When replacing an older furnace, choosing the right equipment involves more than comparing brands and efficiency ratings. The size of the equipment, its location, and how it connects to the home’s existing heating system can all affect installation time and cost. A recent propane furnace replacement at a rural Montana home is a good example of how selecting the right equipment can make a project simpler and more cost-effective.
Table of Contents
Replacing an Aging Propane Furnace
The homeowners had an older Concord propane furnace rated at 93% AFUE (Annual Fuel Utilization Efficiency). The furnace was located in the laundry room on the main floor, a convenient location for accessing the equipment but one where available space and existing connections were important considerations.
The property was in a rural area situated between the Montana towns of Fairfield, Power, and Greenfield. For homeowners outside larger communities like Great Falls, having a dependable heating system is especially important during Montana’s cold winters. When temperatures drop below freezing and the nearest town is some distance away, reliable heat provides valuable peace of mind.
Along with replacing the furnace, we also updated the home’s digital thermostat. The existing thermostat was approximately 15 years old, making it a reasonable time to consider replacement. While many digital thermostats can last 10 to 15 years or longer, replacing an aging thermostat during a furnace installation can help ensure the controls are compatible with the new equipment and functioning properly.
Why We Selected a Guardian 96% Efficient Furnace
One of the biggest considerations for this project was finding a replacement furnace that would fit well in the existing space. After comparing several equipment options, we selected a Guardian propane furnace rated at 96% AFUE.
The Guardian unit was almost identical in physical dimensions to the old Concord furnace. This was an important advantage because it reduced the amount of modification needed to accommodate the new equipment.
Choosing equipment with similar dimensions can help reduce changes to ductwork and other connections, although every installation still requires verification of proper airflow, venting, combustion air, gas supply, and manufacturer requirements.
In this case, the close physical match helped make the replacement straightforward and reduced the labor time required for the installation. That benefits the homeowner by keeping the project efficient without compromising the quality of the work.
What Does the Efficiency Upgrade Mean?
The new Guardian furnace is rated at 96% AFUE, compared with the old Concord’s 93% AFUE rating. AFUE measures how efficiently a furnace converts fuel into usable heat over a typical heating season.
| Furnace | AFUE rating | How much of $1 goes to heat vs out the exhaust* |
|---|---|---|
| Old Concord | 93% | $0.93 |
| New Guardian | 96% | $0.96 |
*Illustrative comparison based on rated AFUE, not actual operating costs.
Although a three-percentage-point improvement may seem small, the new furnace uses approximately 3.1% less fuel to deliver the same amount of heat, based on the rated efficiencies alone. Actual propane savings depend on weather, thermostat settings, home insulation, equipment sizing, and operating conditions.
The efficiency improvement is a nice benefit, but it wasn’t the only reason for selecting this furnace. In this project, the physical fit and reduced installation labor were equally important considerations.
For more information on furnace efficiency, the U.S. Department of Energy’s residential furnace guide explains AFUE ratings and other factors homeowners should consider when selecting heating equipment.
A Smooth Installation and Updated Controls
Overall, the furnace replacement went smoothly. The Guardian furnace’s similar dimensions helped simplify the changeover, allowing our technicians to focus on installing and checking the new equipment rather than spending additional time making extensive changes to the existing exhaust and ductwork connections.
The updated digital thermostat completed the project, giving the homeowners a fresh set of controls to go along with their new heating system.
This installation is also a good reminder that the most expensive or highest-efficiency furnace isn’t automatically the best choice for every home. A properly sized furnace that fits the existing installation and meets the homeowner’s needs can provide better overall value than an option that requires substantial additional work.
Furnace Replacement for Great Falls and Rural Montana
At Halcro Heating and Cooling, we believe in finding practical solutions that make sense for each homeowner. Whether we’re replacing a furnace in a Great Falls neighborhood or working at a rural property between small Montana communities, our goal is the same: reliable heating, quality workmanship, and clear explanations of the available options.
If your propane or natural gas furnace is getting older, isn’t heating reliably, or you’re considering an upgrade, we can help evaluate your existing system and discuss replacement options.
Learn more about our furnace services or contact Halcro Heating and Cooling to discuss your heating needs.
We serve Great Falls and surrounding communities within approximately 100 miles.
Technical Review
Reviewed by: Josh Halcro, Senior Technician
Company: Halcro Heating and Cooling, Inc.
Last reviewed: October 2026
Reviewed by the experienced HVAC professionals at Halcro Heating and Cooling, Inc. for technical accuracy and practical relevance. Our content draws on hands-on experience with HVAC installation, maintenance, and repair to help homeowners make informed decisions about their heating and cooling systems.