Family-owned · Furnace Installation & Replacement in Plainfield & the Western Suburbs
Furnace Replacement Service in Plainfield & the Western Suburbs
Your home is your fortress. We protect your comfort. A new furnace is a big decision made under a deadline more often than not — here's the real cost, the real math on repair vs. replace, and what a single install day actually covers.
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Heating
Furnace Installation & Replacement
Manual J and Manual D sizing on every install, permit filing handled for you, and a post-install combustion analysis before we leave.
Other heating services
Furnace Repair
$150–$600Furnace Installation & Replacement
From $3,500Heat Pump Repair & Installation
From $4,500Heating Maintenance & Tune-Up
$89–$150
Furnace Installation & Replacement
Full furnace replacement with the venting, gas line, and combustion air done to code — not a bolt-on swap.
A furnace replacement is only as good as everything around it. We size the flue, verify the gas supply, and check that your ductwork can actually move the air the new unit produces.
- Manual J and Manual D sizing
- Venting and combustion air to code
- Permit filing and inspection
- Post-install combustion analysis
FortHouse runs a furnace replacement service built around the decision, not the sale — we explain when repair still makes sense before quoting a replacement. Every job includes proper sizing, a written equipment scope, and installation by the crew that answers the phone.
Most straightforward installs finish in a single day: sizing and airflow review, old furnace removal, new venting if you're moving to a high-efficiency unit, and final startup checks before we call it done. The full furnace cost and timeline breakdown goes deeper; if the AC is also aging, compare the combined HVAC replacement option before deciding.
Signs it's replacement, not another repair
A few things push the decision toward replacement even before a repair estimate is written:
- A cracked heat exchanger — the one furnace failure that can put carbon monoxide into the air, and it gets replaced, not repaired, full stop.
- A second repair in one heating season — not because the second repair is expensive, but because a furnace failing twice a season is telling you something the first fix didn't address.
- AFUE below 80% — furnaces built before the mid-2000s often run 60–70% efficient; a modern 95%+ AFUE furnace can cut the gas portion of a heating bill by a third.
- The furnace is past 15 years old and the current repair costs more than roughly half of what a new furnace would run.
- A gas bill that's climbed with no change in weather or thermostat schedule — usually a furnace losing efficiency as it ages, not a rate hike.
What a real furnace replacement quote actually includes
Manual J and Manual D sizing so the new furnace is matched to your house, not just your old unit's tonnage — the same oversizing mistake that causes short cycling and wears out a furnace early. Venting and combustion air brought to code, not just bolted to whatever was already there. Permit filing and inspection, since nearly every township in the Chicago western suburbs requires one for furnace replacement. A post-install combustion analysis confirming the new unit is actually burning clean before we leave.
What furnace replacement actually costs
Real ranges, not a quote — the exact number depends on your ductwork, venting, and efficiency tier:
- Standard-efficiency (80% AFUE), straightforward swap: roughly $3,500–$5,500 installed.
- High-efficiency (95%+ AFUE), including the new PVC venting it requires: roughly $4,800–$7,500 installed.
- Ductwork modifications, if your existing ducts can't move the air a bigger or higher-efficiency unit produces: add $800–$2,500.
- Old furnace removal and disposal, and permit filing, should already be in an installed price — if either shows up as a separate add-on, ask why.
Standard vs. high-efficiency — the real tradeoff
A 95%+ AFUE furnace costs more upfront for one structural reason: it needs sealed PVC intake/exhaust venting instead of a metal flue, since the exhaust gas runs cool enough not to need one — that venting change is most of the price gap. It's usually worth it if you're staying in the house more than five years and your gas bills already sting in January; it's a harder case if you're replacing a 12-year-old 90%-efficiency furnace that's still running fine, since the payback period on the last five points of efficiency stretches out fast. The other high-efficiency path is a dual-fuel setup — a heat pump handles most of the season, and the furnace kicks in only on the coldest nights.
What installation day actually looks like
Most furnace replacements are a single day, start to finish:
- Manual J load calculation and Manual D duct check.
- Old furnace removal and disposal.
- New venting run, if you're moving to a high-efficiency unit — the step that occasionally adds a second day.
- Gas line and electrical connection, then startup and combustion analysis.
- Permit inspection — we file it and don't call the job done until it's signed off.
Replacement or repair — the actual math
The 50% rule is the actual industry shorthand: if a repair costs more than half of what a new furnace would run, or the furnace's age times the repair cost tops $5,000, replacement usually wins on value. If the furnace is closer to a $150–$600 repair and under 15 years old, a furnace repair visit is very likely the better call — this page exists for the other side of that math, not to talk anyone out of a repair that's still the right answer.
What to check before you book a furnace replacement company
A few real questions separate a company solving your problem from one selling a furnace:
- Do they run a Manual J, or just match your old unit's tonnage? Matching the old size just recreates whatever short-cycling or undersizing problem the old furnace had.
- Is the repair-or-replace math explained, or skipped straight to a quote? A company that doesn't ask about your current furnace's age and repair history is selling a furnace, not solving your problem.
- Are they licensed to pull permits in your specific township? Furnace replacement almost always requires one, and a company still learning your township's process on your job is a real risk.
- Who actually owns the company? We're family-owned, not backed by private equity — it changes whether the incentive is sizing the furnace correctly or hitting a sales number.
Furnace replacement across Plainfield and Chicago's western suburbs
We run furnace replacements across the whole service area every week — which means the crew showing up already knows the local permit process, which townships require a separate mechanical permit, and how the housing stock in this specific area was originally ducted, since a lot of homes out here were built for an 80% furnace and need duct changes to run a 95% one well. See our Plainfield-specific furnace installation page for local permit and housing-stock detail if that's where the job is.
Service area
Furnace Installation & Replacement across Chicago's western suburbs.
Common questions
Furnace Installation & Replacement — frequently asked.
How much does furnace replacement cost?
Most straightforward swaps run $3,500–$5,500 for a standard-efficiency furnace, or $4,800–$7,500 for high-efficiency with new venting. Ductwork modifications, if needed, add $800–$2,500 separately. Every quote is written and based on a walkthrough of your specific system.
Should I repair or replace my furnace?
Run the 50% rule: if a repair costs more than half of what a new furnace would, or the furnace's age times the repair cost tops $5,000, replacement wins on value. A cracked heat exchanger, a second repair in one season, or AFUE under 80% all push the decision toward replacement even when the math is close.
How long does a furnace replacement take?
One day for a standard swap in most cases. Add a half to full day if you're switching to a high-efficiency furnace that needs new PVC venting, or if ductwork needs modification for the new unit's airflow.
Is a permit required to replace a furnace?
Nearly every township in the Chicago western suburbs requires a mechanical permit for furnace replacement, including gas line and venting work. We file it and schedule the inspection as part of the job.
Is a high-efficiency furnace worth the extra cost?
Usually, if you're staying in the house more than five years and current gas bills already run high — the payback period is faster than people expect once the venting cost is the only real premium. It's a harder case if you're replacing a furnace that's already 90%+ efficient and still running fine.
What areas do you cover for furnace replacement?
Plainfield, Naperville, Oswego, Yorkville, Bolingbrook, Wheaton, Lisle, Minooka, Shorewood, and Aurora, plus the rest of Chicago's western suburbs. If you're just outside that list, call anyway — we make exceptions for a reasonable drive.
How we work
You call, we diagnose with real measurements, you get a flat written number before anything starts, then we fix it and put the post-repair readings on the invoice next to the originals. See the full four-step process.
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