Summary
This case study covers a November 2025 furnace replacement in Caldwell, Idaho, where a homeowner’s furnace cycled on and off without adequately heating the home. Express Plumbing Heating & Air diagnosed the issue, presented replacement options, and installed a Goodman GR9T800603AN two-stage gas furnace with a rebuilt furnace plenum and a smart Wi-Fi thermostat, completing the job in two days.
Key Takeaways
- A furnace that runs isn’t the same as a furnace that heats; cycling without a temperature rise signals a deeper equipment problem.
- Attic-installed furnaces add layout constraints (framing, insulation, ductwork) that affect replacement planning.
- Two-stage heating (like the Goodman GR9T800603AN, 80% AFUE) adjusts output to match demand instead of running at one level.
- Replacement scope included a rebuilt furnace plenum, an Ecobee3 smart Wi-Fi thermostat, and HVAC surge protection.
- Full installation, from initial visit to completed work, took just two days.
- Every install was tested for gas pressure and temperature differential before the technician left the home.
Furnace Replacement in Caldwell: When the House Would Not Warm Up
A furnace that turns on can still leave a home struggling to reach a comfortable temperature. That was the concern at a Caldwell, Idaho, home when Express Plumbing Heating & Air visited in November 2025. The homeowners said their furnace would kick on sometimes but was not bringing the temperature up as it should. Over the previous week, the problem had gotten worse.
We reviewed the heating concerns with the homeowners, presented replacement options, and installed a new Goodman two-stage gas furnace. The project also included a smart thermostat, surge protection, and a rebuilt furnace plenum. Before leaving, our team tested the equipment and walked the homeowner through the thermostat.
The furnace was cycling without adequately warming the home
During the November 24 visit, our system advisor observed the furnace cycle a couple of times without meaningfully raising the temperature. This was the same problem the homeowners had been experiencing, giving us a firsthand view of their heating concern.
The existing furnace was installed horizontally in the attic, surrounded by roof framing, insulation, and ductwork. Our before photos show the Lennox furnace and its connections. That layout was part of the installation planning: the replacement needed to fit the available space and connect to the home’s existing system.
After discussing the options, the homeowners selected the middle replacement estimate. The installation was completed on November 26, two days after the initial visit.
A two-stage Goodman furnace for the replacement
For this project, we installed a Goodman GR9T800603AN gas furnace, an 80% AFUE model with two-stage heating and a multi-speed ECM blower. Two-stage heating gives the furnace a lower and a higher heating output rather than a single output level. That capability helps it respond to different heating demands.
The equipment choice was one part of the project. We also addressed the connections and controls included in the approved installation so the homeowner could use the new system as intended.
The work included duct connections and new controls
The approved work included rebuilding the furnace plenum, the chamber that connects the furnace to the duct system. This made the duct connection part of the replacement scope, rather than treating the job as only an equipment swap.
We also installed an Ecobee3 smart Wi-Fi thermostat and HVAC surge protection. The work order specifically called for checking the flue’s grade toward the roof. With the equipment located in the attic, access and the existing vent route were practical details the team had to account for.
The before-and-after photos show the change from the Lennox furnace to the new Goodman furnace in the same attic space. They also show how the furnace sits alongside the existing coil cabinet and surrounding ductwork.
Testing the installation and explaining the thermostat
Once the work was complete, our technicians tested equipment operation and checked gas pressures and the temperature difference across the heating system. The completion notes recorded satisfactory temperature checks and confirmed that the equipment had been tested before departure.
We then walked the homeowner through the thermostat, cleaned up the work area, and contacted the office to arrange the final inspection. Those steps completed the installation visit and gave the homeowner an introduction to operating the new controls.
A heating problem worth addressing before winter
For homeowners preparing to turn the heat back on this fall, this Caldwell project is a useful reminder to pay attention to how the house warms up. Hearing the furnace start does not tell the whole story. In this home, the concern was that the equipment cycled while the indoor temperature failed to rise adequately.
If your furnace turns on but your home is not warming up, contact Express Plumbing Heating & Air to schedule a heating evaluation. We serve homeowners in Caldwell, Nampa, Boise, and the surrounding Treasure Valley. Tell us what you are noticing and when it started so we can evaluate the problem and discuss the appropriate repair or replacement options for your home.
