The Furnace Tune-Up Checklist Most Companies Skip.

Houston winters are short. That's exactly why furnace tune-ups matter, your equipment sits idle 8 months a year, then you ask it to come on cold and run reliably for the first cold front in November. Most no-heat calls we run after the first freeze are on furnaces that "got tuned up" the month before.

So what's actually in a real tune-up? Here's the checklist our techs use, every visit, no shortcuts.

The 19 steps

Combustion and safety (the stuff that can kill you)

1. Check carbon monoxide at the registers. A digital CO meter, not a sniff. We log the numbers. Anything over 9 ppm in the airstream is a problem.
2. Inspect the heat exchanger with a borescope. Cracks here vent CO into your house. The borescope sees what a flashlight can't.
3. Check flue draft. A weak draft means combustion gases backflow into the house. We measure it.
4. Test the flame sensor and igniter. Microamp reading on the flame sensor, resistance check on the igniter. These are the #1 and #2 causes of mid-winter no-heat calls, replacing a failing one preemptively is the whole point of a tune-up.
5. Inspect burners for rust, debris, or spider webs. Spiders love gas valves in the off-season. We've seen them shut down brand-new furnaces.
6. Verify gas pressure (manifold and inlet). Manometer reading. Low pressure = poor combustion = soot and CO. High pressure = overfired equipment = cracked heat exchangers.
7. Combustion analysis. O2, CO, CO2, stack temp, and excess air. We tune the burner to manufacturer spec and write the numbers on the report.

Mechanical and airflow

8. Inspect blower wheel for dirt buildup. A dirty wheel can lose 30% of its airflow. We pull it and clean it if needed (extra charge, but we tell you first).
9. Check blower motor amp draw. Higher than nameplate = bearing wear or overload. Lower = belt or coupling slip.
10. Inspect belts and pulleys (older systems) or ECM motor (newer). Tension, wear, alignment.
11. Check static pressure across the system. Total external static is the single best indicator of duct or filter problems. Most Houston systems run at 2-3x the design max, a slow killer.
12. Replace or wash the air filter. Filter changes are part of every visit, no extra charge.
13. Inspect ductwork around the equipment for leaks and disconnections. Mastic-seal what's accessible.

Controls and electrical

14. Tighten all electrical connections. Loose connections heat up, arc, and eventually melt. Two minutes with a torque screwdriver, but most techs skip it.
15. Test the limit switch. The safety that shuts the burner off if the heat exchanger overheats. We block airflow temporarily and verify it trips.
16. Test the rollout switches. The safety that shuts the burner off if flame rolls out of the burner box. We verify continuity and trip points.
17. Calibrate the thermostat. Not just "does it work", actual cycle differential and anticipator settings.
18. Check condensate drain (high-efficiency furnaces). Clear the trap, run a few gallons through, verify it drains.
19. Document everything in writing. Pressures, temps, amp draws, CO numbers, and a photo of the heat exchanger. You get a copy.

What the $59 special usually does

If your tune-up takes less than 45 minutes, here's what almost certainly didn't happen:

• No combustion analysis (the meter alone is a $400 instrument and they don't carry it)
• No borescope of the heat exchanger
• No static pressure measurement
• No actual readings, just a sticker
• No written documentation of values for next year's comparison

The $59 ad is loss-leader pricing, it's designed to get a tech in the door so they can find an upsell. The actual tune-up is a brief, performative ritual.

"We tell our techs: when you leave a tune-up, the customer should be 90 minutes older and have a four-page report in their hand. If you're done in 30 minutes, you missed something. We'd rather lose the $59 than lose the customer's trust."

What about heat pumps?

Heat pumps don't burn fuel, so combustion items are skipped, but you add a separate refrigerant cycle inspection: subcooling, superheat, defrost cycle test, reversing valve operation, and outdoor coil cleanliness. Different list, same total time.

What you should ask before you book

Before you commit to any tune-up, ask:

1. "Will I get a written report with combustion numbers?"
2. "Do you do borescope inspection of the heat exchanger?"
3. "How long is a typical visit?"
4. "What's not included that might be an extra charge?" (Blower wheel cleaning, capacitor replacement, IFC board work, etc.)

If the answers are vague or rushed, find another company.

Bottom line

A tune-up is a real maintenance visit, or it's a sticker. There's not much in between. If you've been getting the sticker version for years and your furnace is more than 10 years old, get a real one this fall, there's a good chance we'll find something the cheap visits missed.

Want the real version? Our fall furnace tune-up is the full 19-step checklist. Comfort Club members get it free; non-members pay a flat fee and get the same complete report. 281-992-7866 or book a tune-up.