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Why Do I Need To Replace My Air Conditioner and Furnace at the Same Time?

September 6th, 2013

We can all agree that replacing an air conditioner and a furnace at the same time is expensive.

But replacing them both at the same time (even if the furnace is still working) will actually save you more money in the long run.

Not only that, but it will also save you from the frustration of getting a new air conditioner that won’t work as efficiently as you’re expecting.

In this article, we’ll explain why replacing your air conditioner and furnace at the same time (in order to install a “matched” system”) is both smart and cost effective.

Why your furnace and air conditioner are like conjoined twins

In a sense, your air conditioner and furnace are like conjoined twins– separate beings that are combined together and share the same “system.”

You see, there is a certain kind of conjoined twins that share a liver and intestines. So separating them can be tricky and cause problems.

The same could be said with separating your air conditioner from your furnace because they are “conjoined at the hip” since they share the same air handler/blower.

Let’s expand on the “conjoined” aspect for a moment by looking at your air conditioner as a whole.

A split air conditioner is composed of two main units:

  • Outdoor cabinet, containing condenser coil (1) and compressor (2)
  • Indoor cabinet, containing the evaporator coil (3) and air handler/blower (4)

Because your indoor unit and furnace share the same air handler/blower, you can’t separate them. You must replace the furnace to also replace the inside air conditioner unit.

So if you say you want to replace your air conditioner but not the furnace, that means you can only replace the outdoor unit while leaving the indoor unit in place.

Doing this creates some costly problems.

Problems with a mismatched system

Decreased lifespan– According to the Air Conditioning, Heating and Refrigeration Institute (AHRI), “When improperly matched, the efficiency and longevity of these systems are significantly compromised.”

Lower efficiency– Imagine putting a donkey and a horse on the same yoke to pull a wagon. The horse wants to speed ahead while the donkey slowly lags behind, causing the cart to slow down. That’s what it’s like to have a new energy efficient outdoor unit but still have an old inefficient inside unit. Even if your new outdoor unit is 18 SEER, the old unit (probably an 8-10 SEER unit) causes the system to lag behind, keeping your energy bills just as high as they were before.

Premature breakdowns– Mismatch units create undue stress on your air conditioner, resulting in an unnecessary, premature breakdown.

Possibility of no warranty– Many manufacturers know the problems associated with mismatched systems, so they often won’t offer a warranty for a condenser coil (outside unit) only replacement.

Minimize installation costs
You also need to think about how much you’ll pay on installation, which strongly affects how much you pay for a new system.

So replacing the outside unit, waiting a few years, and then having another contractor come out to install the furnace and inside air conditioner unit can be pricy.

Therefore, replacing the furnace and air conditioner at the same time will help minimize installation costs.

Get free estimates
In the end, the decision is yours and we’ll support whichever you decide to go with. But we do strongly suggest getting a matched system to maximize your system’s efficiency, reduce your energy bills and extend the life of your new system.

To see how much it would cost to just replace just the air conditioner vs. replacing the entire heating and cooling system, contact Service Champions to get free estimates.


Service Champions - East Bay
7020 Commerce Dr
Pleasanton, CA 94588

(925) 444-4444
(925) 598-1827 - Fax


Service Champions - Sacramento
4430 Yankee Hill Rd
Rocklin, CA 95677

(916) 777-4444
(916) 415-0687 - Fax

San Jose

Service Champions - San Jose
1735 Angela St
San Jose, CA 95125

(408) 777-9444


Service Champions - Concord
200 Mason Cir, Suite 200
Concord, CA 94520

(925) 444-4444


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