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  • THERM-X-TROL ST-5 Expansion Tank Product Image
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    THERM-X-TROL ST-5 Expansion Tank 140N43 THERM-X-TROL ST-5 Expansion Tank
    SKU: 140N43
    Brand: Amtrol
    (56)
    $40.99 each
    158
    Fri, Jul 17
    158
    QtyArrives
    158 Fri, Jul 17
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  • THERM-X-TROL ST-12 Expansion Tank Product Image
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    THERM-X-TROL ST-12 Expansion Tank 141N43 THERM-X-TROL ST-12 Expansion Tank
    SKU: 141N43
    Brand: Amtrol
    (42)
    $55.99 each
    36
    Fri, Jul 17
    36
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    36 Fri, Jul 17
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  • PLT-5, 2.1 Gallon Potable<br>Water Expansion Tank Product Image
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    PLT-5, 2.1 Gallon Potable Water Expansion Tank 0067370 PLT-5, 2.1 Gallon Potable Water Expansion Tank
    SKU: 0067370
    Brand: Watts
    (10)
    $36.59 each
    168
    Fri, Jul 17
    168
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    168 Fri, Jul 17
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  • WX-350 (151S1)<br>119 Gal. WELL-X-TROL Well Tank Product Image
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    WX-350 (151S1) 119 Gal. WELL-X-TROL Well Tank WX-350 WX-350 (151S1) 119 Gal. WELL-X-TROL Well Tank
    SKU: WX-350
    Brand: Amtrol
    (17)
    $1,049.99 each
    45
    Wed, Jul 22 – Fri, Jul 24
    45
    QtyArrives
    45 Wed, Jul 22 – Fri, Jul 24
    Questions? Call 1-888-757-4774
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  • WX-250 (145S1), 44 Gal. WELL-X-TROL Well Tank Product Image
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    WX-250 (145S1), 44 Gal. WELL-X-TROL Well Tank WX-250 WX-250 (145S1), 44 Gal. WELL-X-TROL Well Tank
    SKU: WX-250
    Brand: Amtrol
    (77)
    $495.99 each
    209
    Fri, Jul 17
    209
    QtyArrives
    209 Fri, Jul 17
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  • WX-302 (150S1), 86 Gal. WELL-X-TROL Well Tank Product Image
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    WX-302 (150S1), 86 Gal. WELL-X-TROL Well Tank WX-302 WX-302 (150S1), 86 Gal. WELL-X-TROL Well Tank
    SKU: WX-302
    Brand: Amtrol
    (28)
    $734.99 each
    38
    Wed, Jul 22 – Fri, Jul 24
    38
    QtyArrives
    38 Wed, Jul 22 – Fri, Jul 24
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  • WX-203 (146S30), 32 Gal. WELL-X-TROL Well Tank Product Image
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    WX-203 (146S30), 32 Gal. WELL-X-TROL Well Tank WX-203 WX-203 (146S30), 32 Gal. WELL-X-TROL Well Tank
    SKU: WX-203
    Brand: Amtrol
    (76)
    $389.99 each
    30
    Fri, Jul 17
    30
    QtyArrives
    30 Fri, Jul 17
    Questions? Call 1-888-757-4774
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  • WX-255 (149S147), 81 Gal. WELL-X-TROL Well Tank Product Image
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    WX-255 (149S147), 81 Gal. WELL-X-TROL Well Tank WX-255 WX-255 (149S147), 81 Gal. WELL-X-TROL Well Tank
    SKU: WX-255
    Brand: Amtrol
    (32)
    $724.99 each
    27
    Wed, Jul 22 – Fri, Jul 24
    27
    QtyArrives
    27 Wed, Jul 22 – Fri, Jul 24
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  • WX-202 (144S29), 20 Gal. WELL-X-TROL Well Tank Product Image
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    WX-202 (144S29), 20 Gal. WELL-X-TROL Well Tank WX-202 WX-202 (144S29), 20 Gal. WELL-X-TROL Well Tank
    SKU: WX-202
    Brand: Amtrol
    (57)
    $217.99 each
    35
    Fri, Jul 17
    35
    QtyArrives
    35 Fri, Jul 17
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  • RP-15HP, 20 Gal<br>Residential Pressuriser Product Image
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    RP-15HP, 20 Gal Residential Pressuriser 2201-39 RP-15HP, 20 Gal Residential Pressuriser
    SKU: 2201-39
    Brand: Amtrol
    (9)
    $1,234.99 each
    5
    Wed, Jul 22 – Fri, Jul 24
    5
    QtyArrives
    5 Wed, Jul 22 – Fri, Jul 24
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  • WX-251 (145S10), 62 Gal. WELL-X-TROL Well Tank Product Image
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    WX-251 (145S10), 62 Gal. WELL-X-TROL Well Tank WX-251 WX-251 (145S10), 62 Gal. WELL-X-TROL Well Tank
    SKU: WX-251
    Brand: Amtrol
    (32)
    $759.99 each
    30
    Wed, Jul 22 – Fri, Jul 24
    30
    QtyArrives
    30 Wed, Jul 22 – Fri, Jul 24
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  • RP-10HP, 14 Gal<br>Residential Pressuriser Product Image
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    RP-10HP, 14 Gal Residential Pressuriser 2201-37 RP-10HP, 14 Gal Residential Pressuriser
    SKU: 2201-37
    Brand: Amtrol
    (6)
    $974.99 each
    1
    Fri, Jul 17
    1
    QtyArrives
    1 Fri, Jul 17
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  • THERM-X-TROL ST-25V Expansion Tank<br>(10.3 Gallon) Product Image
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    THERM-X-TROL ST-25V Expansion Tank (10.3 Gallon) 143N164 THERM-X-TROL ST-25V Expansion Tank (10.3 Gallon)
    SKU: 143N164
    Brand: Amtrol
    (7)
    $139.99 each
    114
    Fri, Jul 17
    114
    QtyArrives
    114 Fri, Jul 17
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  • WX-202XL (144S240)<br>26 Gal. WELL-X-TROL<br>Well Tank Product Image
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    WX-202XL (144S240) 26 Gal. WELL-X-TROL Well Tank WX-202XL WX-202XL (144S240) 26 Gal. WELL-X-TROL Well Tank
    SKU: WX-202XL
    Brand: Amtrol
    (47)
    $272.99 each
    11
    Fri, Jul 17
    11
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    11 Fri, Jul 17
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  • WX-205 (147S44)<br>34 Gal. WELL-X-TROL Product Image
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    WX-205 (147S44) 34 Gal. WELL-X-TROL WX-205 WX-205 (147S44) 34 Gal. WELL-X-TROL
    SKU: WX-205
    Brand: Amtrol
    (23)
    $419.99 each
    43
    Fri, Jul 17
    43
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    43 Fri, Jul 17
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  • RP-25HP, 34 Gal<br>Residential Pressuriser Product Image
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    RP-25HP, 34 Gal Residential Pressuriser 2201-28 RP-25HP, 34 Gal Residential Pressuriser
    SKU: 2201-28
    Brand: Amtrol
    (1)
    $1,759.99 each
    2
    Wed, Jul 22 – Fri, Jul 24
    2
    QtyArrives
    2 Wed, Jul 22 – Fri, Jul 24
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  • WX-252 (145S20), 86 Gal. WELL-X-TROL Well Tank Product Image
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    WX-252 (145S20), 86 Gal. WELL-X-TROL Well Tank WX-252 WX-252 (145S20), 86 Gal. WELL-X-TROL Well Tank
    SKU: WX-252
    Brand: Amtrol
    (9)
    $989.99 each
    4
    Wed, Jul 22 – Fri, Jul 24
    4
    QtyArrives
    4 Wed, Jul 22 – Fri, Jul 24
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  • WX-250 (145S1), 44 Gal<br>WELL-X-TROL Well Tank<br>w/ Durabase Stand Product Image
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    WX-250 (145S1), 44 Gal WELL-X-TROL Well Tank w/ Durabase Stand WX-250D WX-250 (145S1), 44 Gal WELL-X-TROL Well Tank w/ Durabase Stand
    SKU: WX-250D
    Brand: Amtrol
    (8)
    $527.99 each
    45
    Fri, Jul 17
    45
    QtyArrives
    45 Fri, Jul 17
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  • WX-255 (149S147), 81 Gal<br>WELL-X-TROL Well Tank<br>w/ Durabase Stand Product Image
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    WX-255 (149S147), 81 Gal WELL-X-TROL Well Tank w/ Durabase Stand WX-255D WX-255 (149S147), 81 Gal WELL-X-TROL Well Tank w/ Durabase Stand
    SKU: WX-255D
    Brand: Amtrol
    (3)
    $785.99 each
    13
    Wed, Jul 22 – Fri, Jul 24
    13
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    13 Wed, Jul 22 – Fri, Jul 24
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  • THERM-X-SPAN T-5 Expansion Tank<br>(2 Gallon) Product Image
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    THERM-X-SPAN T-5 Expansion Tank (2 Gallon) 140735 THERM-X-SPAN T-5 Expansion Tank (2 Gallon)
    SKU: 140735
    Brand: Amtrol
    (17)
    $30.99 each
    93
    Fri, Jul 17
    93
    QtyArrives
    93 Fri, Jul 17
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  • WX1-302 (150S92)<br>86 Gal. WELL-X-TROL<br>Well-X1 Well Tank (Blue) Product Image
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    WX1-302 (150S92) 86 Gal. WELL-X-TROL Well-X1 Well Tank (Blue) WX1-302 WX1-302 (150S92) 86 Gal. WELL-X-TROL Well-X1 Well Tank (Blue)
    SKU: WX1-302
    Brand: Amtrol
    (3)
    $1,049.99 each
    13
    Wed, Jul 22 – Fri, Jul 24
    13
    QtyArrives
    13 Wed, Jul 22 – Fri, Jul 24
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  • WX-101 (140PR1)<br>2 Gal. WELL-X-TROL<br>In-Line Well Tank Product Image
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    WX-101 (140PR1) 2 Gal. WELL-X-TROL In-Line Well Tank WX-101 WX-101 (140PR1) 2 Gal. WELL-X-TROL In-Line Well Tank
    SKU: WX-101
    Brand: Amtrol
    (16)
    $73.29 each
    47
    Fri, Jul 17
    47
    QtyArrives
    47 Fri, Jul 17
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  • THERM-X-TROL ST-8 Expansion Tank Product Image
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    THERM-X-TROL ST-8 Expansion Tank 140N738 THERM-X-TROL ST-8 Expansion Tank
    SKU: 140N738
    Brand: Amtrol
    (15)
    $51.39 each
    49
    Fri, Jul 17
    49
    QtyArrives
    49 Fri, Jul 17
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  • WX-203 (146S30), 32 Gal<br>WELL-X-TROL Well Tank<br>w/ Durabase Stand Product Image
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    WX-203 (146S30), 32 Gal WELL-X-TROL Well Tank w/ Durabase Stand WX-203D WX-203 (146S30), 32 Gal WELL-X-TROL Well Tank w/ Durabase Stand
    SKU: WX-203D
    Brand: Amtrol
    (5)
    $414.99 each
    4
    Fri, Jul 17
    4
    QtyArrives
    4 Fri, Jul 17
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FAQs, Manuals & Videos

Resources

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  • 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 Size Calculator located here.

    We offer a wide selection of
    Therm-X-Trol and Well-X-Trol expansion tanks to suit all of your plumbing and heating needs.

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