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Hot water heating system air scoops, air separators & air scoops: what they do, where they belong, how they work to prevent noise and loss of heat in hydronic heating systems. In this heating system article series we explain how to Identify the parts & components of Hot Water Heating Boilers and hot water heating systems including oil burners and their parts, boiler parts, hot water baseboard and its parts, hot water radiators, and hot water convector units and their parts and controls. Each simple definition includes links to detailed articles discussing how to identify, inspect, diagnose, and repair each component of the heating system.

Also see Air bleeders that work with air scoops to remove un-wanted air from hydronic (hot water) heating systems. Air in heating distribution piping, boilers, radiators, can prevent hot water circulation and thus stop heat from being delivered to the occupied space. If your heating system is having trouble with noise or cold baseboards or radiators, see AIRBOUND HEAT SYSTEM REPAIRS.

See BOILER CONTROLS & SWITCHES and BOILER COMPONENTS & PARTS for a description of the key heating boiler operating controls and switches. If your building uses steam heat see STEAM HEATING SYSTEMS. If your building uses warm air heat see FURNACE CONTROLS & SWITCHES

This website answers most questions about central hot water heating system troubleshooting, inspection, diagnosis, and repairs. We describe how to inspect residential heating systems to inform home owners, buyers, and home inspectors of common heating system defects.

Our discussion of radiators or baseboards that do not get hot when they should includes these key sections:

1. Air Bleeder Valves - a Guide to Air Bleeder Valves for Hot Water Heating Systems: Radiators, Baseboards, Convectors - how to find and use manual and automatic air bleeders to fix noisy gurgling heating pipes or an airbound heating system.
2. Air Scoops, Air Separators, Air Purgers: Since on many hot water heating systems a key air bleeding or air vent point is at the air scoop or air separator closer to the boiler, see Air Scoops Purgers Separators. Air purges for steam heating systems are discussed separately at Steam Vents. Also see AIRBOUND HEAT SYSTEM REPAIRS and the two procedures listed just below.
3. Airbound Heating System Relief Procedure #1 Using Water Feeder & Boiler Drain - how to use built-in controls and valves to force air out an air-bound heating system whose radiators, convectors, or baseboards are not warming up
4. Airbound Heating System Relief Procedure #2 Using a Pony Pump - how to use a portable pump, short sections of garden hose, and heating system valves to force air out an air-bound heating system whose radiators, convectors, or baseboards are not warming up.
5. Water Feeder Valves, Hydronic - a defective automatic water feeder valve on a hot water heating boiler can result in too little starting water pressure in the system - radiators on upper floors may fail to receive heat. On a steam heating boiler a defective automatic water feed valve can cause the heating system to shut down completely or can lead to boiler damage or even unsafe conditions. At BOILER PRESSURE & TEMPERATURE SETTINGS we discuss the pressures needed for hydronic or hot water heating systems - a taller building needs higher starting (cold) pressure in the heating boiler. At Water Feeder Valves, Hydronic we discuss problems with water feeder valves that also control water pressure in the boiler and we explain how to adjust the water feeder valve and thus boiler water pressure. If your heating system uses a steam boiler, see Water Feeder Valves, Steam.

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Air Scoops, Air Separators, Air Purgers on Hot Water Heating Systems Eliminate Air and Noise & Prevent Air Bound Loss of Heat

Hot water heating systems, whether using baseboards, convectors, radiators, or even radiant tubing, can be noisy if there is air circulating in the system. Worse, as we discuss at AIRBOUND HEAT SYSTEM REPAIRS, if the amount of air is excessive, the circulator pump(s) may not be able to circulate hot water at all and portions of the heating system (radiators, baseboards etc) may just stay cold.

Air is dissolved in cold water in any hydronic heating system. When we heat the water, some of that air returns to a gas form as air bubbles that cause noise heard at circulator pumps, in the hot water piping, or in radiators or baseboards. Air might also enter a hot water heating system due to a leak in piping that lets water out when the system is hot and lets air in when the heating system is cold. Of course there are other causes of noise in heating systems, but air in the piping is perhaps the most common noise complaint.

Taco™, a manufacturer of heating system components and controls, provides this clear explanation of the function of the air scoop or air separator on a hot water heating system:

The Taco Air Scoop® is specifically designed to provide a noiseless, air-free hydronic heating, cooling or combination system, by efficiently separating out the air from the water in any of these systems.

Air being lighter than water, it travels along the upper portion of a horizontal pipe in low velocity hydronic systems. As the air and water enter the Air Scoop their velocity decreases, permitting the air bubbles to be scooped up by the baffle and directed to the top of the chamber.

The air reaching the top of the air scoop is either immediately vented through a Hy-Vent® or it moves into a conventional plain steel expansion tank, if used. Should the air completely fill the plain steel tank and back down into the Air Scoop, the excess will be removed by the Hy-Vent without disturbing the operation of the system.

Air Troubles on Hot Water Heating Systems & the Air Scoop

Install the air scoop in the right direction: Notice the arrow cast into the body of the Taco™ air scoop (photo above, sketch at left) and on the sketch of the Sparco™ air purger below?

Make sure that your air scoop is installed in the right direction, consistent with the intended flow of hot water in the heat distribution piping. Installing the device backwards, a common error on both air scoops and flow-check valves, is likely to prevent it from working.

If a check valve is installed, make sure it too is installed in the right direction. Your system may not use a check valve if its circulator pump incorporates an internal flow check valve (IFC).

If your hot water heating system is noisy, is not automatically purging air, or is air bound, in addition to purging un-wanted air manually and finding and fixing any leaks that are letting air into the heating distribution piping or boiler, be sure that your air scoop is properly installed.

Make sure the air vent is working: Even if the air scoop is properly installed and located (see Taco's sketch, above), if the "Hy Vent" or "Float Vent" or automatic air purge valve (these are all synonyms from different manufacturers) is not working the system may not successfully purge air. See Air Bleeder Valves, and see AIRBOUND HEAT SYSTEM REPAIRS.

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At above left we illustrate another air purger manufactured by Sparco.

At above right we include a sketch of Bell & Gosset's inline air separator (IAS). The B&G inline air separator has the same function as the air scoops discussed above, but its internal workings are a bit different. Here is B&G's explanation of how their IAS works:

"IAS stands for Inline Air Separator. It has two chambers, and it's a bit wider than the pipe it serves. We separated the two chambers with an orifice, and therein lies the secret to the IAS's great performance. "An orifice is a hole that's a bit smaller than the chamber itself. Air-laden water flows down the pipe and enters the "wide space in the road" - the IAS. Naturally, as the water widens out in the IAS, it also slows down. That slowing motion releases the air bubbles in the same way a slowing river current releases floating debris.

"The air bubbles quickly float to the top of the first chamber and get trapped by the wall of iron that makes up the orifice and flows to the radiators. Since the IAS snatches the air out of the flow just as it leaves the boiler; the air doesn't get a chance to create problems out in the system."Once captured, the IAS vents the air out of the system through an automatic air vent, which you'll install in the IAS's top tapping. If you're using a plain steel compression tank, the IAS will pass the air up into the tank." - Bell & Gossett

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BOILERS, HEATING
  BACKDRAFTING HEATING EQUIPMENT
  BOILER COMPONENTS & PARTS
  BOILER CONTROLS & SWITCHES
  Air Bleeder Valves
  Air-bound boilers & radiators
  Air Scoops Purgers Separators
  AQUASTAT CONTROL Functions
  BACKDRAFTING HEATING EQUIPMENT
  BANGING HEATING PIPE NOISES
  CAD CELL RELAY SWITCH
  Check Valves Flow Control Valves Flo Control
  Chemical treatments, Boiler
  Circulator Pumps & Relays
  DIAGNOSE & FIX BOILER
  DRAFT REGULATORS, BAROMETRIC DAMPERS
  ELECTRIC MOTOR OVERLOAD RESET SWITCH
  ELECTRICAL POWER SWITCH FOR HEAT
  Expansion Tanks
  FIRE SAFETY CONTROLS
  Gauges on Heating Equipment
  Limit Switches, Boilers
  Low Water Cutoff Valves, Boilers
  MIXING / ANTI-SCALD VALVES
  OIL LINE SAFETY VALVES
  Pressure Gauges, Boilers
  Pressure & Temperature Settings, Controls
  RELIEF VALVES - TP VALVES
  Reset Switch - Primary Control
  Reset Switch - electric motors
  SPILL SWITCHES
  STACK RELAYS
  THERMOSTATS, HEATING / COOLING
  Water Feeder Valves, Hydronic Boiler
  Zone Valves

BOILER LEAKS CORROSION STAINS
BOILER LEAKS, HOW TO LOCATE
BOILER NOISE SMOKE ODORS
BOILER OPERATING PROBLEMS
BOILER OPERATION DETAILS
BOILER PRESSURE & TEMPERATURE SETTINGS

• Bell & Gossett Air Separators and other heating system components, 8200 N. Austin Ave., Morton Grove IL 60053, USA - Tel 847 966-3700 Fax 847 965-8379 . Air separators are discussed by B&G at http://www.bellgossett.com/homeowners/BG-airseparator.asp
• Taco air scoops and other heating system components & controls: Taco Inc., 1160 Cranston Street, Cranston, RI 02920 / (401) 942-8000 / Fax (401) 942-2360 Taco (Canada) Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3 / (905) 564-9422 / Fax (905) 564-9436 www.taco-hvac.com
  Taco also has some helpful FAQs that are useful in diagnosing circulator problems - see http://www.taco-hvac.com/en/faq.html#
• Sparco air purgers, air scoops, and other heating system components & controls:

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

• Carbon Monoxide Gas Toxicity, exposure limits, poisoning symptoms, and inspecting buildings for CO hazards
• DUST CONTAMINATION FROM HVAC? An Investigation of Indoor Dust Debris Blamed on a Heating/Cooling System Reveals Carpet Dust
• Fuel Oil & Oil Heating Magazine, 3621 Hill Rd., Parsippany, NJ 07054, 973-331-9545
• Goodman Furnace High Temperature Plastic Vent HTPV safety recall US CPSC notice
• Home Heating System Should Be Checked [for proper venting and for CO Carbon Monoxide Hazards - DJF]
• Inspection Procedures for Oil-Fired Heating Systems Detailed step by step approaches for inspecting complex systems]
• Lennox Pulse Furnace Safety Inspection/Warranty Program: Carbon Monoxide Warning
• Oil Tanks - The Oil Storage Tank Information Website: Buried or Above Ground Oil Tank Inspection, Testing, Cleanup, Abandonment of Oil Tanks
• Oil Tanks Above Ground, UL Standards, guidance for home owners, buyers, and inspectors
• Plastic Heating Vent Pipe & Other Heating Safety Recall Notices
• Weil McLain Model GV Gas Boiler/gas valve CPSC recall/repair
• Domestic and Commercial Oil Burners, Charles H. Burkhardt, McGraw Hill Book Company, New York 3rd Ed 1969.
• National Fuel Gas Code (Z223.1) $16.00 and National Fuel Gas Code Handbook (Z223.2) $47.00 American Gas Association (A.G.A.), 1515 Wilson Boulevard, Arlington, VA 22209 also available from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269. Fundamentals of Gas Appliance Venting and Ventilation, 1985, American Gas Association Laboratories, Engineering Services Department. American Gas Association, 1515 Wilson Boulevard, Arlington, VA 22209. Catalog #XHO585. Reprinted 1989.
• The Steam Book, 1984, Training and Education Department, Fluid Handling Division, ITT [probably out of print, possibly available from several home inspection supply companies] Fuel Oil and Oil Heat Magazine, October 1990, offers an update,
• Principles of Steam Heating, $13.25 includes postage. Fuel oil & Oil Heat Magazine, 389 Passaic Ave., Fairfield, NJ 07004.
• The Lost Art of Steam Heating, Dan Holohan, 516-579-3046 FAX
• Principles of Steam Heating, Dan Holohan, technical editor of Fuel Oil and Oil Heat magazine, 389 Passaic Ave., Fairfield, NJ 07004 ($12.+1.25 postage/handling).
• "Residential Steam Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
• "Residential Hydronic (circulating hot water) Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
• "Warm Air Heating Systems". Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
• Heating, Ventilating, and Air Conditioning Volume I, Heating Fundamentals,
• Boilers, Boiler Conversions, James E. Brumbaugh, ISBN 0-672-23389-4 (v. 1) Volume II, Oil, Gas, and Coal Burners, Controls, Ducts, Piping, Valves, James E. Brumbaugh, ISBN 0-672-23390-7 (v. 2) Volume III, Radiant Heating, Water Heaters, Ventilation, Air Conditioning, Heat Pumps, Air Cleaners, James E. Brumbaugh, ISBN 0-672-23383-5 (v. 3) or ISBN 0-672-23380-0 (set) Special Sales Director, Macmillan Publishing Co., 866 Third Ave., New York, NY 10022. Macmillan Publishing Co., NY
• Installation Guide for Residential Hydronic Heating Systems
• Installation Guide #200, The Hydronics Institute, 35 Russo Place, Berkeley Heights, NJ 07922
• The ABC's of Retention Head Oil Burners, National Association of Oil Heat Service Managers, TM 115, National Old Timers' Association of the Energy Industry, PO Box 168, Mineola, NY 11501. (Excellent tips on spotting problems on oil-fired heating equipment. Booklet.)
• Links to our list of additional information on heating system inspection, repair, maintenance
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