Should I Replace My 20 Year Old 10-12 SEER AC Unit?

Many homes stay cool and comfortable due to the hard work put in by AC units that are nearly 20 years old or more. While these units can still generally get the job done, they’re nowhere near as efficient as modern units.

If you have an older HVAC unit, you may be wondering if you should replace it, even though it still works.

This article is here to answer that very question and help you decide if a new AC unit is an investment worthwhile in your home, so continue reading to learn more!

SEER Rating of 20 Year Old Air Conditioner

The old HVAC system in your home may be nearly 20 years old. And while your 20-year-old air conditioner may still run, it’s not nearly as efficient as newer AC units on the market today.

Seasonal Energy Efficiency Ratio (SEER) ratings tell you your HVAC system’s energy efficiency. It measures this by using the cooling output for a regular cooling season and dividing it by the total electric energy input during that same season (i.e. the warm months of the year).

The result represents the unit’s energy efficiency compared to its cooling output.

For example, let’s say you have an old air conditioner system that you had installed in the ’90s, and its rating is 8 SEER. This essentially means that the unit’s maximum efficiency is 8 SEER, which is very low by today’s standards.

New AC vs. Old AC Efficiency

AC units built in the ’90s, with ratings as low as 8 SEER, are considerably more inefficient than modern units, which boast ratings up to 28 SEER.

Do Older AC Units Use More Electricity

Older AC units use more electricity than their newer counterparts. The cost savings are impressive, even between an older unit with decent ratings and a new unit with mid-range ratings.

The HVAC industry has progressed exponentially since the 90s. While the ratings of older units seemed excellent at the time, they appear sluggish and uneconomical compared to modern units.

Consider the examples below, where we put various SEER ratings against each other to help you understand the difference in efficacy.

SEER RatingAC Electricity Yearly CostCost Savings
8 SEER$1,6540%
9 SEER$1,47011%
10 SEER$1,32320%
11 SEER$1,20327%
12 SEER$1,10333%
13 SEER$1,01838%
14 SEER$94543%
15 SEER$88247%
16 SEER$82750%

3-ton AC.  3,288 yearly cooling hours.  11.18 cents per kWh.

10 seer vs. 14 seer

When minimum SEER ratings became an official mandatory rule for AC units in 1992, HVAC companies could produce units with ratings as low as 10 SEER.

For example, let’s compare a 10 SEER unit versus a 14 SEER unit.

What does 10 SEER mean? It points to the unit’s efficiency, which in this case, its maximum efficiency is 10 SEER. What does 14 SEER mean? It is the same concept, except it has a maximum efficiency of 14 SEER.

For ease of comparison, we’ll compare a 3-ton unit that runs for 3,288 cooling hours annually, at 11.18 cents per kilowatt-hour.

SEER RatingAC Electricity Yearly CostCost Savings
10 SEER$1,3230%
14 SEER$94529%

3-ton AC.  3,288 yearly cooling hours.  11.18 cents per kWh.

A 10 SEER unit costs about $1,323 to run for the given period. Compared to the 8 SEER models, which cost $1,654 annually to run, there is a 20% cost savings.

Now, consider the 14 SEER model, which costs $945 annually. This model saves 43% more than the 8 SEER model and saves 29% compared to the 10 SEER model.

12 seer vs. 16 seer

On the other hand, let’s look at two more efficient models: 12 SEER and 16 SEER. What does 12 SEER mean? This means the model has a top energy efficiency of 12 SEER. What does 16 SEER mean? Again, this model tops out at maximum energy efficiency of 16 SEER.

SEER RatingAC Electricity Yearly CostCost Savings
12 SEER$11030%
16 SEER$82725%

3-ton AC.  3,288 yearly cooling hours.  11.18 cents per kWh.

A 12 SEER model costs about $1103 to run in the same time frame. This is a 33% savings from an 8 SEER unit running cost. Or, climbing even higher up the ladder of ratings, a 16 SEER model costs around $827 annually, which is a 50% savings from the 8 SEER model.

The 16 SEER model costs roughly 25% less to run than the 12 SEER model. While saving a few hundred dollars in a year may not seem like much to some, it adds up over time.

Should I Replace My 20 Year Old HVAC?

Several components go into answering this question. Firstly, a new HVAC system is a significant investment. With installation, which we recommend, a new system can cost anywhere from $3,000 to $13,000.

The AC unit itself may only cost a few thousand, but the installation usually tacks on a considerable amount.

If you have existing ductwork in good shape, the installation costs may be lower. Nevertheless, investing in a new HVAC system is a significant undertaking.

Considering your HVAC system is 20 years old, the efficiency ratings are likely somewhere between 8 and 13 SEER. You could cut back on running costs by investing in a newer, more efficient model. Over time, with lower running costs, the unit will essentially pay for itself.

For example, let’s say you have an 8 SEER air conditioner:

You decide to purchase a 16 SEER unit, which is mid-level in the current rating range. You’d save 50% on your running costs annually. Let’s say the new system, complete with installation, costs $5,000.

If you’re cutting back on $400 per year in energy costs, the system will pay for itself in about 12 years. If you were to invest in an even more efficient unit, perhaps in the 20-28 SEER range, the savings would be even more dramatic.

Let’s elaborate on our last comment with another example: let’s say you have a 10 SEER unit and you want to replace it with a 25 SEER unit. You’d see very similar results, as you’d save about 58% in electricity costs simply by upgradings to the more efficient model.

However, it’s important to note that higher efficiency units are usually more costly than their less efficient counterparts. Either way, if you purchase a newer, more efficient model, you’ll definitely cut back on energy costs.

Older systems generally require more upkeep as they age, so you may also cut back on service visits that cost hundreds of dollars for repairs, parts, and labor.

Additionally, older units tend to be much noisier than newer models. Technology advancements, such as improvements in compressor technology and a new fan-blade shape, allow modern units to operate at around the same sound level as a conversation produces.

Or, in other terms, new models tend to operate at 1/20th of the noise level generated by older AC compressors.

Is It Worth It?

To answer the question: we think it is 100% worth it to replace your 20-year-old HVAC system with a newer, more efficient model. However, the decision ultimately falls to you. While you could save hundreds of dollars per year on running costs, a new system can be expensive.

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