How to open and inspect a barometric damper and flue vent connector (C) Daniel FriedmanHow & Why to Open & Inspect Barometric Dampers & Draft Regulators on Oil Fired Heating Equipment

  • DRAFT REGULATOR SOOT INSPECTION - CONTENTS: How to inspect the oil fired boiler or furnace flue through the barometric damper opening. How to interpret the level of soot or debris inside of oil fired heating equipment chimneys and vents. Draft Regulators & Barometric Dampers: A Guide to Barometric Dampers on Oil Fired Boilers, Furnaces, Water Heaters: inspection, adjustment, cleaning, troubleshooting. Cleaning & maintenance guide for heating systems
  • POST a QUESTION or READ FAQs about Soot, Rust, Debris Seen in the Heating Flue
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

How to inspect through the heating appliance draft regulator or damper opening and why.

This article explains the procedure for opening and inspecting heating flues through the barometric damper or draft regulator, with particular emphasis on problems of soot & debris accumulation. Inspecting inside the boiler flue by the draft regulator opening gives very important information about the operating condition of oil fired heating equipment.

Green links show where you are. © Copyright 2017, All Rights Reserved.

How to open and inspect a barometric damper for Inspection

Photograph of a barometric damper draft regulator (C) Daniel FriedmanThis article discusses the simple but very useful step of just taking a quick look into the flue pipe through the barometric damper opening on oil fired heating equipment.

This article series answers most questions about central heating system troubleshooting, inspection, diagnosis, and repairs.

We describe how to inspect, troubleshoot and repair heating and air conditioning systems to inform home owners, buyers, and home inspectors of common heating system defects.

Details about draft control on oil fired heating systems (such as the oil fired heater shown in the photo above), including furnaces or boilers, are discussed
at DRAFT REGULATOR, DAMPER, BOOSTER on oil fired equipment.

At DRAFT MEASUREMENT, CHIMNEYS & FLUES we explain in detail how and where to actually measure the heating equipment draft in the course of checking on (or adjusting) the draft regulator.

The barometric damper or draft regulating device we are discussing here is normally used only on oil-fired heating equipment, not on gas-fired equipment. Details about draft control for gas fired heating systems, including furnaces or boilers, are discussed
at DRAFT HOOD, GAS HEATER on gas fired equipment.

Barometric dampers are devices used to regulate the draft on oil-fired heating equipment such as furnaces, boilers, or water heaters.

On oil fired equipment the barometric damper, or draft regulator is typically a round Tee inserted in the flue vent connector between the heating appliance and the chimney. The face of the tee contains a round "door" with an adjustable weight.

In our photo you may not be able to open this barometric damper - it is improperly installed (out of level), and has been improperly modified, indicating a draft problem with this heating system or its chimney.

The implications of sealed barometric dampers are explained at DRAFT REGULATOR, DAMPER, BOOSTER for oil fired equipment.

How & Why Should You Open & Inspect the Barometric Damper:

How to open and inspect a barometric damper and flue vent connector (C) Daniel FriedmanWhen I, the author (DF) first owned a home with a heating boiler I was so terrified of this rumbling flickering box in my basement that I didn't even walk near it. That was a mistake.

And we wasted lots of money on oil before we learned that just a few simple visual checks can tell a lot about how well our heating equipment is running.

So don't worry: it's easy to perform this step - anyone can do it if a barometric damper is actually installed where it should be. Just gently push the hinged door open with a finger, and shine a good flashlight inside to see what you can see.

Warning: of course if your oil fired appliance has been running recently, these parts are HOT and you could get burned. If the damper door itself is hot you can still look inside - just use a screwdriver or wire to push the door open rather than your finger as shown in our photo at left.

A barometric damper installed on a horizontal flue pipe will give a good view of the cleanliness of the flue interior as well as clues about rust and damage in the flue.

A barometric damper installed on a vertical flue pipe may still give a good view of the top of the heating boiler, furnace, or water heater, where you may see accumulated soot or debris, rust stains, or perhaps better news.

Guide to Interpreting Debris Visible in the Chimney Through the Cleanout or Draft Regulator

Debris in a stack pipe (C) Daniel FriedmanDebris visible in the flue vent connector (stack pipe) visible through the barometric damper draft control opening. If you see soot, rust flakes, and debris in the flue vent connector this means that the heating system needs to be cleaned and serviced.

If the heating system has "just been serviced" this debris means that service was incomplete.

A flue vent connector ((also called the "stack pipe" or "flue pipe") is the metal pipe that connects the oil fired heating appliance to a chimney in order to safely vent combustion gases outdoors.

A proper service procedure for oil fired heating equipment includes removal of the flue vent connector and thorough cleaning of all debris from these components as well as a visual inspection of the condition of the chimney to which the flue vent connector joins to send combustion products outside.

Our photo shows what was probably several years of accumulated soot, rust flakes, and debris in the flue vent connector of an oil-fired horizontal furnace in a wet moldy crawlspace. The owner thought that his system, which was almost impossible to access, had "just been cleaned".

Opening this damper and looking inside meant we literally "hit pay dirt". The dirt meant that the system needed to be cleaned, that the owner was paying for heat, but the heat was going up the chimney, not into the home -- as we explain a bit more below.

A hard to access heating system in a cramped nasty area rarely receives thorough cleaning and service. That was the case for this system.

The Significance of Soot, Rust, Debris Seen in the Heating Flue

Question: What is the significance of those "rusty flakes" in the photo of crud visible at the chimney base or through the barometric damper

When I cleaned our flue exhaust, I found 'chips' in the soot like the ones in the image. What are those? I thought they might be from the flue lining chipping off. Are they? - Jessica


The "chips" such as those in our photo are typically soot-coated rust if the flue is metal, or soot-coated flakes of the glazing that was protecting the interior of a clay tile lined chimney flue.

The implications of the chips are that the hard glazed coating is being lost and thus the flue is deteriorating. Just how deteriorated the flue is we can't say from a photo like this one, but it is an indication that a more expert chimney inspection is in order. Use a professional chimney sweep and ask for a complete inspection of the chimney flue interior.

Loss of the chimney tile surface exposes the chimney flue liner to an ever increasing rate of deterioration, especially in climates of harsh or freezing weather. When the chimney liner deteriorates that means that eventually it can become unsafe, risking flue gas leaks, carbon monoxide poisoning, or even sparks and a building fire.

See CHIMNEY CLEANOUT DOORS for more examples of things you may find at the bottom of a chimney when inspecting through the cleanout door, or if it's a "dead end flue" you may find these inspecting through the flue vent connector or, if the flue is without bends and elbows, you may be able to inspect right through the barometric damper such as in our photo above.

When & Why is soot or crud in the oil fired boiler or furnace flue a problem?

Oil flue soot - normal (C) Daniel Friedman

When we look in to the flue close to the heating boiler or furnace, such as at the barometric damper shown at the top of this page, it's normal to see a thin coating of soot on the interior of the metal flue pipe (photo at left and photo at page top). .

But thick soot in the flue, the chimney, or inside of the boiler or furnace heat exchanger is a problem (photo below).

Soot in oil burner flue damper tee (C) Daniel Friedman

Our photo of a soot problem indicator (left) shows soot accumulating in the oil burner flue of the heating boiler connected to the "too short" chimney discussed at Chimney Height & Clearance.

This boiler has a history of blowing soot out of the boiler room and through the garage of the home it serves. This same soot is, of course, accumulating inside the heating boiler itself.

Because soot acts like an insulating coating, too much soot in a heating system causes both system operating problems problems and increased heating cost for the building.

These soot problems on oil fired heating equipment are discussed in detail at SOOT on OIL FIRED HEATING EQUIPMENT [link given just below]

Article Series Contents


Continue reading at SOOT on OIL FIRED HEATING EQUIPMENT or select a topic from the index of chimney articles listed above.

Or see CHIMNEY CLEANOUT DOORS for another spot where it may be possible to inspect for clues about the condition of a chimney and its safety.


Suggested citation for this web page

DRAFT REGULATOR SOOT INSPECTION at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher's Google+ Page by Daniel Friedman