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How To: Size Expansion Tanks Using Wessels Free Tank Calculator

Wessels Company is proud to offer a free web and phone app (iOS and android) for sizing and converting a selection of our tank products online or on your phone.

In our easy-to-use app guide, you will find a quick reference page explaining the icons. Here are the icons most commonly found on the app:


The calculator allows you to select the type of tank you wish to size: HVAC expansion, domestic hot water, well & pressure booster, and buffer. You can also use the app to convert a compression style expansion tank to a removable bladder or fixed-diaphragm design. To learn more about each category of product, simply click or tap the (?) help buttons next to each product.

On each tank page, you will see a series of entry fields and drop down menus that will need to be filled out to determine the tank size you need for the job.


For HVAC expansion tanks, the first field you will need to answer is System Volume in gallons. If you don’t know your system’s volume, you can click the System Volume Estimator to get an idea.

You will also need to know the fluid type used within the system and the operating temperature range.  Finally, you will need the initial and final pressure, which both have estimators that can help determine an approximate value.

When you are ready to size your tank, click “Calculate” and you will be taken to the calculated critical sizing page.  Here you will be given a “Required Tank Volume” and product suggestions based on that calculation.


Once you’ve selected a product, the final page of the app will display the product submittal, installation & operation manual, and brochure.  If you decide to request a quote to purchase the product, you can click “Request Quote” and the app will auto-generate an email with your calculations that you can then send to the Wessels quotation department.

Wessels makes it easy to determine which product is best suited for your job, which volume is needed, and the details of the product.  Remember, if you are unsure about your selection, Wessels Company’s friendly customer service is available to help ensure you make the right selection. Send us an email at [email protected], give us a call at 317-888-9800 or live chat with us right on our website by clicking the floating “Start Chat” window.

You can find the Wessels tank sizing app online at or you can download it to your iOS or Android phone by searching your app store for “Wessels Company”.