Water Heater Expansion Tank Installation

All the water supplied in homes is usually contained in a centralized underwater tank. From there, the water is then distributed to homes all over the neighboring regions. However, basic physics tells you that when water is heated, it expands, as mentioned in Rheem tankless water heater reviews.

Normally, in older homes, the expanded water used to push back into the water main or the individual homes themselves, causing a backflow of pressure.

However, most homes today have backflow prevention valves which stop the water in your home from reentering into the water supply. These valves can be placed inside water softeners, in the pressure regulating valves or on the water meter itself.

Once again, the expanded water now has nowhere to go and the water pressure in the house's pipes can increase dramatically, most times to the point where the pressure valve discharge pipe starts dripping.

What’s a Hot Water Expansion Tank?


This is where the thermal expansion tank comes in. It has an internal air bladder which absorbs the expanded water and protects your precious plumbing, appliances and the water heater. For basically these reasons, most homes now need a thermal expansion tank (and, most times, a properly adjusted pressure regulating valve). In fact, not having a thermal expansion tank is the most common reason for a dripping discharge pipe.

The water heater expansion tank installation usually happens close to a water heater and may be installed in any orientation. Internally, there’s a flexible diaphragm which divides the tank in two - the “wet” side, which creates a connection to the plumbing system and a “dry” side, which features a valve that allows the pressure of the tank to be adjusted as needed.

Water heater expansion tank installation – How to do it?

Nine out of ten times, the water heater expansion tank installation is done on the cold water supply of a domestic hot water tank, since here is where it’s’ most effective. The process itself is fairly easy and usually only requires a tee fitting to be added to the water line. Here are a few factors you need to consider first.

The Positioning

The first thing you have to do is decide where you want to install the water heater expansion tank. Obviously, the tank has to be installed between the cold water shut off and the water heater inlet, but you still have to decide where the tank itself will sit.

The Orientation

Most tanks will work regardless of the orientation. However, some orientations hold their own advantages. For instance, a tank installed vertically with the air side up and the tank’s bladder ever happens to fail, the tank may continue to function (albeit at a reduced capacity) until all the air escapes from the tank.

However, if the tank is installed with the air side down and the bladder unfortunately fails, all the air will immediately move to the top of the tank, and the tank will fill completely with water.

The actual process- Installing the water heater expansion tank

Now that you’ve decided where the tank will connect to the plumbing system, also being where the tank will spend the rest of its life, it’s time to start the actual installation of the water heater expansion tank.

1

Turn off the water

First things first, you have to figure out how to turn off the water heater, and then turn it off. Afterward, you’ll have to locate the cold water supply shutoff valve and turn the valve to off position. Finally, turn on the lowest hot water tap in the house. This will release any built up pressure, also preventing water from spraying out when you cut the pipe in the next step.


2

Mark and cut the pipe

Using the tee as a guide, mark the pipe where you’re going to install the tee then cut the pipe at the positions you’ve marked using a pipe cutter.

If you don’t have to cut the pipe, it’s safe to skip this step.


3

Install the tee

Solder, snap, or twist the tee into place and then install any extension pipes required to reach the tank’s final resting place.


4

Check the system pressure

At this point, you’ll want to close the faucet and open the shutoff valves. Turn on all the hot water fixtures in the house until water flows normally to ensure the system is filled and is at full pressure. Check for any leaks and repair them.

Attach a pressure gauge to any part of your plumbing and open the valve to get a reading. If the pressure is not within the normal range of 40 – 80 psi, you’ll have to take steps to correct it.


5

Pre-pressurize the tank

Almost all water heater expansion tanks come pressurized from the range of 12 – 40 psi, but before you install the tank you’ll have to match the system pressure. Start off by removing the protective cover from the air valve on the tank.

You can use a tire gauge to check the pressure and a bicycle pump, or compressor, to fill the tank and match the system pressure of the tank.


6

Mount the tank

Once you’re done, attach the tank to the plumbing, and mount it using your straps and/or brackets. Turn everything on, and then check for any leaks.


You’re pretty much done, so stand back and revel in your success. You know about the water heater expansion tank installation and you can tell others about it.

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