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How To: Increase Hot Water Capacity

Watch How to Increase Hot Water Capacity on YouTube.

Watch this step-by-step guide for installing a Cash Acme Tank Booster PRO Thermostatic Mixing Valve (TMV). This TMV extends the life of your water heater, and using other solutions within RWC’s family of brands, installation is fast, easy and reliable.

Tank Booster PRO is designed to double your hot water capacity by using source-point temperature control. With it, you can set the tank to 140°F, which destroys bacteria like legionella, and the valve will mix cold water to meet an anti-scald output of 115°F to 120°F. 

The Tank Booster PRO kit includes:


 1. Prep work

Before installing the Tank Booster, locate your power source and shut off the power to your water heater. Then, locate your main water source and shut off the water to the house. To drain the system, use the lowest water source in your home. This is usually your boiler drain at the bottom of your water heater.

Next, cut the pipe to disconnect the hot-water outlet and cold-water inlet on your water heater. Ensure the cut is even and the pipe is free of debris or sharp edges. To avoid electrolysis, check to see if you are joining any dissimilar metals. Review the Tank Booster PRO spec sheet and compare materials to your water heater inlet and outlet threads. When the metals are dissimilar, use dielectric unions with Teflon tape to create a seal.

 2. Connections

Once your galvanized nipples are installed, use Teflon tape to connect the adapter to the hot water outlet. Then, connect the Tank Booster to the adapter, ensuring it is connected to the hot water side.  

Thread the tee onto the cold-water inlet, ensuring that both the threads of the mixing valve and the cold-water tee are facing the back of the water heater to allow easy installation of the hose. Next, thread the water heater connector to the mixing valve and cold-water tee. Then thread the temperature gauge onto the hot-water outlet.  

To connect the cold-water inlet to the existing pipe, use a water heater connector like the SharkBite Max brass push corrugated water heater connector with ball valve. Use a SharkBite hot water heater connector to thread one side onto the hot-water outlet. With the push-to-connect side, push the connector onto your existing pipe using the same methods as the cold-water inlet connection.  

 3. Post-Install Adjustments

Tighten both the hot- and cold-water connections and ensure all fittings are secure. Then, let all the air out of the water heater tank by first turning your main water source back on very slowly.  

With all faucets off, slowly turn the water on using the ball valve on the water heater connector and once you hear that the tank is full, turn the ball valve handle back to its original position. Check that all the joints of your fittings are dry to ensure there are no leaks.  

Next, let the air out of the system using a water source that does not have an aerator, such as a tub. Run the tub for a couple of minutes to let the air out, then run another faucet to check that the air is out of the entire system.

Then, adjust the temperature of your water heater elements and thermostat to 140° F each. After setting the new temperatures on the water heater, turn the power on and adjust the temperature to 120° F on the mixing valve. Turn the Allen wrench counterclockwise to increase the heat and clockwise to decrease it.

Check that water is running through the temperature gauge and when the water reaches 120°F, tighten the locking nut using the Allen wrench and ensure the temperature remains constant. 

Tank Booster PRO