Shop Milwaukee

Filters

108 items
Reset

SORT

Top Sellers
Default
Price ▲
Price ▼

Product Availability

Show In Stock Only (76)

Brand

Amtrol (35)
Axiom (4)
Bell & Gossett (15)
Bluefin (5)
Flamco (7)
Holdrite (1)
Raven (3)
Resideo (12)
Sioux Chief (4)
Storm King Enterprises (2)
See More

Tank Volume

2 Gallons (9)
2.1 Gallons (1)
4.4 Gallons (9)
4.5 Gallons (1)
4.75 Gallons (1)
6 Gallons (1)
6.6 Gallons (1)
6.7 Gallons (1)
7.4 Gallons (1)
7.6 Gallons (4)
See More

Review Score

(42)
(3)
(1)
(1)

Price Range

$5 to $10 (1)
$10 to $15 (2)
$15 to $20 (2)
$20 to $25 (1)
$25 to $30 (6)
$30 to $35 (1)
$35 to $40 (3)
$40 to $45 (4)
$45 to $50 (2)
$50 to $60 (6)
See More

Boiler Expansion Tanks

Help Face
Need a little help?
View our Resources
108 items
Grid
List

Resources

Videos

See all
Play Icon
How Expansion Tanks Work

Articles

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 Sizing Calculator.

We offer a wide selection of Amtrol, Watts, and Bell & Gossett expansion tanks to suit all of your plumbing and heating needs.
Questions?
MondayThursday
8am7:45pm
Friday
9am7:45pm
SaturdaySunday
9am5:45pm

Available 8am
Available 8am
Response by Thurs

or check out our Support Center
Compare
Product Image of #30 Extrol EX-30 Expansion Tank (4.4 Gallon Volume)
$62.99 each
In Stock
Fast Track Logo
Get 561 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 561 by Fri, Feb 14
More Available
Compare
Product Image of QuickStrap Expansion Tank Mounting Bracket (5 Gal. Capacity)
$16.90 each
In Stock
Fast Track Logo
Get 581 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 581 by Fri, Feb 14
More Available
Compare
Product Image of ETX-30, 4.5 Gallon Non-Potable Water Expansion Tank
$53.02 each
In Stock
Fast Track Logo
Get 762 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 762 by Fri, Feb 14
More Available
Compare
Product Image of #15 Extrol EX-15 Expansion Tank (2 Gallon Volume)
#15 Extrol EX-15 Expansion Tank (2 Gallon Volume)
SKU: 101-1
Amtrol
SKU: 101-1
Brand: Amtrol
(100)
$48.99 each
In Stock
Fast Track Logo
Get 75 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 75 by Fri, Feb 14
More Available
Compare
Product Image of 1/2" Pro-Pal Full Port Brass Ball Valve w/ Hi-Flow Hose Drain (600 WOG)
$28.99 each
In Stock
Fast Track Logo
Get 689 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 689 by Fri, Feb 14
More Available
Compare
Product Image of #60 Extrol EX-60 Expansion Tank (6.7 Gallon Volume)
$124.26 each
In Stock
Fast Track Logo
Get 77 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 77 by Fri, Feb 14
More Available
Compare
Product Image of 14 Gallon Vertical Expansion Tank
14 Gallon Vertical Expansion Tank
SKU: EXH14V
Bluefin
SKU: EXH14V
Brand: Bluefin
$177.47 each
In Stock
Fast Track Logo
Get 215 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 215 by Fri, Feb 14
More Available
Compare
Product Image of 11" HydroClaw Expansion Tank Support Bracket
$45.38 each
In Stock
Fast Track Logo
Get 193 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 193 by Fri, Feb 14
More Available
Compare
Product Image of Model 110 Fill-Trol w/ Valve (4.4 Gallon Volume)
$117.61 each
In Stock
Fast Track Logo
Get 13 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 13 by Fri, Feb 14
More Available
Compare
Product Image of 8" HydroClaw Expansion Tank Support Bracket
$35.70 each
In Stock
Fast Track Logo
Get 121 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 121 by Fri, Feb 14
More Available
Compare
Product Image of Expansion Tank Wall Bracket (Pro Kit w/ ETV-1)
Expansion Tank Wall Bracket (Pro Kit w/ ETV-1)
SKU: HN-3
Axiom
SKU: HN-3
Brand: Axiom
(4)
$115.29 each
In Stock
Fast Track Logo
Get 104 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 104 by Fri, Feb 14
More Available
Compare
Product Image of 1/2" Expansion Tank Isolator w/ Waste (Male x Female)
$7.81 each
BOX UP & SAVE 10%
$70.40 box of 10
$7.04 each
In Stock
Fast Track Logo
Get 127 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 127 by Fri, Feb 14
More Available
Compare
Product Image of SX-30V Extrol Expansion Tank (14 Gallon Volume)
$261.35 each
In Stock
Fast Track Logo
Get 35 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 35 by Fri, Feb 14
More Available
Compare
Product Image of ETX-60, 6.0 Gallon Non-Potable Water Expansion Tank
$90.68 each
In Stock
Fast Track Logo
Get 148 by Fri, Feb 14
More Available
In Stock
Fast Track Logo
Get 148 by Fri, Feb 14
More Available
Compare
Product Image of Flamco Flexconsole - 1/2" x 1/2" NPT - Steel (Red)
$30.76 each