Frequently asked questions
How long does furnace installation take?
A straightforward replacement often takes one day. Changing from 80% to 95%+ efficiency, new venting, duct modifications, or moving the furnace can add a day or more.
How long do furnaces last?
Gas furnaces commonly last about 15–20 years, sometimes longer with good maintenance. Age alone isn't a reason to replace, but it matters when a major repair comes up.
What size furnace do I need?
It depends on your home's heat loss, not just square footage. Installers should use a Manual J load calculation, which accounts for insulation, windows, air leakage and your local design temperature.
Is a 95% AFUE furnace worth it?
In cold climates with long heating seasons it usually pays back faster. In mild climates the savings are smaller, and the venting cost may tip the balance toward 80%.
Do I need a permit to replace a furnace?
Most US jurisdictions require a mechanical permit, and often a gas permit, for furnace replacement. A licensed installer typically pulls the permit. Requirements vary by city and county.
Are there tax credits for a new furnace?
The federal 25C energy-efficiency tax credit ended for equipment placed in service after December 31, 2025. Check your utility and state energy office for current rebates.
Should I replace my AC at the same time?
If the AC is older and uses R-22 refrigerant, or the coil is incompatible with the new furnace, replacing both together can save labor and improve matching. If the AC is newer, it can often stay.
Can I install a furnace in winter?
Yes. Installers replace furnaces all winter. Many providers can supply temporary heat if the old furnace has failed.
Do you cover my area?
The installer network covers all 50 states and DC. Find your state on the coverage map.
Who installs the furnace?
An independent, licensed HVAC installer. Keystone Comfort is a referral service. See how it works.