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What Is Furnace Replacement?
Furnace replacement is the removal of your existing furnace and the installation of a new one in its place, including the venting, gas connection, condensate handling, electrical, and controls that make it run safely.
Furnace installation and furnace replacement are the same job at the point of workmanship; the difference is what comes before it. An installation into new construction starts from plans. A replacement starts from an existing system, and it inherits every decision the last installer made, right and wrong: the sizing, the duct connections, the vent routing, the placement of the shutoffs.
That inheritance is exactly where replacements go wrong. If the original unit was oversized, mis-vented, or sized off a sea-level table, copying its nameplate copies the mistake, and your new furnace spends the next 15 years repeating it. McCormick treats every replacement as a fresh sizing exercise instead. We look at the house, not just the old equipment, before we specify anything.
Furnace replacement is one part of our full range of heating services in Greeley, CO.
What Are the Signs Your Furnace Needs Replacing Rather Than Repairing?
Furnace replacement becomes the smarter path when the unit is 15-20 years old and failing repeatedly, when the heat exchanger is cracked, or when the system was never sized correctly to begin with. Here's what each of those looks like from inside your home:
Sign #1
It's 15-20 years old and this is the second repair this season. A furnace at that age isn't unlucky; it is finished. Northern Colorado’s heating season runs from about October to April, and if you wait until it dies during a January cold snap, you're calling for help the same week as everyone else whose furnace just quit. Replace it before winter, and you pick the day. Wait, and the weather picks it for you.
Sign #2
A technician has found a cracked heat exchanger. A cracked heat exchanger can allow combustion byproducts, including carbon monoxide, into the air your family breathes. This is the one sign where "repair vs. replace" stops being a debate. The system should not run in that condition.
Sign #3
Some rooms have never heated evenly since the day the system went in. If the back bedrooms have been cold for 15 years, the problem isn't a failing part. Chronic hot-and-cold rooms usually trace back to the original sizing or duct design, and no repair fixes a design error. A properly load-calculated replacement can.
Sign #4
You have an 80% AFUE builder-grade unit installed in the mid-2000s. These were fitted by the truckload during the building boom, chosen by builders rather than homeowners, and most are now past the age where they run the way they were rated to.
Sign #5
The furnace short cycles. This is the signature of a unit that was oversized when it was fitted. It blasts heat, overshoots the thermostat, and shuts down before the air ever reaches the far rooms, then the constant starts wear out the very components that keep failing.
If your furnace is younger, structurally sound, and simply misbehaving, repair may still be the right call. Our furnace repair team will tell you honestly which side of the line you're on, because a replacement sold to someone who didn't need one comes back to us in reviews, and we like our reviews the way they are.
How Long Does a Furnace Installation Take?
Most furnace installations in Greeley are completed in a single working day, from removal of the old unit to full commissioning of the new one. Your technician arrives in the morning, and by evening you have heat.
Occasionally something unforeseeable pushes the finish into a second day, like a venting complication hidden behind a wall, a component that arrives out of spec, or a gas line that isn't what the original paperwork claimed. When that happens, we tell you the moment we know, not at 5 PM with a shrug.
What Size Furnace Does a Northern Colorado Home Need?
Most Greeley-area homes need a furnace in the 60,000–100,000 BTU range, but the only number that matters for your house comes from a room-by-room Manual J load calculation, adjusted for Front Range altitude. Square-footage rules of thumb and the nameplate on your old unit both fail the same test: two homes of identical size with different insulation, window area, ceiling heights, and orientation can require different furnaces.
In Northern Colorado, one more factor makes this non-negotiable: every furnace loses rated heating output at Front Range altitude. Gas furnaces are rated at sea level, and the thinner air at Greeley-area elevations (roughly 4,676 to 5,000 feet) means the same unit delivers meaningfully less heat here than its label claims. A system sized off a sea-level table is not sized for your home. And a like-for-like replacement without a fresh load calculation simply repeats whatever error was made the first time, which is often why the old system short-cycled or left the back bedrooms cold.
Sizing also isn't just the furnace. The new unit has to match the ductwork it's connected to: a furnace that moves more air than the ducts can carry runs loud, strains its blower, and heats unevenly no matter how well it was chosen on paper. Where the load calls for it, we'll also talk through staged and variable-capacity options that run longer at lower output: the opposite of short cycling, and the difference between a house that's warm and a house that's warm everywhere.
McCormick measures the home, accounts for altitude derating, and sizes the new furnace to the load your house actually carries. For some homes, that conversation surfaces alternatives worth weighing: heat pump installation for homes ready to heat and cool with one system, or boiler installation where the home already runs on hydronic heat. We'll lay out what fits your house; the decision stays yours.
Furnace Replacement in Three Steps
Furnace replacement with McCormick asks three things of you. Everything else is on us.
Step 2
We measure your home and calculate the actual heating load — not a like-for-like swap off the old nameplate.
Step 3
We install, commission, and document the system, and register the manufacturer warranty for you.
What Happens on Installation Day?
Furnace installation day starts with your McCormick technician confirming the plan with you: what's being removed, what's going in, where the shutoffs and filter access will live, and roughly when each stage will happen. Then the work follows a fixed sequence:
1
Protection and removal. Floors and work paths are covered, the old furnace is safely disconnected from gas and electrical, drained, and hauled away. Disposal is on us, not on your curb.
2
Set, connect, and vent. The new furnace is set and leveled, then connected to gas, electrical, condensate, and venting. Each connection is checked against the manufacturer's specifications. If the old venting or gas configuration wasn't right, this is where it gets corrected instead of copied.
3
Commissioning. We verify gas pressure, temperature rise, airflow, and every safety control under real operating conditions, and we set up the thermostat so the system runs the way it was designed to.
4
Walkthrough and registration. Before we leave, you get a full walkthrough of the gas shutoff, filter location and replacement, and thermostat operation, plus the user manual. We also register your manufacturer warranty for you. Everything is left labeled, accessible, and clean.
That last step matters more than most homeowners realize: manufacturer warranty coverage generally requires documented annual service from the date of installation. Registration starts the clock, and a yearly furnace tune-up and maintenance visit keeps the documentation and the coverage intact for the life of the system. A warranty that lapses for lack of paperwork protects no one, so we build the paper trail from day one.
Why Choose McCormick for Furnace Installation in Greeley?
McCormick Heating & Cooling is a locally owned, residential heating company based right here in Greeley. We size for this altitude because we live at this altitude, and the technician who installs your furnace answers to a local owner, not a call center.
800+ reviews on Google from Northern Colorado homeowners — earned one installation at a time, and the reason we'd rather talk you out of a replacement you don't need than sell you one you'll regret.
Owner Jesse Trout — Colorado Native, HVAC Expert. McCormick isn't a franchise or a private-equity rollup. The name on the truck belongs to someone who lives here, heats a home here, and stands behind every job personally.
NATE & EPA Certified technicians perform every installation — certified by North American Technician Excellence, the industry's leading independent certification body. No subcontracted crews.
Authorized Armstrong Air dealer. Armstrong, a division of Lennox, has been building heating equipment since 1928, and our technicians install and service any major brand, from Armstrong to Goodman to American Standard.
Satisfaction Guaranteed on all jobs — if it isn't right, we make it right.
Emergency service available when a failure won't wait for business hours.
🚩 TRANSFORMATION PROOF
Where We Install Furnaces
Furnace installation and replacement from McCormick covers Greeley and the surrounding Northern Colorado communities, including Loveland, Longmont, Fort Collins, Fort Lupton, and Firestone.
Cold House. Old Furnace. One Call.
If your furnace has given you its last good winter, don't wait for the first hard freeze to make the decision for you. By then, you're competing with every other failed furnace in Weld County for a spot on the schedule. McCormick will measure your home, size the system for Front Range altitude, and have you heating again — installed, commissioned, and warranty-registered, usually in a single day.
McCormick Heating & Cooling · 2881 S 31st Ave #3, Greeley, CO 80631, United States · Mon–Fri 8am–5pm
