How to get fuel-burning appliances checked for venting
Book a qualified technician once a year for a fuel-burning appliance inspection covering furnaces, boilers and water heaters along with their flues. CPSC says they should check chimneys and flues for blockages, corrosion and loose or disconnected sections. A service call with testing runs about $90 to $450. If a CO alarm sounds, get outside first.
What a fuel-burning appliance inspection checks
Carbon monoxide has no smell, so a venting problem can go unnoticed. CPSC reports more than 200 U.S. deaths a year on average from CO produced by consumer products other than vehicles. The aim of this visit is to prove that everything burning fuel in your home sends its exhaust outside.
Based on what CPSC and ENERGY STAR describe, the technician should:
- Trace each vent and flue for blockages, corrosion, and loose or disconnected sections
- Check gas or oil connections, gas pressure, burner combustion and the furnace heat exchanger
- Run startup and shutoff to confirm safe operation
- Check connectors shared by more than one appliance, such as a furnace and water heater on one flue
Ask about the water heater by name, since a heating tune-up may only cover the furnace. If you've just replaced an appliance with a different type or size, NFPA 211 calls for a Level II chimney inspection, so the old flue may not suit the new unit.
Gas appliance inspection cost
| Service | About what it costs | Notes |
|---|---|---|
| Basic tune-up | $75 to $250 | May not include a venting review, so ask |
| Service call with diagnostics | $90 to $450 | Testing and a performance check |
| Standard service call fee | $60 to $120 | Added to diagnostic or repair charges |
These are 2026 national estimates from Pick HVAC for general HVAC service. These guides don't price a stand-alone venting check, so ask for a written quote covering every appliance.
Who to hire for a gas appliance inspection
- Use a licensed pro. CPSC says most fuel-burning appliances should be installed by professionals, and warns against servicing them without the right knowledge and tools.
- Ask if they measure CO and check draft on every appliance.
- Make sure one company covers the furnace, boiler and water heater, or book two.
- For a wood stove or fireplace, use a certified chimney sweep instead.
Questions to ask after a venting check
- Which appliances did you test, and what were the readings?
- Is any vent corroded, loose or sloped incorrectly?
- Does any appliance share a flue?
- Did past renovations block or change a vent?
- Are my CO alarms in the right places?
Signs of a blocked flue and other red flags
- Rust, soot or scorch marks around a vent or draft hood.
- Vent pipes that are loose, sagging or held together with tape.
- An inspection that skips the water heater.
- Unvented heaters in bedrooms. CPSC says not to run them in rooms where people sleep.
- A handyman offering to reconnect a gas line.
If a CO alarm sounds, don't look for the source. Get outside, call 911 or the fire department, count heads, and stay out until responders say it's safe. Don't run the suspected appliance until it's been serviced. Headache, nausea and dizziness with no fever can be CO symptoms, so leave and see a doctor. If you smell gas, leave and call from outside.
How to prepare for a fuel-burning appliance inspection
- List every flame
Note the furnace, boiler, water heater, gas dryer, range, fireplace and any generator.
- Check your alarms
CPSC recommends CO alarms on every level and outside sleeping areas, ideally interconnected, and not in kitchens or right above fuel-burning appliances.
- Book the visit
Ask for all appliances to be inspected, including flues and vents.
- Clear the area
Move stored items, and keep paint and gasoline well away from the water heater and furnace.
- Walk the outside vents
Keep dryer, furnace, stove and fireplace vents free of snow and debris, per USFA.
- Review the results
Get readings in writing and fix safety items before using the appliance again.
- Recheck after any renovation
CPSC says to confirm vents aren't blocked and appliances work properly once the work ends.
What homeowners say about a fuel-burning appliance inspection
Gas piping tops DIY forum lists of jobs not to do yourself. A wrongly tightened fitting can leak. Leave gas connections to a licensed pro even if the appliance swap looks easy. (DIY Stack Exchange)
How often should gas appliances be inspected? More answers
How often should gas appliances be inspected?
CPSC says to have your heating system professionally inspected and serviced once a year, including chimneys and flues. Ask the technician if your water heater should be on the same visit.
What are the signs of a blocked flue?
Rust or soot near the vent can be a clue, but CO itself can't be seen or smelled. Working CO alarms and a yearly inspection are the reliable protection.
What should I do if my CO alarm goes off?
Get outside to fresh air right away and call 911 or the fire department. Don't go back in until responders say it's safe. If it sounds again within 24 hours of returning, repeat this and have a qualified technician inspect all fuel-burning equipment.
What you’ll need
Sources: CPSC, U.S. Fire Administration, ENERGY STAR, NFPA, pickhvac.com
General guidance for U.S. homes, not professional advice. For gas, electrical and structural work, call a licensed pro.