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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
    (275)
    $34.49 each
    4,897
    Thu, Oct 1
    4,897
    QtyArrives
    4,897 Thu, Oct 1
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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
    (70)
    $29.99 each
    556
    Thu, Oct 1
    556
    QtyArrives
    556 Thu, Oct 1
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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
    (38)
    $67.69 each
    366
    Thu, Oct 1
    366
    QtyArrives
    366 Thu, Oct 1
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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
    1,149
    Thu, Oct 1
    1,149
    QtyArrives
    1,149 Thu, Oct 1
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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
    551
    Thu, Oct 1
    1,051
    QtyArrives
    551 Thu, Oct 1
    500 Fri, Oct 2 – Mon, Oct 5
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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
    (51)
    $40.95 each
    289
    Thu, Oct 1
    289
    QtyArrives
    289 Thu, Oct 1
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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
    (10)
    $22.95 each
    64
    Thu, Oct 1
    64
    QtyArrives
    64 Thu, Oct 1
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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
    210
    Thu, Oct 1
    210
    QtyArrives
    210 Thu, Oct 1
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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
    (46)
    $78.49 each
    94
    Thu, Oct 1
    94
    QtyArrives
    94 Thu, Oct 1
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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
    Thu, Oct 1
    72
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    72 Thu, Oct 1
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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
    (11)
    $64.99 each
    85
    Thu, Oct 1
    85
    QtyArrives
    85 Thu, Oct 1
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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
    188
    Thu, Oct 1
    188
    QtyArrives
    188 Thu, Oct 1
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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
    67
    Thu, Oct 1
    67
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    67 Thu, Oct 1
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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
    84
    Thu, Oct 1
    84
    QtyArrives
    84 Thu, Oct 1
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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
    128
    Thu, Oct 1
    128
    QtyArrives
    128 Thu, Oct 1
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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
    24
    Thu, Oct 1
    24
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    24 Thu, Oct 1
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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
    (4)
    $45.56 each
    87
    Thu, Oct 1
    87
    QtyArrives
    87 Thu, Oct 1
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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
    (6)
    $55.99 each
    87
    Thu, Oct 1
    87
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    87 Thu, Oct 1
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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
    Thu, Oct 22 – Thu, Oct 29
    Arrives
    Thu, Oct 22 – Thu, Oct 29
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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
    78
    Thu, Oct 1
    220
    QtyArrives
    78 Thu, Oct 1
    142 Fri, Oct 2 – Mon, Oct 5
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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
    Mon, Dec 14 – Mon, Jan 11
    Arrives
    Mon, Dec 14 – Mon, Jan 11
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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
    61
    Thu, Oct 1
    61
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    61 Thu, Oct 1
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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
    (11)
    $67.49 each
    12
    Thu, Oct 1
    12
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    12 Thu, Oct 1
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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
    (1)
    $28.34 each
    82
    Thu, Oct 1
    82
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    82 Thu, Oct 1
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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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