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How to Install Hot Water Heater Expansion Tank

A water heater expansion tank is crucial if you install a water heater at home. It helps to control excessive pressure of thermal expansion caused by water heating, which can damage pipes and other plumbing fixtures. Your home needs one if you have a back-flow preventer or check valve throughout the plumbing system.

Installing this expansion tank at your home is easy. Here’s a step to follow.

Materials Needed:

  • Thermal expansion tank
  • Dielectric water heater union
  • Pipe wrench or channel-lock pliers
  • (2) 3/4-inch copper female-threaded unions
  • Pipe-sealing tape
  • 3/4-inch copper tee-fitting
  • 3/4-inch copper pipe
  • Additional 3/4-inch copper fittings (as needed)
  • Plumbing soldering equipment (if required)
  • Copper flex pipes (if needed)

Instructions For Installation Of New Water Heater Expansion Tank

  1. Shut off the water supply to your heater. If your unit is electric-powered, turn off the power supply. Open the drain valve of the tank to release the pressure.
  2. Look for the line of the cold water delivery pipe and disconnect the tube from the water heater.
  3. Using the pipe-sealing tape, wrap it around the entry port of the cold water pipe and the top thread union, then attach the copper adapter to the block.
  4. Tighten the adapter using the pipe wrench or channel-lock pliers and attach short-length copper pipe, add tee-fitting, expansion tank pipe, and expansion tank.
  5. Connect the cold water delivery pipe to the top outlet of the tee-fitting. Don’t forget to test the operation by connecting the hot-water line to the water heater, turning on the water source, turning on the water heater, and looking for leaks.

Variations For An Existing Water Heater

Look for a space to place your expansion tank. Since space is limited, adjustment on threads and fittings sizes will be the best thing for you to do. Sometimes it requires copper flex lines to be replaced with shorter or longer sizes. Moreover, additional fittings like elbows, threads, or pipes must be attached to cold water pipes. While connected to the cold water delivery pipe, the expansion tank should be one or two feet away from the water heater. Furthermore, some plumbers use a new dielectric union when adding an expansion tank to the existing water heater.

How Do I Know That The Expansion Tank Is Working?

Check the temperature. Touch the lower and upper parts of the tank. Usually, the lower part of the tank holds the heated water. Thus, this part is warm, and the upper is cold as this part has cold air. Test the sound of the tank. Gently hit the top and bottom of the tank. If it sounds hollow, the tank is in good condition, but if it thuds, its diaphragm is damaged. 

Seek Expert Help!

Installing a hot water heater expansion tank is best handled by a professional. It’s a fairly involved job that requires some specialized tools and knowledge of hot water heater plumbing. Scott’s Plumbing is a full-service plumbing company ready to help you. We offer free estimates, and we’ll give you a breakdown of the cost of replacing your hot water heater expansion tank.

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