What We Look For (And What We Don’t): Heating Systems — From Pilot Lights to Furnace Filters

It’s always funny to me how many different ways there are to heat a house—and how few of them actually work when I show up. From forced air to boilers to radiant floors, I’ve seen it all. Some are modern marvels, some are 40 years old and just praying for retirement. My job? Test it safely and report what I find. That’s it. I'm not tuning it, I'm not repairing it, and I’m definitely not voiding your warranty by poking where I shouldn’t.

The Systems I Commonly Inspect

Here’s a short list of what I’ve tested, activated, or called out over the years:

Gas furnaces – Most common. I check the thermostat, run the system, inspect flame visibility, venting, and filter access.
Electric furnaces – Quieter, but I still test for function, heat output, and safe wiring.
Heat pumps – These reverse depending on the season. If it’s cold out, I can only test heating, and vice versa.
Boilers and hydronic systems – I check for heat at radiators, look for leaks, rust, signs of pressure issues. I don’t test expansion tanks or bleed radiators.
Radiant floor heat – Electric or water-based. If it’s working, my thermal camera helps confirm. If it’s not accessible or off, I report limitations.
Wall and baseboard heaters – Electric or gas. I test for function and clearance but don’t disassemble.
Wood stoves, pellet stoves – Visually inspected only. I don’t light fires or confirm chimney sweep maintenance.
Solar thermal systems – Extremely rare, but I’ve seen them. Usually tied to radiant floors or water. Inspected visually only; I don’t test pumps or storage tanks.

What I’m Looking For—And What I’m Not

✅ I’m looking for: operation, heat output, strange smells, burner flame condition, rust, corrosion, soot, venting issues, dirty filters, and safety hazards.
❌ I’m not looking to: service burners, adjust gas pressure, inspect internal exchanger coils, or confirm installation specs. That’s for HVAC pros.

Why You Might Need a Specialist

If I can’t get the system to turn on—or it runs poorly, smells off, or shows signs of damage—I’ll let you know. And you’ll want to call in a licensed HVAC contractor. They can scope the heat exchanger, run diagnostics, or tell you if the blower motor is about to die. I don’t guess. I document.

My Thermal Camera Helps Spot Hidden Heat (Or the Lack of It)

One of my favorite tools for heating systems is my thermal camera. I use it to verify warm airflow from registers, spot radiant floor patterns, and check for cold zones. It’s especially useful when floor heating is claimed but the seller “forgot” to leave it turned on. If it’s running, I’ll know. If it’s cold, you will too.

Access and Weather Limitations

If the thermostat is locked, the unit is shut off at the breaker, or it’s 100°F outside and the system is in cooling mode only, I document that and explain the limitation. I don’t override owner settings or force systems into operation that aren’t meant to be running. Heating system safety matters.

FAQs: What to Expect From the Heating System Inspection

Do you test every heating system?

I test every accessible, safe-to-operate system using normal controls. If it’s off, locked, or weather-restricted, I’ll explain why it wasn’t tested in the report.

Can you tell me how old the furnace is?

Yes—usually by decoding the serial number on the unit. Age helps indicate expected lifespan and upgrade timing.

Do you open up the furnace or boiler?

No. I remove the front service panel if it’s safe, but I don’t dismantle units or access sealed components. That’s HVAC territory.

What if the system doesn’t work?

I’ll report that clearly—and recommend a licensed HVAC technician evaluate the system. Heating repairs or replacements can be costly, and you need expert advice.

→ Next up: Post 18: Cooling Systems — Testing, Limitations, and What’s in Scope

← Previously: Post 16: Electrical Red Flags — Panels and Wiring That Worry Inspectors

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