Replacing a furnace is one of the bigger decisions you will make as a homeowner, and it tends to arrive with a lot of questions. How do you choose between a furnace and a heat pump? How much does it cost? And what does the whole process even look like?
If you have already weighed repair against replacement and landed on a new system, or you are close, this guide walks through what to expect. (Still deciding? Our guide on how to decide between repairing and replacing your furnace covers that question in detail.) The goal here is to help you plan calmly and get the most out of your investment.
First, your three real options
For decades the answer in Colorado was simple: replace your gas furnace with another gas furnace. Today you have three genuine choices, and the right one depends on your home, your budget, and your priorities.
A high-efficiency gas furnace. The familiar option, and still a strong one. Modern furnaces run at 95 percent AFUE or higher, produce hot air quickly, and keep working no matter how far the temperature drops. If your home is already set up for gas and you want the lowest up-front cost, this is often the practical pick. The trade-off is that a furnace only heats, so you still need a separate air conditioner for summer.
An all-electric heat pump. A heat pump moves heat rather than burning fuel, and it works in both directions: heating in winter and cooling in summer, so one system replaces both your furnace and your AC. Today’s cold-climate heat pumps are engineered to deliver efficient heat well below freezing, which is exactly what a Colorado winter demands. They are remarkably efficient, often delivering three or more units of heat energy for every unit of electricity. The considerations are that they run on electricity, so the math depends on your rates, and a premium cold-climate unit can cost more up front than a basic furnace.
A hybrid, or dual-fuel, system. For a lot of Front Range homes, this is the sweet spot. A hybrid pairs a heat pump with a gas furnace and automatically uses whichever is more efficient at any given temperature. The heat pump handles mild and moderate days cleanly and cheaply, and the furnace takes over for the sharpest cold snaps. You get year-round efficiency with cold-weather muscle as backup. The trade-off is a higher up-front cost, since you are installing two heat sources.
Why proper sizing matters more than the brand
Here is the part a lot of homeowners never hear: the brand on the box matters far less than whether the system is correctly sized and set up for your home. A new system that is too large will short-cycle, wear out faster, and heat unevenly. One that is too small will struggle on the coldest days.
Correct sizing comes from a load calculation, often called a Manual J, which accounts for your home’s square footage, insulation, windows, layout, and more. This matters even more along the Front Range because of our altitude: furnaces have to be properly derated for the thinner air, and a system installed without that step can underperform for its entire life. A good contractor runs the numbers before recommending equipment, rather than simply swapping in whatever size you had before. At Go Green, a load calculation is included at no extra charge with every installation quote.
What goes into the cost
Every home is different, but a few factors drive what a replacement will run:
The type and efficiency of the system you choose. A standard-efficiency furnace sits at the lower end, while a premium cold-climate heat pump or a hybrid system costs more up front and tends to cost less to run.
The size and capacity your home actually needs, based on that load calculation.
The condition of your existing setup, including ductwork, venting, electrical, and the thermostat. Sometimes a replacement is a straight swap, and sometimes a few updates are needed to do the job right.
The complexity of the install, such as switching fuel types or relocating equipment.
A trustworthy contractor gives you clear, itemized pricing up front so there are no surprises, and explains why each line is there.
What the installation process looks like
Knowing the steps takes a lot of the stress out of it. A typical replacement looks like this:
In-home assessment and load calculation. We look at your current system, your home, and your comfort concerns, run the Manual J, and confirm what size and type of system fits.
Options and clear pricing. You get a straight walk-through of your choices, including furnace, heat pump, and hybrid where they make sense, with real pricing spelled out. No pressure, no scare tactics.
Installation day. Most straightforward furnace replacements are completed in a single day. We remove the old equipment, install and set up the new system, and make sure everything is running safely and correctly before we leave.
Walk-through. We show you how your new system works, confirm your thermostat is set up the way you want, and leave you with the documentation you need.
The case for planning ahead
The worst time to replace a furnace is the moment it dies, because that almost always happens on the coldest night of the year, when every company in the metro is booked for days and you are making a rushed, expensive decision in a cold house. Planning your replacement in advance means you can compare options calmly and schedule the install on your timeline. If your furnace struggled last winter or is pushing 15-plus years, this is the season to get ahead of it.
Frequently asked questions
How long does a furnace replacement take?
Most standard furnace replacements are completed in a single day. A more involved project, such as switching to a heat pump or hybrid system or modifying ductwork, can take longer, and we will tell you up front what to expect.
How long should a new furnace last?
A well-maintained gas furnace typically lasts 15 to 20 years. Staying on top of annual maintenance is the single biggest factor in reaching the upper end of that range.
Is a heat pump a good idea in Colorado’s cold?
Yes. The old concern about heat pumps struggling in real cold no longer applies to today’s cold-climate models, which are built to deliver efficient heat well below freezing. For many Front Range homes a heat pump or hybrid system is an excellent fit.
How do I know what size furnace I need?
Through a load calculation, or Manual J, which factors in your home’s size, insulation, windows, and layout, along with the altitude adjustment that matters here on the Front Range. It is far more accurate than simply matching the size of your old unit, and we include it at no extra charge.
Should I replace my furnace and air conditioner at the same time?
Often it makes sense, especially if both are aging. Replacing them together can simplify the install and ensure the two systems are properly matched. If your AC is still relatively new, a furnace-only replacement is perfectly normal. We will give you an honest take based on what you actually have.
Plan your replacement the smart way
Whether a furnace, a heat pump, or a hybrid system is right for you depends on your home, and the only way to know is to have someone look at it, run the numbers, and lay out your options honestly.
At Go Green Heating and Air Conditioning, we install and service all three, and we give straight recommendations with no pressure. Load calculation included at no extra charge.
Call us at 303-919-9292 or schedule a free quote online. Locally owned in Arvada, serving Denver and the surrounding metro.