Furnace Installation in Belleville, IL
A new furnace here will run from October through April every year. Tell us about the house, and a licensed contractor who covers St. Clair County will get in touch.
Tell us about the job
It takes about a minute.
Belleville furnaces run seven months out of the year
October through April, your furnace is what stands between your house and a winter night that averages 26°F. That's most of the year spent asking one machine to keep up.
Most homes here heat with gas, and any non-weatherized gas furnace built since November 2015 has to hit at least 80 percent AFUE. A new install needs to clear that bar. It's also worth knowing that St. Clair County has seen 9 winter storms and 84 damaging wind events over the past ten years, the kind of weather that knocks out power. Across Illinois, 16 percent of households lost power for a full day or more in 2024. If your furnace needs electricity to run its blower and controls, an outage means no heat no matter how well the furnace itself is working.
- 7 months
- October through April, your furnace is on duty
- 26°F
- the average winter night it heats against
- 61%
- 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 $90 a year to run in St. Clair County compared with a gas furnace.
Estimates for a typical St. Clair 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.
That means whether a contractor needs a local license depends on the city or township the house sits in, not on any state list. Some places register or license HVAC contractors on their own, others leave it wide open, and there is no state record to check either way.
For this furnace installation, the protection that matters here is the permit. Most cities and counties in Illinois require a permit from the local building office before a furnace is replaced, and an inspection once the work is done, since a bad gas connection is the dangerous part of the job. In St. Clair County, 60.6% of homes heat with gas, and that inspection is what stands behind the installation, not a state license number.
Source: Illinois General Assembly
- What size furnace does my house need?
- The right size depends on your square footage, insulation, window count, and ceiling height, so there is no single number that fits every house. A furnace that is too big will short cycle, heating the house in bursts and wearing out faster. One that is too small will run constantly all winter and still struggle to keep up on the coldest nights here. A contractor works this out with a load calculation, not a rule of thumb based on square footage alone.
- How do I know it's time to replace my furnace?
- Age is the first thing to check. A furnace that is old and starting to need repairs more often is usually not worth fixing again. Watch for signs beyond age too. Rooms that heat unevenly, a burner flame that looks yellow instead of blue, or a furnace that cycles on and off more than it used to are all worth paying attention to. Homes here need heat from October through April, so a furnace showing these signs going into that stretch is worth replacing before it fails on a cold night.
- 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 each year. With 7 months of heating season here and winter lows averaging 26°F, a furnace here runs more hours per year than one in a milder climate, which is where higher efficiency pays back faster. Every new non-weatherized gas furnace sold today has to reach at least 80 percent AFUE by law, so the real choice is between that baseline and the higher-efficiency models above it. A contractor can walk through the specific models and what each one costs installed.