Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
Ask a Question or Search InspectAPedia
InspectAPedia ® Home
AIR CONDITIONING & HEAT PUMP SYSTEMS
BACKDRAFTING HEATING EQUIPMENT
BACKUP HEAT for HEAT PUMPS
BANGING HEATING PIPES RADIATORS
BLOWER FAN OPERATION & TESTING
BOOKSTORE - InspectAPedia
BTU USAGE MONITORS
CARBON MONOXIDE - CO
CIRCULATOR PUMPS & RELAYS
DIAGNOSE & FIX AIR CONDITIONER / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DIRECT VENTS / SIDE WALL VENTS
DRAFT REGULATORS, DAMPERS, BOOSTERS
DUCT SYSTEM & DUCT DEFECTS
ELECTRIC HEAT, DIAGNOSIS, REPAIR
ELECTRIC MOTOR DIAGNOSTIC GUIDE
FAN, AIR HANDLER BLOWER UNIT
FLOODED HEATING EQUIPMENT REPAIR
FLUE SIZE SPECIFICATIONS
GAS BURNER Flame & Noise Defects
GAS PIPING, VALVES, CONTROLS
GEOTHERMAL HEATING SYSTEMS
HEAT PUMPS, DIAGNOSIS, REPAIR
HEATING COST SAVINGS METHODS
HEATING OIL PIPING TROUBLES
HEATING OIL TANKS
HEATING SYSTEM NOISES
HEATING SYSTEM TYPES
LP & Natural Gas Safety Hazards
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
MOTOR OVERLOAD RESET SWITCH
NOISE, HEATING SYSTEMS
ODORS FROM HEATING SYSTEMS
OIL FILTERS on HEATING EQUIPMENT
OIL ODORS, LEAKY OIL TANK PIPING
OIL SPILL CLEANUP / PREVENTION
PLASTIC HEATER VENT
PUFFBACKS, OIL BURNER
RELIEF VALVE LEAKS
Reset Switch - Heater Primary Control
RESET SWITCH - ELECTRIC MOTOR
Reset Switch - Stack Relays
SAFETY, HEATING INSPECTION
SAFETY RECALLS, Chimneys, Vents, Heaters
SOLAR HEATING SYSTEM DESIGNS
SOOT on OIL FIRED HEATING EQUIPMENT
STEAM HEATING SYSTEMS
THERMOSTATS, HEATING / COOLING
VIDEO GUIDES: Heating System Videos
WINTERIZE A BUILDING
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
Automatic or manual HVAC air duct airflow controls: here we explain both manual and automatic heating and air conditioning ductwork zone dampers & airflow controls used to control airflow through heating or cooling ductwork. We describe how to find sometimes hidden manual duct dampers, and which way to set the duct damper lever to increase or decrease airflow through various sections of the ductwork and the building. We illustrate using air supply register controls to fine tune airflow in individual rooms or areas. We explain in detail automatic duct dampers and how they work. We also describe the use of individual airflow booster fans in the ductwork or in other locations to assure adequate cool or warm air supply in all areas.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Also see BALANCING AIR DUCT FLOW where we discuss how to find and correct building conditions such as open suspended ceilings, windows, doors, etc. that foul up the proper distribution of conditioned air (heated or cooled) in buildings.
Manual heating or air conditioning zone dampers are mechanical doors that are manually (by hand) open or closed in order to control the amount of warm or cool air flowing to a particular room or area in a building. By totally or partially closing the damper door, the owner or occupants of the building can balance the flow of conditioned air into various areas.
But first you have to find all of the dampers - sometimes the ductwork or zone dampers are all located close to the furnace or air conditioner, but in some buildings there may be quite remote dampers. So if air flow is too much or too little in some areas of the building, in addition to checking for crushed or disconnected air ducts, look for a stealth-damper whose location may not have been immediately obvious - this means looking on all accessible sides of all surfaces of the ductwork. [Only a fool would have put a manual duct damper where you can't reach it, right?]
Because it can be tough for a new owner of an older home to even imagine, much less find where these duct air flow balancing controls are located, we include more photographs of what a manual duct air flow damper control lever might look like. At below left our red arrow shows the direction of warm air movement out of a supply plenum and into ductwork, and our blue line shows the position of the duct damper - blocking most but not all of the airflow.
Shown in another example at above right, a manual zone damper or heating duct damper or cooling duct damper is particularly valuable in balancing air flow in buildings whose HVAC system includes long duct runs to some areas and short duct runs to other areas. This damper is in the at about 80% open position.
If we take no steps to balance the air flow among building areas, when the blower fan is running, the rooms closest to the blower will receive the most air flow and more distant rooms can be difficult to heat or cool.
Photos of automatic zone damper controls wanted - Contact Us
What is an automatic duct damper and how do they work?
Automatic heating or air conditioning zone dampers are mechanical doors that open or shut under thermostatic control to provide individual area or heating or cooling zone control in buildings served by a single warm air heater or central air conditioner. In response to individual room thermostats the damper opens to permit conditioned air to flow into that room or building area when needed.
A fire damper is required in air conditioning and heating ducts in some commercial installations and possibly by local residential building codes in some jurisdictions.
A fire damper might work similarly to an automatic duct damper, but its purpose is quite different: in the event that a fire is detected in a building or in its mechanical systems, (by heat or smoke or other means of fire sensing), the fire damper closes off the air duct to avoid spreading smoke or fire rapidly through the building. The fire damper is otherwise normally "open".
A fire damper and the air ducts where it is installed would typically be located to stop fire spread between floors or other sections of a building, and it would be constructed of fire resistant materials. Think of an automatic fire damper as something like a "fire door" in a building. It closes to prevent fire spread.
Photos of automatic fire dampers & controls wanted - Contact Us
Automatic flue dampers, thermostatically controlled zone dampers, and fire dampers are compared and distinguished at DRAFT REGULATORS.
Frequently Asked Questions (FAQs) about zone dampers and airflow register booster fans used in HVAC systems
Do you do a thermostat that i can put in my room when it gets to hot it will turn a fan on to take the heat into other rooms? - K.H.
If you are asking if we can sell you a heating part the answer is no, sorry, but we do not sell anything. InspectAPedia.com provides building and environmental diagnostic and repair information. In order to absolutely assure our readers that we write and report without bias we do not sell any products nor do we have any business or financial relationships that could create such conflicts of interest.
But we can tell you what you might want to install to address your heat distribution improvement question:
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with your heat or heating distribution system - something that might change how you want to "fix" a problem of uneven heat in the building. That said If you are unable to turn down the heat in a room that is too hot (by partly closing a radiator control valve, by installing a thermostatically operated individual radiator valve, or partly closing an air supply register)
You could indeed direct warm air from one room into another that is adjoining by the following procedure:
With that set-up, when the overheated room reaches the set temperature on the new wall thermostat, that switch will turn on the electric fan that will begin moving warm air from the too-hot room to the too cool room. When the room temperature in the "too hot" room falls, the new wall thermostat will turn off the air moving fan.
Several companies make these air-moving registers and they come in a variety of sizes and colors such as
Questions & answers or comments about how to find, adjust, & use automatic or manual HVAC air duct control s or zone dampers in heating & A/C ducts in order to balance heated or cooled air flow in buildings.
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.