you are trying to save money in bills, electrical furnaces are not the best option – even though they have perfect efficiency, electricity is much more expensive than gas, so your bills would be higher with electricity (even if they are the most efficient furnaces) than with a slightly less efficient gas furnace.
There are several factors to keep in mind when choosing a high efficiency furnace – we already went over AFUE rating and type of fuel. Now let’s talk about sizing.
When designing any kind of HVAC system, or a heat system in particular, it is important to have a professional carry out the load calculations to make sure you get a furnace that emits the right amount of heat. This is measured in BTU (British thermal units), and if you’ve ever shopped for a furnace you will remember each option had a prominently displayed BTU/hour number, usually ranging between 10,000 and 150,000.
It is pretty obvious why you don’t want a too-small furnace: it will run too often, wear itself out sooner, and it may not even be enough to heat your home appropriately on especially cold days. A too-large furnace is also not recommended: if it heats too much or too quickly, the thermostat will make it shut down often to keep your home from being too warm. This is called “short cycle”, and is actually quite wasteful in terms of energy consumption, not to mention it will also shorten the lifespan of your furnace.
The right size furnace for the space you want to heat will ensure optimal efficiency and the longest life span. But how do you find out the right size?
While a proper load calculation is best left to the experts, there are many tools online that can help you get a ballpark number. These formulas take into account the area of your home, number of floors, location and insulation levels, and they will give you an approximation of how many BTU/hour your furnace has to be able to provide.
Old school furnaces had two settings for their blower: on and off. This is called a single stage furnace blower. When the temperature drops below the set threshold, the thermostat starts the blower, to heat up the house. When the air inside the house reaches the desired temperature, the thermostat turns the blower off. This is not very efficient, and results in uneven temperatures and an excessive use of energy.
Next generation furnaces came with multi-speed blowers, which have 2 blower settings instead of just “on”. This type of furnace is popular right now, and conveniently priced. Multi-speed blowers are the current industry standard, and they do partially solve the issue, but they are still not the most energy efficient.
The newest development (and by “newer” we mean it was developed in 1985) is the variable speed blower. Based on an electronically commutated motor (ECM), a variable speed blower keeps the air circulating continuously, so the rooms are always at the right temperature. Since it doesn’t have to stop and start, there is less wear and tear on the device, and greater fuel and energy efficiency. Variable speed blowers are quieter, require less maintenance and keep the air in the house fresher and cleaner. The downside? They are more expensive up-front, of course, but an investment worth considering if this is a place where you will live for a long time, or if you suffer from allergies or asthma.
They say “If it isn’t broken, don’t fix it”. But they should also say “if you give it maintenance it won’t break in the first place.” Yearly maintenance of a furnace is not expensive at all, and it will prevent costly repairs and the inconvenience of your HVAC system failing in the months when you need it most.
A standard maintenance and revision call should include most of these check boxes:
Oil and gas furnaces have a few additional steps, related to the fuel itself:
It is recommended that you have your furnace and entire heating system service at least once a year, ideally before the start of the cold months. An inexpensive maintenance visit may have a technician cleaning some vents and rewiring a connection or two – it doesn’t seem like a lot, but not doing it might result in a much bigger problem down the line. A clean, well maintained system performs optimally and uses as little energy as it ever will.
Heating your home will always amount to 40-60% of your household budget, and furnaces are not cheap to buy or install. Do your homework and consider your needs and options carefully before investing. For example – are you sure you need a furnace, or will a heat pump do the job? Are you ready to change to a more efficient furnace with higher AFUE rating, or are you planning to move in the near future? Are you sure you have the right size furnace in your home, or have your needs changed?
Our experts will be happy to help you answer these and any other questions you may have regarding the purchase, installation, maintenance and repair of your furnace or any other part of your HVAC system. Get in touch and let us help you save money while staying comfortable year round.