Furnace Installation in Joliet, IL
A new furnace here will run from October through May every year. Tell us about the house, and a licensed contractor who covers Will County will get in touch.
Tell us about the job
It takes about a minute.
Eight months of heat, and winter nights near 20 degrees
Joliet homes run the furnace from October through May. That's eight months of the year, and on winter nights that average 20°F, it runs hard through most of them. A furnace going in here has to hold up to that stretch, not just a few cold snaps.
Most homes in the area heat with gas, and any new non-weatherized gas furnace has to reach at least 80.0 percent AFUE under federal rules. That's the floor to build from. Will County has also logged 17 winter storms and 202 damaging wind events over the past ten years, and in Illinois about 16 percent of households lost power for a day or more in 2024. Worth asking how a new furnace and thermostat come back once the power does.
- 8 months
- October through May, your furnace is on duty
- 20°F
- the average winter night it heats against
- 88%
- of homes here heat with gas, so most furnaces here burn gas
- 80% AFUE
- the federal minimum any new unit must meet
NOAA nClimDiv, 1991–2020 normals
A high-efficiency gas furnace would save about $130 a year to run in Will County compared with a gas furnace.
Estimates for a typical Will County home, from EIA household energy data, Illinois fuel prices and NOAA climate normals. Your home will differ.
In Illinois, HVAC licensing for homes is left to the cities and towns.
Will County does not license HVAC contractors itself. Whatever rule applies comes from the city or township the house sits in, so the protection in place depends on the address, not a statewide standard.
For a furnace install, what stands in for that is the permit process. Most cities and counties in the area require a permit from the local building office for a furnace replacement, with an inspection once the work is done. That inspection is what catches a bad gas connection or improper venting, the part of this job that actually puts a house at risk. Almost 9 in 10 homes in Will County heat with gas, so that check matters here more than in most places.
Source: Illinois General Assembly
- What size furnace does my house need?
- A contractor has to measure your house to answer that, not guess from its square footage. Sizing depends on how much insulation you have, how many windows you have and which way they face, your ceiling height, and how much air leaks in and out. A furnace that's too big cycles on and off too fast and never runs long enough to heat evenly. One that's too small runs constantly and still can't keep up when it's 20°F outside. The contractor will do a load calculation on your actual house to get the right number.
- How do I know it's time to replace my furnace?
- Age is the first thing to look at, along with how often it's needed repair lately. Once a furnace is old enough that parts are failing every year or two, repairs stop being worth paying for. Watch for uneven heat between rooms, a furnace that runs longer than it used to, or a yellow flame instead of blue. If a repair costs a large share of what a new furnace would, replacing it makes more sense than fixing it again next year. With heat needed here from October through May, a furnace on its last legs is a bigger risk than it would be somewhere with a shorter season.
- Is a high-efficiency furnace worth it?
- It depends on how much you use it and how your house holds heat, and a contractor can walk through that math with your specific situation. What's true everywhere is that any non-weatherized gas furnace made on or after November 19, 2015 has to reach at least 80 percent AFUE, so even a standard furnace today wastes less gas than an old one. High-efficiency models go above that minimum, which matters more in a place that needs heat 8 months of the year like this one does. The tradeoff is usually cost against how long you'll own the furnace, so ask a contractor to run the numbers for your house before deciding.