I have a 30 year old furnace that still works. Should I get a new one?

33 year old furnace

It’s estimated that 97% of Albertan households heat their homes with natural gas, most commonly with a forced air furnace. Knowing that you are getting the best bang for your buck in heating your house is important to almost everyone in the province. How do you know if you are getting the best deal with your old furnace?

Why do old furnaces last longer than newer ones?

One interesting part of the HVAC and plumbing industry is seeing mechanical systems built in different eras. From refurbished systems in Old Strathcona built in the 1910s, to the 60s era houses of Parkallen and the brand new developments of Windermere and Summerside, we see all sorts of different issues. We would like to address the special case of houses built in 70s and 80s.

Something that surprises many homeowners is that older inefficient furnaces are routinely expected to outlast modern furnaces by a factor of two. Primarily this comes down to the construction of the heat exchanger.

What is a heat exchanger, and what are they made of?

A heat exchanger is a group of metal coils in the airflow of the furnace that is designed to take the heat from the natural gas flame and transfers it to air being blown across it.

Older style furnaces were built with a heavy metal heat exchanger, using materials like cast iron. While these are extremely durable, they are also not particularly efficient.

Newer heat exchangers are made of stainless steel or aluminized steel. Higher efficiency is achieved with the higher thermal conductivity of the materials as well as modern fabrication which can make the walls of the exchanger much thinner. The tradeoff though is a lower lifespan for these high-efficiency heat exchangers.

It is quite common to see old furnaces last 30 or 40 years with proper maintenance. However, they are also quite inefficient, converting only about 60% of the energy used into heat for your home. In comparison, newer furnaces usually will only last 15-25 years with regular maintenance but will convert upwards of 90% of the energy into usable heat.

How much money can I save?

Many houses that we visit that were built between 1970 and 1990 still have their original 60% efficient furnace coming up on the end of its usable life. In many cases, we highly recommend swapping out your old low-efficiency furnace for a high-efficiency furnace for cost reasons alone.

To estimate the amount you spend on heating costs, have a look at your ATCO or Direct Energy natural gas bills from July and August. That should give you an idea of how much you spend on heating your hot water if you use a gas fired hot water tank or on demand heater (and assumes your AC and stove are electric). Extrapolate that over 12 months, subtract that and your delivery charges from your total annual bill, and that should give you an idea on your natural gas heating costs.

Then plug your total into the calculator below


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For example, if you are spending $1,000/year on your annual natural gas consumption, you can expect to save $348/year on your gas bill alone. Coupled with electrical savings with modern furnace fans and better overall efficiency from multistage or variable speed burners, you can save in excess of $500/year in many cases.

An average low-to-high efficiency furnace conversion with a mid-range modern furnace typically costs between $4,500-$6,000. Even if you would rather finance a new furnace with our easy-financing program, we find that in 2,000 square-foot+ homes, converting from a low-efficiency to a high-efficiency furnace lets you save more on your heating costs than your financing cost, with the added benefit of a more comfortable, quieter, more environmentally friendly furnace.

Do you need some advice about saving on your heating bill in the winter? Leave us a message at (587) 773-2612 and we will get back to you as soon as possible, or call (780) 231-0064 if you need to speak to someone immediately. To schedule an appointment, pick your preferred time on our online booking page.

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