Air scoop air purger air separator (C) Daniel FriedmanHeating Boiler Air Scoops
Bulk Air Separators & Air Purgers

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Hot water heating system air scoops, air separators & air scoops:

What a bulk air eliminator or "air scoop"does, where they belong, how they work to prevent noise and loss of heat in hydronic heating systems.

Automatic air removal from hot water heating systems avoids air-bound boilers, baseboards, radiators, radiant heat loops. What is the function of the air scoop automatic air purger on heating systems? Common manufacturers of bulk air eliminators include American air purgers, Taco air scoops, Sparco air purgers, Bell & Gossett inline air separators

This article series answers most questions about central hot water 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.

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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

Taco brand air scoop (C) Taco D FriedmanHot 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 REPAIR by WATER FEED VALVE, 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.

Also see AIR BLEEDER VALVES 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,

For a complete list of diagnostic articles for radiators or baseboards that do not get hot when they should includes

Air Troubles on Hot Water Heating Systems & the Air Scoop

Taco air scoop installation sketch (C) Taco - D FriedmanInstall 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?

[Click to enlarge any image]

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.


Sparco air purger (C) Sparco D Friedman Sparco air purger (C) Sparco D Friedman

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

Research on bulk air eliminators


Continue reading at AIR-BOUND HEATING SYSTEMS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


Or see DISSOLVED OXYGEN DAMAGE CONTROL - use of bulk air eliminators on hydronic heating systems helps avoid damage from dissolved oxygen

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AIR SCOOPS SEPARATORS PURGERS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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