Furnace Installation in Crystal Lake, IL
A new furnace here will run from October through May every year. Tell us about the house, and a licensed contractor who covers McHenry County will get in touch.
Tell us about the job
It takes about a minute.
Eight months of heat, and nights that drop to 17°F
Crystal Lake homes run the furnace October through May, eight months of the year. On winter nights that average 17°F, it's not cycling on for a quick boost. It's holding the line for hours at a stretch.
Any new furnace installed now has to meet 80.0 percent AFUE, the federal minimum for gas furnaces built since late 2015. Most homes here already heat with gas, so this is the standard a replacement is measured against. Power is worth planning around too. Illinois saw 16 percent of households lose power for 24 hours or more in 2024, and the region has logged 18 winter storms and 140 damaging wind events over the past ten years. A furnace that starts back up on its own once power returns matters on a night that cold.
- 8 months
- October through May, your furnace is on duty
- 17°F
- the average winter night it heats against
- 85%
- 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 McHenry County compared with a gas furnace.
Estimates for a typical McHenry 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 the person in your basement is licensed depends on the town, not the state. Illinois has no state license for this trade, so there is no single record covering McHenry County as a whole. What applies to the whole county is the permit. In most cities and counties, replacing a furnace needs a permit from the local building office and an inspection once the work is done.
That inspection is the thing that does not depend on which town the house is in. It is what catches a bad gas connection or a venting mistake, the part of a furnace install that is dangerous if it is done wrong. With 85% of homes in McHenry County heating with gas, that check matters to most houses here. It is not a license, but it is the protection the facts point to in a state that left licensing to the towns.
Source: Illinois General Assembly
- What size furnace does my house need?
- It depends on your square footage, your insulation, your windows, and how your home is laid out, so there's no single number that fits every house. A contractor works this out with a load calculation, not a chart based on square footage alone. Going too big wastes fuel and cycles on and off more than it should. Going too small means it runs constantly and still can't keep up when it's 17°F outside. Ask whoever quotes the job to walk you through the calculation for your house specifically.
- How do I know it's time to replace my furnace?
- Watch for rooms that won't heat evenly, a furnace that runs longer than it used to, or repairs that keep coming back. A breakdown in the middle of winter is a real risk here, with lows averaging 17°F from December through February and heat needed from October through May. Rising gas bills without a change in how you use heat can also point to a unit losing efficiency. If a repair costs a large share of what a new furnace would, that's usually the sign to stop patching it.
- 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. Homes here need heat from October through May, eight months of the year, so a furnace here works harder and longer than one in a milder climate. Every furnace made since November 2015 has to hit at least 80 percent AFUE, and high-efficiency models go higher than that, meaning less gas burned for the same heat. A contractor can walk you through the actual efficiency ratings available and what they mean for a furnace running that many months a year.