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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
    212
    Tue, Sep 3
    212
    QtyArrives
    212 Tue, Sep 3
    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
    24
    Tue, Sep 3
    24
    QtyArrives
    24 Tue, Sep 3
    Questions? Call 1-888-757-4774
  • PLT-5, 2.1 Gallon Potable<br>Water Expansion Tank Product Image
    $42.99 each
    378
    Tue, Sep 3
    378
    QtyArrives
    378 Tue, Sep 3
    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
    33
    Thu, Sep 5 – Mon, Sep 9
    33
    QtyArrives
    33 Thu, Sep 5 – Mon, Sep 9
    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
    15
    Tue, Sep 3
    15
    QtyArrives
    15 Tue, Sep 3
    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
    45
    Thu, Sep 5 – Mon, Sep 9
    45
    QtyArrives
    45 Thu, Sep 5 – Mon, Sep 9
    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
    74
    Tue, Sep 3
    74
    QtyArrives
    74 Tue, Sep 3
    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
    25
    Thu, Sep 5 – Mon, Sep 9
    25
    QtyArrives
    25 Thu, Sep 5 – Mon, Sep 9
    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
    11
    Tue, Sep 3
    11
    QtyArrives
    11 Tue, Sep 3
    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
    Thu, Sep 5 – Mon, Sep 9
    11
    QtyArrives
    11 Thu, Sep 5 – Mon, Sep 9
    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
    21
    Thu, Sep 5 – Mon, Sep 9
    21
    QtyArrives
    21 Thu, Sep 5 – Mon, Sep 9
    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
    11
    Tue, Sep 3
    11
    QtyArrives
    11 Tue, Sep 3
    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
    73
    Tue, Sep 3
    73
    QtyArrives
    73 Tue, Sep 3
    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
    26
    Tue, Sep 3
    26
    QtyArrives
    26 Tue, Sep 3
    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
    18
    Tue, Sep 3
    18
    QtyArrives
    18 Tue, Sep 3
    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
    Thu, Sep 5 – Mon, Sep 9
    2
    QtyArrives
    2 Thu, Sep 5 – Mon, Sep 9
    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
    Thu, Sep 5 – Mon, Sep 9
    6
    QtyArrives
    6 Thu, Sep 5 – Mon, Sep 9
    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
    Mon, Sep 23 – Mon, Sep 30
    Arrives
    Mon, Sep 23 – Mon, Sep 30
    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
    Thu, Sep 5 – Mon, Sep 9
    10
    QtyArrives
    10 Thu, Sep 5 – Mon, Sep 9
    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
    96
    Tue, Sep 3
    96
    QtyArrives
    96 Tue, Sep 3
    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
    Thu, Sep 26 – Mon, Oct 7
    Arrives
    Thu, Sep 26 – Mon, Oct 7
    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
    Mon, Sep 23 – Mon, Sep 30
    Arrives
    Mon, Sep 23 – Mon, Sep 30
    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
    3
    Tue, Sep 3
    3
    QtyArrives
    3 Tue, Sep 3
    Questions? Call 1-888-757-4774
  • WX-203 (146S30), 32 Gal<br>WELL-X-TROL Well Tank<br>w/ Durabase Stand Product Image
    $399.99 each
    17
    Tue, Sep 3
    17
    QtyArrives
    17 Tue, Sep 3
    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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