Repair or Replace Your Furnace or AC? How to Decide

Sooner or later every furnace and air conditioner reaches the point where the next repair raises a bigger question. Replacing too early wastes money on equipment that had years left; waiting too long means paying for repeated repairs, high energy bills, and the risk of a failure on the coldest or hottest day of the year. Working through the factors below makes the decision clearer before you sit down with a contractor.

Start with ENERGY STAR’s signs

ENERGY STAR lists several signs that it may be time to consider replacement:

Sign	What ENERGY STAR says
Heat pump or air conditioner more than 10 years old	Consider an ENERGY STAR model; installed correctly, high-efficiency units can save up to 20 percent on heating and cooling costs
Furnace or boiler more than 15 years old	ENERGY STAR furnaces are about 15 percent more efficient than conventional ones
Frequent repairs and rising energy bills	Equipment may have become less efficient
Some rooms too hot or too cold	Equipment operation, ducts or insulation could be the cause
Humidity problems	Poor operation, inadequate equipment or leaky ducts
Excessive dust	Leaky ducts pulling air from attics and crawlspaces
Noisy system	Undersized ducts or an indoor coil problem

None of these alone forces a replacement. Several together make a strong case.

Find the age

The manufacture date is usually encoded in the serial number on the unit’s data plate; manufacturers publish how to read it, and a technician can tell you during a visit. Write down the ages of both the indoor and outdoor equipment, since they are sometimes different.

Look at repair history and costs

Gather past invoices. A pattern of growing repairs on an aging system, or a single repair that is a large share of the cost of new equipment, points toward replacement. A minor repair, such as a capacitor or igniter, on a mid-life system that otherwise works well usually makes sense to fix.

Safety comes first

Some findings take the decision out of your hands. ENERGY STAR notes that a dirty burner or cracked heat exchanger causes improper burner operation and can make equipment operate less safely. A cracked heat exchanger in a gas furnace can allow combustion gases into the air stream, and most technicians will recommend replacement. Make sure the home has working carbon monoxide alarms while you decide.

Fix the house before sizing new equipment

Replacing equipment does not fix leaky ducts or a poorly insulated attic. ENERGY STAR estimates that in a typical house about 20 to 30 percent of the air moving through ducts is lost to leaks and poor connections. Sealing ducts and improving insulation can reduce the size of system you need and solve comfort problems a new unit alone would not. Ask contractors to perform a load calculation rather than matching the old unit’s size.

Get good quotes

• Ask for at least two written quotes with model numbers, efficiency ratings and warranty terms.
• Ask whether the quote includes duct inspection or sealing, thermostat changes, permits and removal of old equipment.
• ENERGY STAR publishes tips for hiring a heating and cooling contractor, and emphasizes quality installation, since even efficient equipment performs poorly if installed incorrectly.
• Check for utility rebates and tax incentives for efficient equipment in your area.

Matched systems

If you replace an outdoor air conditioner or heat pump, the indoor coil usually needs to be matched to it for rated efficiency and reliability. Replacing only half a split system can save money upfront but may cost more over time.

Common mistakes

• Replacing in an emergency without comparing options; plan ahead for systems near the end of life.
• Upsizing in hope of more comfort.
• Ignoring ducts and insulation.
• Choosing on price alone without checking installation quality.

When to call a technician

Call a licensed HVAC contractor for an evaluation whenever your system shows several of the signs above, needs a major repair, or has any safety finding. ENERGY STAR recommends annual check-ups in spring and fall; those visits are a good time to ask how many years the equipment likely has left and to plan replacement before it fails.