How long do furnaces last? The average furnace probably works for about 14-20 years, assuming it is properly maintained. So by the time your furnace dies and you need to buy a new one, you are looking at replacing a mechanical and electronic appliance that is almost two decades old, which is an eternity in these modern times.
So let’s say you woke up this morning and your furnace is dead. Chances are, it was designed and installed back in the early 90s or late 80s. In those days, a good furnace had an efficiency rating of about 60-80%, meaning that 80% of the gas or oil burned went to heat your house, and the rest was lost as waste heat up your chimney or vent. So you go shopping for a new furnace today, and you see 90, 92, 94, even 95% efficiency measurements on these new furnaces. What does this mean? What should you research and buy?
How A Furnace Works.
As you research purchasing a new furnace, you should consider the following points:
- Gas Furnace. For a gas furnace, which most of the United States uses, your first choice will be the heat output of the furnace, measure in British Thermal Units, or BTUs. For a 1500 square foot home, a 60,000 BTU furnace is probably adequate.
- Measurement. Your Custom Air installer will measure your home and calculate the required size of furnace, or may simply replace the existing unit with one of the same size. If your furnace is too big for your house, it will run at full power and turn off long before it gets to an efficient heat and level, and you will be wasting money — so big is not always better.
- The next choice will be in efficiency ratings. Most older furnaces were only 80% or less efficient. Almost all modern furnaces are a minimum of 90% on the efficiency scale, and you will see them rated all the way up to 97%. When it comes to cost, you will find about a 10% differential between a 90% furnace and a 94-95% furnace. Over the years, this additional efficiency will pay for itself so consider buying what you can afford. So the efficiency rating tells you how well the furnace turns the fuel into heat for your home — how it does that is through its burner and heat exchanger; and the blower sends the warm air through the ductwork into your house.
- Blower. The final option is the blower, which is basically a fan that pushes all the hot air from the air handler, through the ductwork, and out through the vents in your house. Old blowers ran at a single speed. The newest blowers are variable speed, meaning they can run low, high, or anywhere in between, depending on what stage the furnace is in and how heat can most efficiently be sent into the home. These motors are very efficient and use less energy than a 100 watt light bulb, meaning you save money in gas and in electricity costs. Compared to the old-fashion blower, the variable speed blowers run more often and at lower speeds. This keeps the warm air circulating better in your home instead of piling up at your ceiling, away from where you are sitting. It also means your air moves through your filter more often, resulting in cleaner air.
New Furnace Installation
Installing a new furnace is not as simple as it appears. You’d think it could be done in an hour or two, but it can easily take 2 men a full 8 hour day to remove an old furnace and put in a new one, complete with venting, drainage, electrical hook up, gas hookup, etc.