Furnace Installation in Decatur, IL
A new furnace here will run from October through April every year. Tell us about the house, and a licensed contractor who covers Macon County will get in touch.
Tell us about the job
It takes about a minute.
Seven months of heat, and nights near 22 degrees
Decatur homes need the furnace on from October through April. That's seven months a year the burner has to work, on nights that average 22°F through the coldest stretch of winter. A new furnace here has to hold up to that kind of run time, year after year.
Most homes in Macon County heat with gas, and any new non-weatherized gas furnace has to reach at least 80 percent AFUE, the federal minimum since November 2015. Power matters too. Illinois saw 16 percent of households lose power for 24 hours or more in 2024, and the last ten years brought 10 winter storms and 109 damaging wind events through the area. When the power goes out in the cold, a furnace that depends on it goes out with it.
- 7 months
- October through April, your furnace is on duty
- 22°F
- the average winter night it heats against
- 74%
- 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 $110 a year to run in Macon County compared with a gas furnace.
Estimates for a typical Macon 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.
Illinois has no state HVAC license, and Macon County does not run its own program either. Whatever rule applies to this job comes from the city, not the county or the state. There is no license to check on a state database and no state exam behind the person doing the work.
What stands between you and a bad furnace installation here is the permit process. Most building departments require a permit before a furnace is replaced, and an inspection once the work is done, and that inspection is what catches a bad gas connection or a venting mistake before it becomes dangerous. That inspection is not a licensing check. It is someone from the local building office looking at this specific job. In Macon County, 73.5% of homes heat with gas, so a safe connection on a job like this one is not a small detail.
Source: Illinois General Assembly
- What size furnace does my house need?
- A contractor has to work this out with a load calculation, not a chart based on square footage. That calculation looks at how much heat your house loses through its walls, windows, attic and ductwork, then sizes the furnace to match. A furnace that's too big will short cycle, heating the house in bursts and wearing out faster. One that's too small will run constantly and still leave you cold on the nights that hit 22°F. Get the load calculation done rather than guessing from the old unit's size, since that one may have been wrong too.
- How do I know it's time to replace my furnace?
- Age is one sign, alongside rising repair frequency, uneven heat between rooms, and a furnace that runs longer to hit the same temperature it used to. Homes here need heat from October through April, so a furnace on its way out gets tested hard for seven months straight. If a repair is priced close to what a new furnace would cost, replacement is usually the better move. A contractor can look at your furnace's condition and history and tell you which side of that line you're on.
- Is a high-efficiency furnace worth it?
- It depends on how long you plan to stay in the house and how much you run the furnace. Every non-weatherized gas furnace made since November 2015 has to hit at least 80 percent AFUE, so that's the floor, not the high end. High-efficiency models are rated above that floor, meaning less of the gas you burn goes out the flue instead of into your house. With winter lows here averaging 22°F and heat needed from October through April, a furnace here runs more hours over the year than one in a milder climate, which gives the higher efficiency more time to pay back. A contractor can run the numbers against your current gas use and tell you what makes sense for your house.