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  • #30 Extrol Expansion Tank (4.4 Gallon) Product Image
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    #30 Extrol Expansion Tank (4.4 Gallon) 102-1 #30 Extrol Expansion Tank (4.4 Gallon)
    SKU: 102-1
    Brand: Amtrol
    (272)
    $34.49 each
    1,995
    Wed, Jul 15
    1,995
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    1,995 Wed, Jul 15
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  • #15 Extrol Expansion Tank (2 Gallon) Product Image
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    #15 Extrol Expansion Tank (2 Gallon) 101-1 #15 Extrol Expansion Tank (2 Gallon)
    SKU: 101-1
    Brand: Amtrol
    (69)
    $29.99 each
    698
    Wed, Jul 15
    698
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    698 Wed, Jul 15
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  • #60 Extrol Expansion Tank (7.6 Gallon) Product Image
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    #60 Extrol Expansion Tank (7.6 Gallon) 103-1 #60 Extrol Expansion Tank (7.6 Gallon)
    SKU: 103-1
    Brand: Amtrol
    (36)
    $67.69 each
    432
    Wed, Jul 15
    432
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    432 Wed, Jul 15
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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
    (3)
    $14.99 each
    1,695
    Wed, Jul 15
    1,695
    QtyArrives
    1,695 Wed, Jul 15
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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
    (10)
    $22.29 each
    234
    Wed, Jul 15
    734
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    234 Wed, Jul 15
    500 Fri, Jul 17 – Mon, Jul 20
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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
    (50)
    $40.95 each
    110
    Wed, Jul 15
    110
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    110 Wed, Jul 15
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  • Flexconsole - 1/2" x 1/2" NPT - Steel (Red) Product Image
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    Flexconsole - 1/2" x 1/2" NPT - Steel (Red) 97975 Flexconsole - 1/2" x 1/2" NPT - Steel (Red)
    Contains Lead
    SKU: 97975
    Brand: Flamco
    (9)
    $22.95 each
    60
    Wed, Jul 15
    60
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    60 Wed, Jul 15
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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
    (29)
    $30.95 each
    77
    Wed, Jul 15
    77
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    77 Wed, Jul 15
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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
    (45)
    $78.49 each
    43
    Wed, Jul 15
    43
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    43 Wed, Jul 15
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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)
    $135.99 each
    72
    Wed, Jul 15
    72
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    72 Wed, Jul 15
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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
    (10)
    $64.99 each
    35
    Wed, Jul 15
    35
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    35 Wed, Jul 15
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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
    (18)
    $67.99 each
    42
    Wed, Jul 15
    42
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    42 Wed, Jul 15
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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
    (14)
    $31.89 each
    21
    Wed, Jul 15
    21
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    21 Wed, Jul 15
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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)
    $155.99 each
    31
    Wed, Jul 15
    31
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    31 Wed, Jul 15
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  • #90 Extrol Expansion Tank (14 Gallon) Product Image
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    #90 Extrol Expansion Tank (14 Gallon) 112-1 #90 Extrol Expansion Tank (14 Gallon)
    SKU: 112-1
    Brand: Amtrol
    (11)
    $114.99 each
    96
    Wed, Jul 15
    96
    QtyArrives
    96 Wed, Jul 15
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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)
    $232.99 each
    36
    Wed, Jul 15
    36
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    36 Wed, Jul 15
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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: Honeywell-Sparco
    (4)
    $42.45 each
    36
    Wed, Jul 15
    48
    QtyArrives
    36 Wed, Jul 15
    12 Thu, Jul 16
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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
    $22.99 each
    66
    Wed, Jul 15
    269
    QtyArrives
    66 Wed, Jul 15
    203 Fri, Jul 17 – Mon, Jul 20
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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)
    $59.99 each
    16
    Wed, Jul 15
    16
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    16 Wed, Jul 15
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  • Flexconsole - 3/4" x 1/2" NPT - Stainless Steel (White) Product Image
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    Flexconsole - 3/4" x 1/2" NPT - Stainless Steel (White) 97976-FLAMCO Flexconsole - 3/4" x 1/2" NPT - Stainless Steel (White)
    SKU: 97976-FLAMCO
    Brand: Flamco
    $66.95 each
    32
    Wed, Jul 15
    32
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    32 Wed, Jul 15
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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
    (5)
    $55.99 each
    Mon, Jul 20 – Wed, Jul 22
    Arrives
    Mon, Jul 20 – Wed, Jul 22
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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)
    $37.99 each
    12
    Wed, Jul 15
    12
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    12 Wed, Jul 15
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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)
    $66.99 each
    1
    Wed, Jul 15
    1
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    1 Wed, Jul 15
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  • Model 109 Fill-Trol, <br>Tank Only (2 Gallon) Product Image
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    Model 109 Fill-Trol, Tank Only (2 Gallon) 109-133 Model 109 Fill-Trol, Tank Only (2 Gallon)
    SKU: 109-133
    Brand: Amtrol
    (13)
    $57.99 each
    2
    Wed, Jul 15
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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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