Question? Just ask us!
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
InspectAPedia ® Home
AFUE DEFINITION, RATINGS
AGE of CHIMNEYS & FIREPLACES
AGE of HEATERS, BOILERS, FURNACES
BACKDRAFTING HEATING EQUIPMENT
BOILER COMPONENTS & PARTS
BOILER CONTROLS & SWITCHES
BOILER NOISE SMOKE ODORS
BOILER OPERATING PROBLEMS
BOOKSTORE - InspectAPedia
CARBON DIOXIDE - CO2
CARBON MONOXIDE - CO
CHIMNEY INSPECTION DIAGNOSIS REPAIR
COMBUSTION AIR for TIGHT buildings
COMBUSTION GASES & PARTICLE HAZARDS
COMBUSTION PRODUCTS & IAQ
COMPLETE COMBUSTION, Stoichiometric
CREOSOTE FIRE HAZARDS
DEFINITION of Heating & Cooling Terms
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DIRECT VENTS / SIDE WALL VENTS
DRAFT HOODS - gas fired
DRAFT MEASUREMENT, CHIMNEYS & FLUES
DRAFT REGULATORS, DAMPERS, BOOSTERS
FIRE SAFETY CONTROLS
FIREPLACES & HEARTHS
FLAME COLOR, BLUE vs YELLOW COMBUSTION
FLOODED HEATING EQUIPMENT REPAIR
FLUE SIZE SPECIFICATIONS
FLUE VENT CONNECTORS
FUEL OIL TYPES & CHARACTERISTICS
FUEL UNIT, HEATING OIL PUMPS
FURNACE CONTROLS & SWITCHES
GALVANIC SCALE & METAL CORROSION
GAS BURNER Flame & Noise Defects
GAS FIRED WATER HEATERS
GAS PIPING, VALVES, CONTROLS
HEATING LOSS DIAGNOSIS-BOILERS
HEATING LOSS DIAGNOSIS-FURNACES
HEATING OIL PIPING TROUBLES
HEATING OIL TANKS
HEATING SYSTEM NOISES
HEATING SYSTEM TYPES
HIGH EFFICIENCY BOILERS/FURNACES
HOT WATER HEATERS
LOW VOLTAGE BUILDING WIRING
LOW VOLTAGE TRANSFORMER TEST
LP & Natural Gas Safety Hazards
MANUALS & PARTS GUIDES - HVAC
Natural Gas Combustion
NO HEAT - BOILER
NO HEAT - FURNACE
NOISE, DUCT VIBRATION DAMPENERS
NOISE, HEATING SYSTEMS
NOISE, WATER HEATER
ODORS & SMELLS DIAGNOSIS & CURE
ODORS FROM HEATING SYSTEMS
OIL BURNER FUEL UNIT
OIL BURNER INSPECTION & REPAIR
OIL BURNER NOISE SMOKE ODORS
OIL BURNER SOOT & PUFFBACKS
OIL FILTERS on HEATING EQUIPMENT
OIL FUEL TYPES & CHARACTERISTICS
OIL HEAT FIRE SAFETY CONTROLS
OIL LINE CLOGGING FIX
OIL LINE QUICK STOP VALVES
OIL LINE SAFETY VALVES
OIL FILL PIPE LEAKS
OIL PUMP FUEL UNIT
PLASTIC HEATER VENT
PULSE COMBUSTION HEATERS
RELIEF VALVE LEAKS
RELIEF VALVES - TP Valves on Boilers
RELIEF VALVES - STEAM TP VALVES
RELIEF VALVES - Water Heaters
Reset Switch - Heater Primary Control
Reset Switch Broken - Quick RepaiR
RESET SWITCH - ELECTRIC MOTOR
Reset Switch - Stack Relays
SAFETY, HEATING INSPECTION
SAFETY RECALLS CHIMNEYS VENTS HEATERS
SOOT on OIL FIRED HEATING EQUIPMENT
SPILL SWITCHES - Flue Gas Detection
STACK RELAY SWITCHES
STAIN DIAGNOSIS on BUILDING INTERIORS
STEAM HEATING SYSTEMS
THERMAL EXPANSION of HOT WATER
THERMAL EXPANSION of MATERIALS
THERMAL MASS in BUILDINGS
THERMOSTATS, HEATING / COOLING
THERMOSTATS, WATER HEATER
TRANSITE PIPE CHIMNEYS & FLUES
VIDEO GUIDES: Heating System Videos
WINTERIZE A BUILDING
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
This article explains the methods of measurement and proper adjustment settings for draft regulators or barometric dampers 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.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved.
Barometric dampers used on oil-fired heating appliances (furnaces, boilers, water heaters) are discussed in detail beginning at DRAFT REGULATORS, DAMPERS, BOOSTERS. Details about draft control for gas fired heating systems, including furnaces or boilers, are discussed at Furnace Draft Hood on gas fired equipment. Readers should also see CHIMNEY INSPECTION DIAGNOSIS REPAIR and FLUE VENT CONNECTORS, HEATING EQUIPMENT for inspection, defect identification, and repair suggestions for chimneys and flues. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.
As we explain at our home page for this topic, DRAFT REGULATORS, DAMPERS, BOOSTERS, a barometric draft control, also called a "damper" or barometric damper, is a hinged, weighted door on an opening at a heating flue.
The door opens or closes to let extra air into the flue to assure that the draft in the flue remains constant at the proper setting needed for proper heating system operation.
Where do we Measure Chimney or Flue Draft & What is the Correct Draft Measurement at Oil Fired Heaters?
Normally we measure draft at two locations: over the fire or in the combustion chamber where typically we may see -0.02 to -0.03 inches of water column pressure, and in the breech or at the stack pipe (properly, the flue vent connector) measured just a few inches above the boiler or furnace top, and before the barometric damper itself.
[Click to enlarge any image]
Notice that we're using negative numbers for draft measurement - that's because gases in the flue are moving up, up, and away, like superman, and onwards out of the building - away from the heating equipment. The gas pressure in the chimney needs to be less than atmospheric pressure in the boiler room for gases to leave.
This sketch of a barometric damper used on oil fired heating equipment (heating boilers or water heaters) is provided courtesy of Carson Dunlop Associates.
In the breech we want to see about -0.05 inches WC pressure. If the
breech draft is too low the combustion process and venting process may be inadequate, and if the draft measured in the
breech is lower than the draft measured over the fire, the oil burner and combustion chamber are operating under
pressure - which is often a problem on residential heating systems since few of them are designed to work this way. Thanks to L. - for correcting our WC pressure data.
At this New York home (photos just above and below) the draft in the breech was running at about -0.02" w.c. - it should have been at least twice that amount. At below left you can see that the draft was hovering around 0.02" and at below right you can see our connection of the draft gauge sensing probe into the flue vent connector just above the boiler top.
How Much Draft do we Want at an Oil Burner Fired Heating Boiler, Furnace, or Water Heater?
In sum the draft we typically see on oil fired heating equipment is
Correcting Inadequate Chimney Draft - extending the flue height
In the heating industry, traditionally draft measurements around -0.02" w.c. are considered "low", and around-0.06" w.c. are "high" draft levels. After we replaced the too-short chimney with one of proper height, and with a draft regulator (barometric damper) now installed at the boiler top, our measurement showed that we had a good draft in the flue vent connector - almost 0.06" w.c. in the breech (photo above left). In our chimney replacement photo (above right) the new chimney extending 24" above the roof of a new addition (green arrow) is much taller than the original 20" chimney (red arrow). That's how we got good draft in the new chimney set-up.
Weight location & adjustment on barometric draft controls
Frequently Asked Questions (FAQs) about measuring chimney draft
Questions & answers or comments about the procedure for measuring chimney or flue draft and the related settings for draft regulators and barometric dampers on heating equipment;
Ask a Question or Enter Search Terms in the InspectApedia search box just below.
Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.