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  • #30 Extrol EX-30 Expansion Tank (4.4 Gallon) Product Image
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    #30 Extrol EX-30 Expansion Tank (4.4 Gallon) 102-1 #30 Extrol EX-30 Expansion Tank (4.4 Gallon)
    SKU: 102-1
    Brand: Amtrol
    (310)
    $37.56 each
    2,840
    Thu, Apr 22
    2,840
    QtyArrives
    2,840 Thu, Apr 22
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  • #15 Extrol EX-15 Expansion Tank (2 Gallon) Product Image
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    #15 Extrol EX-15 Expansion Tank (2 Gallon) 101-1 #15 Extrol EX-15 Expansion Tank (2 Gallon)
    SKU: 101-1
    Brand: Amtrol
    (75)
    $32.00 each
    380
    Thu, Apr 22
    380
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    380 Thu, Apr 22
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  • #60 Extrol EX-60 Expansion Tank (7.6 Gallon) Product Image
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    #60 Extrol EX-60 Expansion Tank (7.6 Gallon) 103-1 #60 Extrol EX-60 Expansion Tank (7.6 Gallon)
    SKU: 103-1
    Brand: Amtrol
    (43)
    $74.25 each
    86
    Thu, Apr 22
    86
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    86 Thu, Apr 22
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  • QuickStrap Expansion Tank Mounting Bracket <br>(5 Gal. Capacity) Product Image
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    QuickStrap Expansion Tank Mounting Bracket (5 Gal. Capacity) QS-U QuickStrap Expansion Tank Mounting Bracket (5 Gal. Capacity)
    SKU: QS-U
    Brand: Holdrite
    (6)
    $16.98 each
    905
    Thu, Apr 22
    905
    QtyArrives
    905 Thu, Apr 22
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  • 1/2" Pro-Pal Full Port Brass Ball Valve w/ Hi-Flow Hose Drain Product Image
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    1/2" Pro-Pal Full Port Brass Ball Valve w/ Hi-Flow Hose Drain 41672 1/2" Pro-Pal Full Port Brass Ball Valve w/ Hi-Flow Hose Drain
    Contains Lead
    SKU: 41672
    Brand: Webstone
    (12)
    $22.29 each
    276
    Thu, Apr 22
    776
    QtyArrives
    276 Thu, Apr 22
    500 Fri, Apr 23 – Mon, Apr 26
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  • 11" HydroClaw Expansion Tank Support Bracket Product Image
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    11" HydroClaw Expansion Tank Support Bracket HC11-A 11" HydroClaw Expansion Tank Support Bracket
    SKU: HC11-A
    Brand: Storm King Enterprises
    (53)
    $40.95 each
    Thu, Jul 1 – Fri, Jul 30
    Arrives
    Thu, Jul 1 – Fri, Jul 30
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  • ETX-30, Non-Potable Water Expansion Tank<br>(4.5 Gallon) Product Image
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    ETX-30, Non-Potable Water Expansion Tank (4.5 Gallon) 0066606 ETX-30, Non-Potable Water Expansion Tank (4.5 Gallon)
    SKU: 0066606
    Brand: Watts
    (18)
    $33.48 each
    3
    Thu, Apr 22
    3
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    3 Thu, Apr 22
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  • 8" HydroClaw Expansion Tank Support Bracket Product Image
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    8" HydroClaw Expansion Tank Support Bracket HC8-B 8" HydroClaw Expansion Tank Support Bracket
    SKU: HC8-B
    Brand: Storm King Enterprises
    (32)
    $30.95 each
    118
    Thu, Apr 22
    118
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    118 Thu, Apr 22
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  • Model 110 Fill-Trol<br>w/ Valve (4.4 Gallon) Product Image
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    Model 110 Fill-Trol w/ Valve (4.4 Gallon) 110-1 Model 110 Fill-Trol w/ Valve (4.4 Gallon)
    SKU: 110-1
    Brand: Amtrol
    (49)
    $74.55 each
    21
    Thu, Apr 22
    21
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    21 Thu, Apr 22
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  • Nexus Flexconsole - 1/2" x 1/2" NPT - Steel (Red) Product Image
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    Nexus Flexconsole - 1/2" x 1/2" NPT - Steel (Red) F97975 Nexus Flexconsole - 1/2" x 1/2" NPT - Steel (Red)
    Contains Lead
    SKU: F97975
    Brand: Flamco
    (10)
    $22.95 each
    61
    Thu, Apr 22
    61
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    61 Thu, Apr 22
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  • SX-30V Extrol Expansion Tank (14 Gallon) Product Image
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    SX-30V Extrol Expansion Tank (14 Gallon) 118-27 SX-30V Extrol Expansion Tank (14 Gallon)
    SKU: 118-27
    Brand: Amtrol
    (10)
    $134.99 each
    44
    Thu, Apr 22
    44
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    44 Thu, Apr 22
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  • RX-30 Radiant Extrol Expansion Tank<br>(4.4 Gallon) Product Image
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    RX-30 Radiant Extrol Expansion Tank (4.4 Gallon) 141-305 RX-30 Radiant Extrol Expansion Tank (4.4 Gallon)
    SKU: 141-305
    Brand: Amtrol
    (13)
    $68.00 each
    Wed, May 19 – Thu, Jun 17
    Arrives
    Wed, May 19 – Thu, Jun 17
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  • Model 109 Fill-Trol<br>w/ Valve (2 Gallon) Product Image
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    Model 109 Fill-Trol w/ Valve (2 Gallon) 109-1 Model 109 Fill-Trol w/ Valve (2 Gallon)
    SKU: 109-1
    Brand: Amtrol
    (19)
    $67.94 each
    22
    Thu, Apr 22
    22
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    22 Thu, Apr 22
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  • SX-40V Extrol Expansion Tank (20 Gallon) Product Image
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    SX-40V Extrol Expansion Tank (20 Gallon) 118-78 SX-40V Extrol Expansion Tank (20 Gallon)
    SKU: 118-78
    Brand: Amtrol
    (11)
    $154.99 each
    27
    Thu, Apr 22
    27
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    27 Thu, Apr 22
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  • #90 Extrol EX-90 Expansion Tank (14 Gallon) Product Image
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    #90 Extrol EX-90 Expansion Tank (14 Gallon) 112-1 #90 Extrol EX-90 Expansion Tank (14 Gallon)
    SKU: 112-1
    Brand: Amtrol
    (15)
    $137.00 each
    23
    Thu, Apr 22
    23
    QtyArrives
    23 Thu, Apr 22
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  • ETX-60, Non-Potable Water Expansion Tank<br>(6.0 Gallon) Product Image
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    ETX-60, Non-Potable Water Expansion Tank (6.0 Gallon) 0066607 ETX-60, Non-Potable Water Expansion Tank (6.0 Gallon)
    SKU: 0066607
    Brand: Watts
    (9)
    $58.79 each
    56
    Thu, Apr 22
    56
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    56 Thu, Apr 22
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  • 1/2" External NPT<br>Heating Expansion<br>Tank (4.4 Gallon) Product Image
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    1/2" External NPT Heating Expansion Tank (4.4 Gallon) TK300-30 1/2" External NPT Heating Expansion Tank (4.4 Gallon)
    SKU: TK300-30
    Brand: Resideo
    (6)
    $46.94 each
    133
    Thu, Apr 22
    133
    QtyArrives
    133 Thu, Apr 22
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  • SX-60V Extrol Expansion Tank (32 Gallon) Product Image
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    SX-60V Extrol Expansion Tank (32 Gallon) 118-79 SX-60V Extrol Expansion Tank (32 Gallon)
    SKU: 118-79
    Brand: Amtrol
    (2)
    $229.98 each
    17
    Thu, Apr 22
    17
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    17 Thu, Apr 22
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  • ETX-15, Non-Potable Water Expansion Tank<br>(2.1 Gallon) Product Image
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    ETX-15, Non-Potable Water Expansion Tank (2.1 Gallon) 0066605 ETX-15, Non-Potable Water Expansion Tank (2.1 Gallon)
    SKU: 0066605
    Brand: Watts
    (2)
    $29.75 each
    53
    Thu, Apr 22
    53
    QtyArrives
    53 Thu, Apr 22
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  • RX-15 Radiant Extrol Expansion Tank (2 Gallon) Product Image
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    RX-15 Radiant Extrol Expansion Tank (2 Gallon) 140-705 RX-15 Radiant Extrol Expansion Tank (2 Gallon)
    SKU: 140-705
    Brand: Amtrol
    (7)
    $53.59 each
    10
    Thu, Apr 22
    10
    QtyArrives
    10 Thu, Apr 22
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  • 1/2" Pro-Pal Full Port Brass Ball Valve w/ Hi-Flow Hose Drain - FIP x FIP (600 WOG) Product Image
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    1/2" Pro-Pal Full Port Brass Ball Valve w/ Hi-Flow Hose Drain - FIP x FIP (600 WOG) H-44672 1/2" Pro-Pal Full Port Brass Ball Valve w/ Hi-Flow Hose Drain - FIP x FIP (600 WOG)
    SKU: H-44672
    Brand: Webstone
    (1)
    $22.99 each
    135
    Thu, Apr 22
    149
    QtyArrives
    135 Thu, Apr 22
    14 Fri, Apr 23 – Mon, Apr 26
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  • Fill Control Valve Product Image
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    Fill Control Valve 109-15 Fill Control Valve
    SKU: 109-15
    Brand: Amtrol
    (9)
    $40.00 each
    6
    Thu, Apr 22
    6
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    6 Thu, Apr 22
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  • RBFF, 1/2" Residential Boiler Fill Fitting Product Image
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    RBFF, 1/2" Residential Boiler Fill Fitting 0386466 RBFF, 1/2" Residential Boiler Fill Fitting
    SKU: 0386466
    Brand: Watts
    (4)
    $65.00 each
    14
    Thu, Apr 22
    14
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    14 Thu, Apr 22
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  • Model 110 Fill-Trol<br>Tank Only (4.4 Gallon) Product Image
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    Model 110 Fill-Trol Tank Only (4.4 Gallon) 110-002 Model 110 Fill-Trol Tank Only (4.4 Gallon)
    SKU: 110-002
    Brand: Amtrol
    (12)
    $60.53 each
    21
    Thu, Apr 22
    21
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    21 Thu, Apr 22
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FAQs, Manuals & Videos

Resources

Videos

Articles

  • An expansion tank is designed to relieve pressure in both a potable water and closed heating system. An expansion tank ensures a constant pressure is maintained within the pipes so they do not get damaged from excess pressure.

    An expansion tank has two parts which are divided by a rubber diaphragm. The top portion of the tank is connected to the hot water system and is filled with water. The bottom portion is filled with air set at approximately 12 psi. As the hot water system is turned on or off, pressure increases. As pressure increases, the diaphragm in the expansion tank is pushed down. This compresses the air in the tank, creating more space for excess water to enter. This relieves excess pressure in the system and prevents pipes in the system from being damaged.

    In the event that the diaphragm fails, the tank will completely fill with water. If this occurs, the tank must be replaced immediately. To check if the expansion tank is working properly, simply place your hand on the tank and feel its temperature. The top portion of the tank should feel warm to the touch, and the bottom portion of the tank should be room temperature. If the entire tank is warm, it is likely that the tank has completely filled with hot water.

    Expansion tanks have capacities ranging from 2 gallons to several hundred gallons. To determine the size needed for your system, use the Expansion Tank Sizing Calculator.

    We offer a wide selection of Amtrol, Watts, and Bell & Gossett expansion tanks to suit all of your plumbing and heating needs.

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