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Expansion Tanks
Lead Content Warning
Do not use this item for any installation or repair of potable water applications. This product does not comply with the "Safe Drinking Water Act," which requires that products meet low-lead standards in order to be used in systems providing water for human consumption (drinking or cooking). This item is for non-potable (non-human consumption) water applications only.
Lead Content Warning
This product does not comply with the Safe Drinking Water Act, which requires that products used in any system providing water for human consumption (drinking or cooking) to meet low-lead standards. Please check the box below to confirm you are aware that this item is for non-potable water applications only.
You must agree to this statement in order to purchase this product.
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THERM-X-TROL ST-5 Expansion TankSKU: 140N43Brand: Amtrol
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THERM-X-TROL ST-12 Expansion TankSKU: 141N43Brand: Amtrol(34) -
PLT-5, 2.1 Gallon Potable Water Expansion TankSKU: 0067370Brand: Watts(7) -
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WX-350 (151S1) 119 Gal. WELL-X-TROL Well TankSKU: WX-350Brand: Amtrol(17) -
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WX-250 (145S1), 44 Gal. WELL-X-TROL Well TankSKU: WX-250Brand: Amtrol(68) -
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WX-302 (150S1), 86 Gal. WELL-X-TROL Well TankSKU: WX-302Brand: Amtrol(26) -
![WX-203 (146S30), 32 Gal. WELL-X-TROL Well Tank Product Image]()
WX-203 (146S30), 32 Gal. WELL-X-TROL Well TankSKU: WX-203Brand: Amtrol(60) -
![WX-255 (149S147), 81 Gal. WELL-X-TROL Well Tank Product Image]()
WX-255 (149S147), 81 Gal. WELL-X-TROL Well TankSKU: WX-255Brand: Amtrol(27) -
![WX-202 (144S29), 20 Gal. WELL-X-TROL Well Tank Product Image]()
WX-202 (144S29), 20 Gal. WELL-X-TROL Well TankSKU: WX-202Brand: Amtrol(49) -
![RP-15HP, 20 Gal<br>Residential Pressuriser Product Image]()
RP-15HP, 20 Gal Residential PressuriserSKU: 2201-39Brand: Amtrol(9) -
![WX-251 (145S10), 62 Gal. WELL-X-TROL Well Tank Product Image]()
WX-251 (145S10), 62 Gal. WELL-X-TROL Well TankSKU: WX-251Brand: Amtrol(32) -
![RP-10HP, 14 Gal<br>Residential Pressuriser Product Image]()
RP-10HP, 14 Gal Residential PressuriserSKU: 2201-37Brand: Amtrol(3) -
![THERM-X-TROL ST-25V Expansion Tank<br>(10.3 Gallon) Product Image]()
THERM-X-TROL ST-25V Expansion Tank (10.3 Gallon)SKU: 143N164Brand: Amtrol(7) -
![WX-202XL (144S240)<br>26 Gal. WELL-X-TROL<br>Well Tank Product Image]()
WX-202XL (144S240) 26 Gal. WELL-X-TROL Well TankSKU: WX-202XLBrand: Amtrol(40) -
![WX-205 (147S44)<br>34 Gal. WELL-X-TROL Product Image]()
WX-205 (147S44) 34 Gal. WELL-X-TROLSKU: WX-205Brand: Amtrol(19) -
![RP-25HP, 34 Gal<br>Residential Pressuriser Product Image]()
RP-25HP, 34 Gal Residential PressuriserSKU: 2201-28Brand: Amtrol(1) -
![WX-252 (145S20), 86 Gal. WELL-X-TROL Well Tank Product Image]()
WX-252 (145S20), 86 Gal. WELL-X-TROL Well TankSKU: WX-252Brand: Amtrol(6) -
![WX-250 (145S1), 44 Gal<br>WELL-X-TROL Well Tank<br>w/ Durabase Stand Product Image]()
WX-250 (145S1), 44 Gal WELL-X-TROL Well Tank w/ Durabase StandSKU: WX-250DBrand: Amtrol(5)Mon, Sep 23 – Mon, Sep 30 -
![WX-255 (149S147), 81 Gal<br>WELL-X-TROL Well Tank<br>w/ Durabase Stand Product Image]()
WX-255 (149S147), 81 Gal WELL-X-TROL Well Tank w/ Durabase StandSKU: WX-255DBrand: Amtrol(2) -
![THERM-X-SPAN T-5 Expansion Tank<br>(2 Gallon) Product Image]()
THERM-X-SPAN T-5 Expansion Tank (2 Gallon)SKU: 140735Brand: Amtrol(12) -
![WX1-302 (150S92)<br>86 Gal. WELL-X-TROL<br>Well-X1 Well Tank (Blue) Product Image]()
WX1-302 (150S92) 86 Gal. WELL-X-TROL Well-X1 Well Tank (Blue)SKU: WX1-302Brand: Amtrol(2) -
![WX-101 (140PR1)<br>2 Gal. WELL-X-TROL<br>In-Line Well Tank Product Image]()
WX-101 (140PR1) 2 Gal. WELL-X-TROL In-Line Well TankSKU: WX-101Brand: Amtrol(15)Mon, Sep 23 – Mon, Sep 30 -
![THERM-X-TROL ST-8 Expansion Tank Product Image]()
THERM-X-TROL ST-8 Expansion TankSKU: 140N738Brand: Amtrol(13) -
![WX-203 (146S30), 32 Gal<br>WELL-X-TROL Well Tank<br>w/ Durabase Stand Product Image]()
WX-203 (146S30), 32 Gal WELL-X-TROL Well Tank w/ Durabase StandSKU: WX-203DBrand: Amtrol(3) -
![WX-350 (151S1), 119 Gal<br>WELL-X-TROL Well Tank<br>w/ Durabase Stand Product Image]()
WX-350 (151S1), 119 Gal WELL-X-TROL Well Tank w/ Durabase StandSKU: WX-350DBrand: Amtrol(1) -
![THERM-X-TROL ST-60V Expansion Tank<br>(34 Gallon) Product Image]()
THERM-X-TROL ST-60V Expansion Tank (34 Gallon)SKU: 147N130Brand: Amtrol -
![WX-103 (142PR1)<br>7.6 Gal. WELL-X-TROL<br>In-Line Well Tank Product Image]()
WX-103 (142PR1) 7.6 Gal. WELL-X-TROL In-Line Well TankSKU: WX-103Brand: Amtrol(5) -
![THERM-X-TROL ST-30V Expansion Tank<br>(14 Gallon) Product Image]()
THERM-X-TROL ST-30V Expansion Tank (14 Gallon)SKU: 143N273Brand: Amtrol(7) -
![WX-102 (141PR1)<br>4.4 Gal. WELL-X-TROL<br>In-Line Well Tank Product Image]()
WX-102 (141PR1) 4.4 Gal. WELL-X-TROL In-Line Well TankSKU: WX-102Brand: Amtrol(13) -
![WX-201 (143S29), 14 Gal. WELL-X-TROL Well Tank Product Image]()
WX-201 (143S29), 14 Gal. WELL-X-TROL Well TankSKU: WX-201Brand: Amtrol(3)
Resources
Articles
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More About Expansion Tanks
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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