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Expansion Tanks

Expansion Tanks

  • 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
    112
    Wed, Jul 22
    112
    QtyArrives
    112 Wed, Jul 22
    Questions? Call 1-888-757-4774
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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
    20
    Wed, Jul 22
    20
    QtyArrives
    20 Wed, Jul 22
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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
    180
    Wed, Jul 22
    180
    QtyArrives
    180 Wed, Jul 22
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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
    40
    Mon, Jul 27 – Wed, Jul 29
    40
    QtyArrives
    40 Mon, Jul 27 – Wed, Jul 29
    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
    197
    Wed, Jul 22
    197
    QtyArrives
    197 Wed, Jul 22
    Questions? Call 1-888-757-4774
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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
    (29)
    $734.99 each
    30
    Mon, Jul 27 – Wed, Jul 29
    30
    QtyArrives
    30 Mon, Jul 27 – Wed, Jul 29
    Questions? Call 1-888-757-4774
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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
    23
    Wed, Jul 22
    23
    QtyArrives
    23 Wed, Jul 22
    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
    61
    Mon, Jul 27 – Wed, Jul 29
    61
    QtyArrives
    61 Mon, Jul 27 – Wed, Jul 29
    Questions? Call 1-888-757-4774
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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
    36
    Wed, Jul 22
    36
    QtyArrives
    36 Wed, Jul 22
    Questions? Call 1-888-757-4774
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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
    Mon, Jul 27 – Wed, Jul 29
    5
    QtyArrives
    5 Mon, Jul 27 – Wed, Jul 29
    Questions? Call 1-888-757-4774
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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
    27
    Mon, Jul 27 – Wed, Jul 29
    27
    QtyArrives
    27 Mon, Jul 27 – Wed, Jul 29
    Questions? Call 1-888-757-4774
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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
    Wed, Aug 12 – Wed, Aug 19
    Arrives
    Wed, Aug 12 – Wed, Aug 19
    Questions? Call 1-888-757-4774 or LiveChat Img Chat Us
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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
    109
    Wed, Jul 22
    109
    QtyArrives
    109 Wed, Jul 22
    Questions? Call 1-888-757-4774
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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
    6
    Wed, Jul 22
    6
    QtyArrives
    6 Wed, Jul 22
    Questions? Call 1-888-757-4774
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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
    40
    Wed, Jul 22
    40
    QtyArrives
    40 Wed, Jul 22
    Questions? Call 1-888-757-4774
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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
    Mon, Jul 27 – Wed, Jul 29
    2
    QtyArrives
    2 Mon, Jul 27 – Wed, Jul 29
    Questions? Call 1-888-757-4774
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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
    Mon, Jul 27 – Wed, Jul 29
    4
    QtyArrives
    4 Mon, Jul 27 – Wed, Jul 29
    Questions? Call 1-888-757-4774
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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
    43
    Wed, Jul 22
    43
    QtyArrives
    43 Wed, Jul 22
    Questions? Call 1-888-757-4774
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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
    12
    Mon, Jul 27 – Wed, Jul 29
    12
    QtyArrives
    12 Mon, Jul 27 – Wed, Jul 29
    Questions? Call 1-888-757-4774
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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
    74
    Wed, Jul 22
    74
    QtyArrives
    74 Wed, Jul 22
    Questions? Call 1-888-757-4774
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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
    12
    Mon, Jul 27 – Wed, Jul 29
    12
    QtyArrives
    12 Mon, Jul 27 – Wed, Jul 29
    Questions? Call 1-888-757-4774
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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
    41
    Wed, Jul 22
    41
    QtyArrives
    41 Wed, Jul 22
    Questions? Call 1-888-757-4774
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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
    46
    Wed, Jul 22
    46
    QtyArrives
    46 Wed, Jul 22
    Questions? Call 1-888-757-4774
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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
    (6)
    $414.99 each
    3
    Wed, Jul 22
    3
    QtyArrives
    3 Wed, Jul 22
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FAQs, Manuals & Videos
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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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