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Copyright © 2014 by Thrush Co Inc 

 

 

4.2  Operation 
 

Heating/cooling system efficiency and component life is greatly dependent on water 
quality. Air and dirt particles can cause pump cavitation, corrosion and increased 
component wear. In a closed loop system, the 

Aar-O-Vent 

eliminates air bubbles, 

entrained air and dirt particles quickly and easily. 
 

Air Elimination: 
 
Thrush Co. offers the 

Aar-O-Vent

 in “Air Only”, “Dirt Only” and combination units “Air 

and Dirt”. The “Air Only” and “Air & Dirt” units are the only models that utilize the 
Thrush Model 720 air elimination device, air vent. They also have extra space in the 
top of the vessel for the collection of air. Outlined below is operational information on 
the air elimination feature of the 

Aar-O-Vent

. Use Figure 4-2 for reference (“Air and 

Dirt” model shown).  
 

  Large air bubbles in the system water enter the 

Aar-O-Vent

 and collide with the 

coalescing medium. They quickly rise to the top of the vessel and into the air 
elimination device. 

 

  Micro bubbles coalesce and form larger bubbles. The larger bubbles then rise to 

the top of the vessel and into the air elimination device.  

 

  Entrained air is pulled out of solution and forms micro bubbles. The micro bubbles 

coalesce forming larger bubbles. The larger bubbles rise to the top of the vessel 
and into the air elimination device.  

 

  As air bubbles collect at the top of the vessel they create an air pocket. This 

pocket of air pushes the water level down inside the vessel. As the water level 
drops, the float inside of the air elimination device also drops releasing the air to 
atmosphere.  

 

  The air elimination device releases air as fast as it can be separated. It will not 

allow air back into the system, even if a vacuum occurs. 

 

  Once the air has been released, the water level will rise inside the vessel. This 

causes the float to rise and close the air elimination device.  
 

This cycle will continue as new water is introduced into the system piping. With each 
pass of system water the 

Aar-O-Vent 

will eventually eliminate up to 99.7% of 

dissolved oxygen content in the system piping.  

 

The 

Aar-O-Vent

 is not designed to be used as a make-up water inlet point. Using 

any of the connections for make-up water would impede proper operation and 

void the warranty.  

 
 

Thrush Co. 

Manual #9636-1230 

Summary of Contents for AAR-O-VENT TAHF

Page 1: ...gh Performance Air Dirt Separators Manual 9636 1230 Rev B 340 West 8th Street Peru IN 46970 PH 765 472 3351 FX 765 472 3968 www thrushco com Copyright 2014 by Thrush Co Inc U S PATENT 8 177 975 Operation Maintenance Manual ...

Page 2: ......

Page 3: ...E OR TRANSMIT THIS DOCUMENT OR THE INFORMATION CONTAINED HEREIN IN WHOLE OR IN PART OR TO PERMIT OTHERS TO DO SO FOR ANY PURPOSE WITHOUT FIRST OBTAINING THE EXPRESS WRITTEN PERMISSION FROM THRUSH CO RECIPIENT FURTHER AGREES TO SURRENDER THIS DOCUMENT UPON REQUEST BY THRUSH CO Section No Description Page No 1 General Product Information 1 2 Safety Information Warnings 2 3 Component Identification a...

Page 4: ...rt Only and combination Air Dirt Separator Air Separator TASF Standard Velocity Air Separator TAHF High Velocity Air Separator Dirt Separator TDSR Standard Velocity Dirt Separator with Removable Cover TDHR High Velocity Dirt Separator with Removable Cover TDSF Standard Velocity Dirt Separator with Fixed Cover TDHF High Velocity Dirt Separator with Fixed Cover Air Dirt Separator TBSR Standard Veloc...

Page 5: ...Aar O Vent the bundle can be quite heavy It is recommended that supports be used when removing the head and bundle Once all bolts have been removed from the head the head and bundle are free to drop Risk of severe personal injury and or property damage may occur if the bundle and head are not supported 5 and larger Aar O Vents have lift lugs to aid in lifting and locating the unit The lift lugs ar...

Page 6: ...f a Thrush Co Aar O Vent This manual provides information for multiple Aar O Vent models All the components listed have the same functional purpose in each model 2 4 SIGHT GLASS ASME NAMEPLATE REMOVABLE HEAD BLOW DOWN VALVE 2 GAUGE TAP SKIM VALVE AIR ELIMINATOR COALESCING MEDIUM NOT SHOWN OPTIONAL EQUIPMENT LIFT LUGS 2 5 LARGER Figure 3 1 Components Thrush Co Manual 9636 1230 Thrush Co Manual 9636...

Page 7: ...bles and or entrained air from the water by means of an air eliminator or blow down valve This patented design resists corrosion and can be easily cleaned Figure 3 2 Coalescing Medium 3 1 2 Sight Glass Optional One of the optional features offered with each Aar O Vent is sight glasses Sight glasses allow the user to periodically check the coalescing medium for signs of dirt build up Figure 3 3 Sig...

Page 8: ...NCE REQUIRED TO REMOVE BUNDLE Figure 3 4 Removable Head Detail Depending on the size of Aar O Vent the bundle can be quite heavy It is recommended that supports be used when removing the head and bundle Once all bolts have been removed from the head the head and bundle are free to drop Risk of severe personal injury and or property damage may occur if the bundle and head are not supported 3 1 4 Th...

Page 9: ... 8 NPT LEVER ASSEMBLY AIR COLLECTION CHAMBER LID CONTROL ASSEMBLY Figure 3 5 Air Vent Air Eliminator Operation The air eliminator is used on the Aar O Vent to remove unwanted air that could reduce system performance increase operational cost and support the damaging effects of corrosion The collection of air in the body of the air eliminator causes the float to drop allowing the air to be vented t...

Page 10: ... and spaced pipe supports hangers should be used to prevent damage or strain on the system piping 4 An Aar O Vent should be installed in a piping system at its lowest point of solubility Typically the point of highest temperature and lowest pressure is the ideal location 5 When placing the Aar O Vent with removable head in the system piping be aware of the clearance required for bundle removal and...

Page 11: ... DRAIN BLOW DOWN VALVE SKIM VALVE LIFT LUGS 2 5 LARGER Figure 4 1 Typical Piping Diagram 1 Connect the supply source to one connection of the Aar O Vent 2 Connect suction piping of the pump to the other connection of the Aar O Vent 3 The air vent the blow down valve and the skim valve should be run to an adequate drain 4 Once all connections are made allow the system to completely fill with water ...

Page 12: ...r bubbles then rise to the top of the vessel and into the air elimination device Entrained air is pulled out of solution and forms micro bubbles The micro bubbles coalesce forming larger bubbles The larger bubbles rise to the top of the vessel and into the air elimination device As air bubbles collect at the top of the vessel they create an air pocket This pocket of air pushes the water level down...

Page 13: ...BLES COALESCE FORMING LARGER BUBBLES RELEASED AIR AIR COLLECTS AT THE TOP OF THE VESSEL LOWERING THE WATER LEVEL WHICH CAUSES THE FLOAT INSIDE THE AIR VENT TO DROP AND RELEASE THE AIR FLOAT COALESCING MEDIUM AIR ELIMINATOR SKIM VALVE Figure 4 2 Operation Air Elimination Thrush Co Manual 9636 1230 ...

Page 14: ... of the flow path and to the bottom of the vessel Dirt particles will continue to collect at the bottom of the vessel until they are flushed out through the blow down valve Floating debris can be flushed out by opening the skim valve located on the top of the vessel Should the need to clean the coalescing medium arise the removable head provides ease of removal and cleaning Depending on the size o...

Page 15: ... DIRT PARTICLES COALESCING MEDIUM SEPARATES THE DIRT PARTICLES FROM THE SYSTEM WATER DIRT PARTICLES FALL OUT OF THE FLOW PATH AND COLLECT IN THE BOTTOM OF THE VESSEL BLOW DOWN VALVE DIRT PARTICLES FLUSHED OUT SKIM VALVE Figure 4 3 Operation Dirt Elimination Thrush Co Manual 9636 1230 ...

Page 16: ...ction allows for ease of cleaning A new gasket should be installed upon reassembly of the unit Tighten all bolts in a criss cross fashion properly torqued See chart below Depending on the size of Aar O Vent the head and bundle can be quite heavy It is recommended that supports be used when removing the head bundle Once all bolts have been removed from the head the head and bundle are free to drop ...

Page 17: ...omer service department Thrush Co Inc PO Box 228 340 West 8th Street Peru IN 46970 Attention Customer Service Group Phone 765 472 3351 800 755 8110 Fax 765 472 3968 E mail customerservice thrushco com When calling or writing to place a parts order to your representative it is recommended to have the following items for reference 1 Part number s 2 Description of product s 3 Quantity required 4 Nati...

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