How Much Does A New HVAC System Cost?

Let’s be honest: nobody wants to replace their HVAC system. It’s not exactly the kind of purchase you daydream about. But when your furnace is blowing cold air in January, or your AC gives up in the middle of an eastern Idaho summer, suddenly it becomes the most important thing in the world. So you start Googling: “How much does a new HVAC system cost?”

RSJ Mechanical gets this question every single day, and we’re going to give you a real, honest answer. Spoiler: there’s no one-size-fits-all number. But don’t click away yet, because we’re going to walk you through everything that affects the price, and more importantly, show you how we make it affordable for families right here in Idaho Falls and the surrounding area.

How Much Does a New Furnace Cost?

Your furnace is the heart of your home’s heating system, and replacing it is one of the most common calls we get, especially after those brutal Eastern Idaho winters do their damage.

A new furnace installation typically ranges from $5,000 to $7,500 or more, depending on several factors:

The size of your home. A furnace is sized by BTU output, and a larger home needs more heating capacity. Installing the wrong size (too small or too large) causes inefficiency, higher energy bills, and premature wear. We always perform proper load calculations to make sure you get exactly what your home needs.

The efficiency rating (AFUE). Furnaces are rated by Annual Fuel Utilization Efficiency. A standard unit might run at 80% AFUE, while high-efficiency models reach 96–98% AFUE. The higher the rating, the more you’ll save on monthly gas bills, which can actually offset a higher upfront cost over time.

Single-stage vs. two-stage vs. variable-speed. Single-stage furnaces are your most basic option: on or off, full blast. Two-stage and variable-speed units run more quietly, maintain more consistent temperatures, and are gentler on your system long-term. They cost more upfront but deliver noticeable comfort improvements.

Labor and installation complexity. If your existing ductwork needs modifications, or your home has unique installation challenges, that can affect the overall price.

The bottom line? There’s no firm price we can quote without seeing your home, but we promise there won’t be any surprises either. Which is why we offer free estimates.

How Much Does a New Air Conditioning Unit Cost?

When the temperature in Idaho Falls climbs into the 90s, your AC isn’t a luxury. It’s a necessity. If your current unit is over 12–15 years old, struggling to keep up, or breaking down repeatedly, it’s probably time to talk replacement.

A new central air conditioning installation generally runs between $5,000 to $7,500+, with the range driven by:

The size of the unit (tonnage). Residential AC units are measured in tons of cooling capacity, typically ranging from 1.5 to 5 tons. Again, proper sizing matters enormously. An oversized unit will short-cycle, turning on and off too frequently, while an undersized unit will run constantly and still not cool your home properly.

The SEER2 rating. SEER2 (Seasonal Energy Efficiency Ratio) is the efficiency standard for modern AC units. The higher the SEER2 rating, the more efficient the system. Higher-efficiency units cost more upfront but can dramatically reduce your monthly energy costs, especially during peak summer months.

Whether your coil or air handler needs replacement. Sometimes when replacing an outdoor condenser unit, the indoor components (the evaporator coil or air handler) also need to be upgraded to match the new system. Mismatched components can actually void warranties and reduce efficiency.

Refrigerant lines and electrical work. If your existing refrigerant lines are old or need rerouting, or if your electrical panel needs an upgrade to handle the new unit, that’s additional cost to factor in.

How Much Does a Full HVAC System Replacement Cost?

If both your furnace and air conditioner are getting up there in age, you’ve probably started to wonder how much does a new HVAC system cost? Replacing them together is often the smartest financial move in this instance, and here’s why.

A complete HVAC system replacement (furnace + AC) typically falls in the $10,000 to $17,000+ range, but bundling both units at the same time often saves you money compared to replacing each one separately over a few years. You also benefit from:

• Matched components that work together efficiently
• One installation visit (saving on labor costs)
• New warranties on the full system, including a one-year labor warranty up to ten year warranty on parts
• Consistent performance across all seasons
• Potential rebates and incentives for high-efficiency paired systems

When you replace both at once, we can also assess your ductwork, thermostat, and overall system design to make sure everything is working as one cohesive unit. A brand-new furnace pumping air through leaky, 25-year-old ducts isn’t going to perform the way it should, and we’ll tell you that honestly.