Should I replace my furnace and AC at the same time?
Often yes, especially if your furnace is over 15 years old: ENERGY STAR says the only way to ensure a new air conditioner performs at its rated efficiency is to replace the heating system at the same time.
Why the two are tied together
ENERGY STAR explains that a central air conditioner needs a blower motor, which is usually part of the furnace, to move cool air through the ducts. If you connect a new AC to an older furnace and blower motor, it says the system will not perform to its rated efficiency.
Lennox makes a similar case for matched systems. It says hot and cold spots, noisy startups, and poor indoor air quality can result from mismatched units, and that matched system efficiency levels are higher than mixed-age systems. Lennox is a manufacturer, so weigh that as a sales perspective.
When replacing both makes sense
- Your furnace is over 15 years old, which ENERGY STAR specifically calls out.
- Both units have similar wear. Lennox says units of the same age have taken the same wear and tear, so they tend to need replacement together.
- You want one warranty. Lennox says a new warranty covers the entire system when both units are replaced together.
When replacing only one may be worth pricing
Lennox says a new outdoor unit alone can save energy, but the savings will not match a full matched system. If your furnace is much newer, ask the contractor what pairing it with a new AC means for rated efficiency and warranty, and have both options quoted side by side.
Check the ducts and the sizing either way
ENERGY STAR says sealing and insulating ducts can improve heating and cooling efficiency by as much as 20 percent, and that improper installation can reduce efficiency by up to 30 percent. Ask for a load calculation so both pieces are sized for your house, not copied from the old equipment.
Get both options priced
Ask for one quote that replaces both and one that replaces only the unit that failed. You can get a free quote through this site.
If only one system failed, start with HVAC repair in Omaha.
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Common questions
Can I replace just the AC?
You can, but ENERGY STAR says a new AC connected to an older furnace and blower motor will not perform to its rated efficiency, and Lennox says savings will not match a full matched system.
What if only my furnace failed?
Ask the contractor to quote the furnace alone and the furnace plus AC. If your AC is old too, Lennox notes that units of the same age have taken the same wear and tear.
Will replacing both reduce my energy bills?
ENERGY STAR and Lennox both say matched, efficient equipment performs better, but your actual savings depend on your house, ducts, and installation.