How much does it cost to put central heat and air in an old house

Ah, the refreshing cool of central air in the scorching days of summer.  But if your current AC is failing to chill your home and you’re ready to invest in a new system, it’s important to know what kind of central air conditioning you need and how much installation costs.

Central air conditioning costs an average of $5,651 to install; the typical range runs from $3,800 for smaller systems to $7,500 for larger or upgraded systems, according to HomeAdvisor. But many factors significantly impact the price, including the type of unit you purchase, the unit’s size and energy efficiency and the layout/structure of your home. 

Types of air conditioning (AC) units

Before making a decision on installing air conditioning (AC), it’s important to understand the options for residences. Basically, all air conditioning boils down into two categories: individual units and central systems. The most common types and their installation costs, via HomeAdvisor, include:

  • Window unit: This single device operates from your window and has an average cost of $150 to $500, but cooling is usually limited to just one or two rooms.
  • Portable unit: If you live in a mild climate, you may only need AC for a few weeks of the year. In that case, a portable unit (which moves from room to room, like a space heater) may be your best option. Prices vary by brand, but expect something similar to a window unit.
  • Ductless split air conditioning system: This is a three-part system that includes an air handler, an indoor evaporator coil and an outdoor condenser and compressor unit. Split systems cost between $2,000 and $14,500.
  • Central air system: A packaged central air system contains all the same elements as a split system, but they’re bundled into one unit placed on your roof or the side of your home. The system runs between $3,900 and $7,500.

How much does central air conditioning cost?

If you decide to go with a central air system, many factors determine the overall cost. The size of your unit in particular is an important consideration.

By “size,” AC industry professionals don’t mean the air conditioner’s physical dimensions, but its power — that is, its cooling capacity. This capacity is generally referred to as BTUs, an acronym for British Thermal Unit. A BTU is a measure of the amount of energy needed to lower the temperature of a pound of water by a single degree. As part of this measurement system, 12,000 BTUs are called one ton. For instance, a 2.5-ton air conditioner would be equivalent to 30,000 BTUs.

These are the average air conditioning unit costs, including installation, by size, according to HomeAdvisor:

AC sizeAverage cost
1.5-ton $2,500–$4,500
2-ton $3,100–$5,100
3-ton $3,400–$5,400
4-ton $4,200–$6,200
14 SEER $3,000–$6,000
16 SEER $3,700–$9,000

In general, for every 500 or 600 square feet of space in your home you will need about one ton of cooling. Older homes with outdated frameworks may not be equipped to support modern systems, so you could need extensive repairs or even replacement ductwork costing $10,000 or more.

What affects the cost of installing central air conditioning?

A variety of factors can impact the final price you pay for the installation of central air conditioning including the amount of ductwork involved and the fees for labor. Here are some of the installation costs to consider.

Pre-installation evaluation

Every air conditioning installation project is unique and will be based on the needs and condition of your house. Before a unit can be installed, it’s important to have a heating, ventilation and air conditioning (HVAC) professional assess your home. A pre-installation evaluation can determine such things as what size system you need, how well your home is insulated and whether there are existing ducts and vents. Specifically, the pro will perform a Manual J load calculation to measure how your home retains heat. This determines what size unit you’ll need, which will in turn influence the cost.

“The pre-installation evaluation is likely the most important step you undertake,” says Thomas Jepsen, founder of Passion Plans, an online platform that sells house plans. “While it typically costs about $250 for such an evaluation, it will save you thousands over the years. The pre-installation evaluation makes sure that you get the right air conditioning unit for your home installed.”

In fact, $250 may be on the less-expensive end of the spectrum. Bailey Carson, home expert with Angi, says the cost averages around $420 but can be as high as $2,000 depending on the size of your home and whether you’re looking for a simple or advanced audit.

Bear in mind that a pre-installation evaluation can help you avoid unforeseen setbacks that could drive up the overall cost of the work being done.

“Like with any project, planning is the most important thing you can do to limit unexpected costs, roadblocks or surprises down the road,” says David Steckel, home expert at Thumbtack. “With AC units in particular, a site visit to create a scope of work by a professional is required as they will base their calculations on the size and length of ductwork, the size of home and, of course, what problems you are solving for.”

Ductwork

Ducts and vents provide a flow system for the air conditioning. Older homes may not have ductwork in place, so depending on the type of air conditioning system you want to install, you may need to factor that into your costs, Carson says.

“There are ductless air conditioning systems, which tend to be both more efficient and more expensive than the alternative and are a good option if your walls are too thin for ducts,” Carson says.

Ductless units are typically wall mounted, and you’ll need a few to cool a home. Ducted units come in two forms: traditional larger-format duct systems and small duct high velocity (SDHV) systems, which use small, flexible tubing rather than standard ductwork.

“The age and wall assembly of your home will determine which system you go with,” Steckel says. “Central air conditioning became popular in the 1970s, so if your home hasn’t been renovated since before then, chances are you’re going to need to go with a SDHV system. If your home is newer than that, you probably can see the ducting system in your basement already.”

The cost to install ducts and vents can range from $500 to $2,100.

Labor

Central air systems do require a pro to install, and that means labor costs will be a significant part of the overall expense. The average cost for labor and installation of a central air conditioning system can vary significantly based on the size, shape and orientation of your home, as well as the contractor, Carson says. Another factor that impacts the labor cost: the energy efficiency of your unit.

An air conditioning unit’s seasonal energy efficiency is described as its SEER rating. SEER ratings are calculated by dividing a unit’s cooling output for a particular season by its electric input — or  usage — during the same season.

Air conditioning systems with higher SEER ratings offer operate more efficiently, but are typically more expensive to install. However, they may save you money in the long run through lower energy bills.

How to lower central air conditioning installation costs

Here are a few options to help bring down the cost of your central air conditioning project.

Shop around

To help minimize the price to install central air, shop around to see which provider and system fit your home and your budget. Many companies may manufacture the size air conditioning system you need, but costs vary greatly. HomeAdvisor found Payne to be the least expensive central air manufacturer based on average pricing of $1,400, but Aire-Flo, Coleman, Comfortmaker, Tempstar and Whirlpool all priced below $2,000 as well.

Install in the off-season

If possible, plan to install your unit during spring or fall — before the rush starts.

Research rebates

The popular $300 federal income tax credit for homeowners who installed Energy Star-rated central air conditioning expired in 2021, alas. But you can research the availability of state and local credits for energy-efficient units. Some utility companies and manufacturers offer rebates too, especially if you install in the off-months before summer heat kicks in.

Buy a smaller unit

Residential central air units are available with up to 5-ton capacity, but if you live alone or only need to cool certain areas, you could benefit from a smaller system. It is also possible that you don’t need a new AC unit but just some simple repairs to fix leaks or replace parts.

How to pay for central air installation costs

A central air installation can be a four- or even five-figure significant investment, and not everyone has thousands of dollars at their disposal. Here are some financing options.

Personal loan

A personal loan is an excellent option if you need to receive funds quickly for home improvements. There are almost no stipulations regarding its use, and loans can exceed $35,000 if you have good credit. Personal loans give you a fixed amount that is distributed in a lump sum. There is no need to use your property as collateral, but you’ll likely pay higher interest on this type of unsecured loan. Terms for personal loans typically range from 12 months to 60 months, and the loans have fixed monthly payments.

Home equity loan

A home equity loan is a popular way to finance a new central air unit using the equity you have in your home. This is also referred to as a second mortgage and is often used for large expenditures, such as installing a new central air system. As with a personal loan, you receive the funds in one lump sum and make monthly payments with interest until the loan is repaid. Home equity loans usually have lower interest rates than personal loans since they are secured by your home. Terms may extend up to 10 or 15 years.

Home equity line of credit

A home equity line of credit, or HELOC, also uses your home as collateral, but it works more like a credit card. Your bank gives you a credit limit that can be continually reused within the draw period as long as you make your payments on time. This draw period lasts around 10 years. After that, you’ll make payments on the amount you borrowed for another 10 to 20 years. HELOCs charge a variable interest rate, which means that your payments will fluctuate based on how much you borrow and the current market rate you’re being charged at the time of payment.

The bottom line

There’s no doubt that installing central air can be pricey. AC unit costs can climb to $9,000 or more, especially if you have a large or old home. If that price is daunting and you don’t have the funds to pay out of pocket, there are ways to finance the expense. If you’re looking to borrow money to install central air, compare rates from a few personal loan, home equity loan and HELOC lenders to see what your monthly payments might look like.

Frequently asked questions

How much does it cost to replace a central air unit?

According to HomeAdvisor, it can cost as much as $12,500 to replace an AC unit. The work required to remove and dispose of the old system adds to the price, as well as the size of your home, the brand of the AC unit and the ductwork complexity.

If I already have ductwork installed, can it be used with a new unit?

While ductwork can fail over time, replacing ductwork isn’t always necessary. If there’s a problem with airflow in your house, ducts can be repaired, reattached or resealed individually. Dust and other impurities can also be cleaned out of old ductwork to improve airflow efficiency.

Can I install my own central air unit to save on costs?

A DIY approach may seem cost-effective, but it may be a better idea to leave it to the professionals.

Depending on where you live, you may need a permit to install a new unit. A professional in your area already knows the ins and outs of this process. Adding refrigerant to your AC unit or removing an old unit that has refrigerant inside may also require an EPA certification. To obtain this sort of certification, you must pass an exam and pay a fee, whereas a technician is already certified.

You could also end up paying more over the long run by installing the system yourself. If ductwork is not properly sealed and insulated, it greatly reduces your systems efficiency and you could see massive spikes in your energy bills.

Installing the system yourself may also void the warranty, as most require units to be installed by licensed technicians.

How long do AC units last?

AC units can last up to 15 years, according to HomeAdvisor. However, if a unit’s frequently used or not maintained, it could require replacement much sooner. Units should also be replaced once they’re out of date or not working properly.

Learn more:

  • 10 ways to save on air conditioning costs
  • 6 ways to pay for home improvements
  • Should I get a personal loan for home improvements?