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Expansion Tanks

  • THERM-X-TROL ST-5 Expansion Tank Product Image
    THERM-X-TROL ST-5 Expansion Tank
    SKU: 140N43
    Brand: Amtrol
    (47)
    $45.95 each
    $176.60 box of 4
    $44.15 each
    198
    Fri, Sep 6
    198
    QtyArrives
    198 Fri, Sep 6
    Questions? Call 1-888-757-4774
  • THERM-X-TROL ST-12 Expansion Tank Product Image
    THERM-X-TROL ST-12 Expansion Tank
    SKU: 141N43
    Brand: Amtrol
    (34)
    $61.45 each
    $235.80 box of 4
    $58.95 each
    19
    Fri, Sep 6
    19
    QtyArrives
    19 Fri, Sep 6
    Questions? Call 1-888-757-4774
  • PLT-5, 2.1 Gallon Potable<br>Water Expansion Tank Product Image
    $42.99 each
    367
    Fri, Sep 6
    367
    QtyArrives
    367 Fri, Sep 6
    Questions? Call 1-888-757-4774
  • WX-350 (151S1)<br>119 Gal. WELL-X-TROL Well Tank Product Image
    $1,015.99 each
    $1,958.30 box of 2
    $979.15 each
    55
    Wed, Sep 11 – Fri, Sep 13
    55
    QtyArrives
    55 Wed, Sep 11 – Fri, Sep 13
    Questions? Call 1-888-757-4774
  • WX-250 (145S1), 44 Gal. WELL-X-TROL Well Tank Product Image
    $479.99 each
    $919.98 box of 2
    $459.99 each
    10
    Fri, Sep 6
    10
    QtyArrives
    10 Fri, Sep 6
    Questions? Call 1-888-757-4774
  • WX-302 (150S1), 86 Gal. WELL-X-TROL Well Tank Product Image
    $708.99 each
    $1,363.10 box of 2
    $681.55 each
    99
    Wed, Sep 11 – Fri, Sep 13
    99
    QtyArrives
    99 Wed, Sep 11 – Fri, Sep 13
    Questions? Call 1-888-757-4774
  • WX-203 (146S30), 32 Gal. WELL-X-TROL Well Tank Product Image
    $375.99 each
    $711.98 box of 2
    $355.99 each
    70
    Fri, Sep 6
    70
    QtyArrives
    70 Fri, Sep 6
    Questions? Call 1-888-757-4774
  • WX-255 (149S147), 81 Gal. WELL-X-TROL Well Tank Product Image
    $699.99 each
    $1,343.98 box of 2
    $671.99 each
    22
    Wed, Sep 11 – Fri, Sep 13
    22
    QtyArrives
    22 Wed, Sep 11 – Fri, Sep 13
    Questions? Call 1-888-757-4774
  • WX-202 (144S29), 20 Gal. WELL-X-TROL Well Tank Product Image
    $209.99 each
    $399.98 box of 2
    $199.99 each
    5
    Fri, Sep 6
    5
    QtyArrives
    5 Fri, Sep 6
    Questions? Call 1-888-757-4774
  • RP-15HP, 20 Gal<br>Residential Pressuriser Product Image
    RP-15HP, 20 Gal Residential Pressuriser
    SKU: 2201-39
    Brand: Amtrol
    (9)
    $1,299.95 each
    $2,495.90 box of 2
    $1,247.95 each
    11
    Wed, Sep 11 – Fri, Sep 13
    11
    QtyArrives
    11 Wed, Sep 11 – Fri, Sep 13
    Questions? Call 1-888-757-4774
  • WX-251 (145S10), 62 Gal. WELL-X-TROL Well Tank Product Image
    $699.99 each
    $1,345.98 box of 2
    $672.99 each
    22
    Wed, Sep 11 – Fri, Sep 13
    22
    QtyArrives
    22 Wed, Sep 11 – Fri, Sep 13
    Questions? Call 1-888-757-4774
  • RP-10HP, 14 Gal<br>Residential Pressuriser Product Image
    RP-10HP, 14 Gal Residential Pressuriser
    SKU: 2201-37
    Brand: Amtrol
    (3)
    $1,025.95 each
    $1,969.90 box of 2
    $984.95 each
    10
    Fri, Sep 6
    10
    QtyArrives
    10 Fri, Sep 6
    Questions? Call 1-888-757-4774
  • THERM-X-TROL ST-25V Expansion Tank<br>(10.3 Gallon) Product Image
    $139.99 each
    $404.97 box of 3
    $134.99 each
    67
    Fri, Sep 6
    67
    QtyArrives
    67 Fri, Sep 6
    Questions? Call 1-888-757-4774
  • WX-202XL (144S240)<br>26 Gal. WELL-X-TROL<br>Well Tank Product Image
    $262.99 each
    $505.98 box of 2
    $252.99 each
    19
    Fri, Sep 6
    19
    QtyArrives
    19 Fri, Sep 6
    Questions? Call 1-888-757-4774
  • WX-205 (147S44)<br>34 Gal. WELL-X-TROL Product Image
    WX-205 (147S44) 34 Gal. WELL-X-TROL
    SKU: WX-205
    Brand: Amtrol
    (19)
    $405.99 each
    $779.98 box of 2
    $389.99 each
    16
    Fri, Sep 6
    16
    QtyArrives
    16 Fri, Sep 6
    Questions? Call 1-888-757-4774
  • RP-25HP, 34 Gal<br>Residential Pressuriser Product Image
    RP-25HP, 34 Gal Residential Pressuriser
    SKU: 2201-28
    Brand: Amtrol
    (1)
    $1,779.95 each
    2
    Wed, Sep 11 – Fri, Sep 13
    2
    QtyArrives
    2 Wed, Sep 11 – Fri, Sep 13
    Questions? Call 1-888-757-4774
  • WX-252 (145S20), 86 Gal. WELL-X-TROL Well Tank Product Image
    $949.99 each
    $1,823.98 box of 2
    $911.99 each
    6
    Wed, Sep 11 – Fri, Sep 13
    6
    QtyArrives
    6 Wed, Sep 11 – Fri, Sep 13
    Questions? Call 1-888-757-4774
  • WX-250 (145S1), 44 Gal<br>WELL-X-TROL Well Tank<br>w/ Durabase Stand Product Image
    $509.99 each
    Fri, Sep 27 – Fri, Oct 4
    Arrives
    Fri, Sep 27 – Fri, Oct 4
    Questions? Call 1-888-757-4774 or LiveChat Img Chat Us
  • WX-255 (149S147), 81 Gal<br>WELL-X-TROL Well Tank<br>w/ Durabase Stand Product Image
    $759.99 each
    10
    Wed, Sep 11 – Fri, Sep 13
    10
    QtyArrives
    10 Wed, Sep 11 – Fri, Sep 13
    Questions? Call 1-888-757-4774
  • THERM-X-SPAN T-5 Expansion Tank<br>(2 Gallon) Product Image
    THERM-X-SPAN T-5 Expansion Tank (2 Gallon)
    SKU: 140735
    Brand: Amtrol
    (12)
    $31.99 each
    $122.76 box of 4
    $30.69 each
    85
    Fri, Sep 6
    85
    QtyArrives
    85 Fri, Sep 6
    Questions? Call 1-888-757-4774
  • WX1-302 (150S92)<br>86 Gal. WELL-X-TROL<br>Well-X1 Well Tank (Blue) Product Image
    $1,024.99 each
    Wed, Oct 2 – Fri, Oct 11
    Arrives
    Wed, Oct 2 – Fri, Oct 11
    Questions? Call 1-888-757-4774 or LiveChat Img Chat Us
  • WX-101 (140PR1)<br>2 Gal. WELL-X-TROL<br>In-Line Well Tank Product Image
    $69.99 each
    $267.96 box of 4
    $66.99 each
    Fri, Sep 27 – Fri, Oct 4
    Arrives
    Fri, Sep 27 – Fri, Oct 4
    Questions? Call 1-888-757-4774 or LiveChat Img Chat Us
  • THERM-X-TROL ST-8 Expansion Tank Product Image
    THERM-X-TROL ST-8 Expansion Tank
    SKU: 140N738
    Brand: Amtrol
    (13)
    $49.99 each
    $191.96 box of 4
    $47.99 each
    Fri, Sep 27 – Fri, Oct 4
    Arrives
    Fri, Sep 27 – Fri, Oct 4
    Questions? Call 1-888-757-4774 or LiveChat Img Chat Us
  • WX-203 (146S30), 32 Gal<br>WELL-X-TROL Well Tank<br>w/ Durabase Stand Product Image
    $399.99 each
    17
    Fri, Sep 6
    17
    QtyArrives
    17 Fri, Sep 6
    Questions? Call 1-888-757-4774

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 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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