Expansion Tanks

  • THERM-X-TROL ST-5 Expansion Tank
    SKU: 140N43
    Brand: Amtrol
    (44)
    $45.95 each
    $176.60 box of 4
    $44.15 each
    221
    Wed, Feb 27
    237
    QtyArrives
    221 Wed, Feb 27
    16 Thu, Feb 28
    Questions? Call 1-888-757-4774
  • THERM-X-TROL ST-12 Expansion Tank
    SKU: 141N43
    Brand: Amtrol
    (33)
    $61.45 each
    $235.80 box of 4
    $58.95 each
    178
    Wed, Feb 27
    182
    QtyArrives
    178 Wed, Feb 27
    4 Thu, Feb 28
    Questions? Call 1-888-757-4774
  • 11" HydroClaw Expansion Tank Support Bracket
    SKU: HC11-A
    Brand: Storm King Enterprises
    (37)
    $40.95 each
    60
    Wed, Feb 27
    60
    QtyArrives
    60 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • 3/4" Threaded Spring Loaded Check Valve, Lead Free
    SKU: SLCT075
    Brand: Bluefin
    (27)
    $9.15 each
    $91.80 box of 12
    $7.65 each
    924
    Wed, Feb 27
    924
    QtyArrives
    924 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • 1" Threaded Spring Loaded Check Valve Lead Free
    SKU: SLCT100
    Brand: Bluefin
    (27)
    $11.85 each
    $98.50 box of 10
    $9.85 each
    564
    Wed, Feb 27
    564
    QtyArrives
    564 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • PLT-5, 2.1 Gallon Potable Water Expansion Tank
    SKU: 0067370
    Brand: Watts
    (4)
    $39.55 each
    107
    Wed, Feb 27
    107
    QtyArrives
    107 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • $14.85 each
    $142.50 box of 10
    $14.25 each
    137
    Wed, Feb 27
    137
    QtyArrives
    137 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • $17.25 each
    $165.50 box of 10
    $16.55 each
    135
    Wed, Feb 27
    135
    QtyArrives
    135 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • WX-250 (145S1), 44 Gal. WELL-X-TROL Well Tank
    SKU: WX-250
    Brand: Amtrol
    (66)
    $515.95 each
    $990.70 box of 2
    $495.35 each
    141
    Wed, Feb 27
    141
    QtyArrives
    141 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • 1/2" Threaded Spring Loaded Check Valve, Lead Free
    SKU: SLCT050
    Brand: Bluefin
    (27)
    $6.15 each
    $77.25 box of 15
    $5.15 each
    974
    Wed, Feb 27
    974
    QtyArrives
    974 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • 8" HydroClaw Expansion Tank Support Bracket
    SKU: HC8-B
    Brand: Storm King Enterprises
    (23)
    $30.95 each
    28
    Wed, Feb 27
    28
    QtyArrives
    28 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • WX-203 (146S30), 32 Gal. WELL-X-TROL Well Tank
    SKU: WX-203
    Brand: Amtrol
    (60)
    $424.95 each
    $815.90 box of 2
    $407.95 each
    112
    Wed, Feb 27
    112
    QtyArrives
    112 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • WX-202 (144S29), 20 Gal. WELL-X-TROL Well Tank
    SKU: WX-202
    Brand: Amtrol
    (46)
    $229.95 each
    $441.50 box of 2
    $220.75 each
    110
    Wed, Feb 27
    110
    QtyArrives
    110 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • Pressure Switch, 40/60 PSI, 10 Amp, DPST
    SKU: 9013FSG2J24
    Brand: Square D
    (10)
    $14.75 each
    55
    Wed, Feb 27
    148
    QtyArrives
    55 Wed, Feb 27
    93 Thu, Feb 28
    Questions? Call 1-888-757-4774
  • THERM-X-SPAN T-5 Expansion Tank (2 Gallon)
    SKU: 140735
    Brand: Amtrol
    (12)
    $37.25 each
    $143.00 box of 4
    $35.75 each
    140
    Wed, Feb 27
    140
    QtyArrives
    140 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • THERM-X-TROL ST-8 Expansion Tank
    SKU: 140N738
    Brand: Amtrol
    (11)
    $55.55 each
    $213.40 box of 4
    $53.35 each
    48
    Wed, Feb 27
    48
    QtyArrives
    48 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • WX-202XL (144S240) 26 Gal. WELL-X-TROL Well Tank
    SKU: WX-202XL
    Brand: Amtrol
    (38)
    $279.95 each
    $537.50 box of 2
    $268.75 each
    30
    Wed, Feb 27
    30
    QtyArrives
    30 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • Water Pump Pressure Switch, 30/50 PSI, DPST
    SKU: 9013FSG2J21
    Brand: Square D
    (1)
    $12.25 each
    26
    Wed, Feb 27
    93
    QtyArrives
    26 Wed, Feb 27
    67 Thu, Feb 28
    Questions? Call 1-888-757-4774
  • WX-302 (150S1), 86 Gal. WELL-X-TROL Well Tank
    SKU: WX-302
    Brand: Amtrol
    (25)
    $709.95 each
    $1,363.10 box of 2
    $681.55 each
    45
    Mon, Mar 4 – Wed, Mar 6
    45
    QtyArrives
    45 Mon, Mar 4 – Wed, Mar 6
    Questions? Call 1-888-757-4774
  • $72.95 each
    $280.20 box of 4
    $70.05 each
    47
    Wed, Feb 27
    47
    QtyArrives
    47 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • THERM-X-TROL ST-25V Expansion Tank (10.3 Gallon)
    SKU: 143N164
    Brand: Amtrol
    (6)
    $149.95 each
    $431.85 box of 3
    $143.95 each
    88
    Wed, Feb 27
    88
    QtyArrives
    88 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • 1-1/4" Threaded Spring Loaded Check Valve, Lead Free
    SKU: SLCT125
    Brand: Bluefin
    (27)
    $21.25 each
    $142.00 box of 8
    $17.75 each
    224
    Wed, Feb 27
    224
    QtyArrives
    224 Wed, Feb 27
    Questions? Call 1-888-757-4774
  • WX-255 (149S147), 81 Gal. WELL-X-TROL Well Tank
    SKU: WX-255
    Brand: Amtrol
    (27)
    $759.95 each
    $1,459.10 box of 2
    $729.55 each
    45
    Mon, Mar 4 – Wed, Mar 6
    45
    QtyArrives
    45 Mon, Mar 4 – Wed, Mar 6
    Questions? Call 1-888-757-4774
  • WX-350 (151S1) 119 Gal. WELL-X-TROL Well Tank
    SKU: WX-350
    Brand: Amtrol
    (17)
    $1,019.95 each
    $1,958.30 box of 2
    $979.15 each
    23
    Mon, Mar 4 – Wed, Mar 6
    23
    QtyArrives
    23 Mon, Mar 4 – Wed, Mar 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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