How you replace your Expansion Tank

Do you have issues with your expansion tank and have decided to replace it? We have compiled a step-by-step guide to help you feel confident in carrying out the replacement.

NOTE: We do not recommend replacing the expansion tank if it is located inside the pump; this guide is for external tanks only.

While not all installations are identical, many share similarities. There are various manufacturers of expansion tanks, with some of the largest being IVT, Canvac, Daikin, Mitsubishi Electric, and many more.

Estimated time for replacement: 1-2 hours

Tools and materials you will need: Thread tape, such as Loctite tape

Step 1: Once you have located the expansion tank, it's a good idea to inspect it before disassembling. If you haven't already purchased a new replacement part, check the tank's size, make note of the brand, and its settings. Another tip is to take a photo of the old tank for reference during the installation.

It's crucial to ensure that the size of your new expansion tank is correct. As a general rule, it's better to have a slightly larger expansion tank than one that's too small, as water expands by approximately 5-8% when heated.

Step 2: Once you've confirmed that you have the correct size for your new expansion tank, proceed by turning off the circulation pump. Then, shut off the valves on the heating system at the exchangers (if applicable).

Step 3: With these steps completed, release the excess pressure through the safety valve located on the expansion tank. If water comes out instead of air, there may be a hole in the bladder. To facilitate the replacement, drain the water from the tank before disassembly.

Step 4: Once the expansion tank is empty of water, you can begin the disassembly by turning the tank counterclockwise. Despite being emptied, some dripping water may still occur, so it's a good idea to have a towel handy.

Step 5: Now, place the new expansion tank in position and ensure it seals tightly. Use Loctite tape along the threads for a secure seal.

Step 6: Repressurize and bleed the system at the radiators. The recommended pressure varies depending on the manufacturer, so consult the user manual if needed.

Step 7: Once the new expansion tank is in place and set to the appropriate pressure, reopen the valves on the heating system at the exchangers (if any), and then start the circulation pump.

Your new expansion tank is now installed—well done!