You might be closer to a giant bomb than you think.
Right in the middle of most homes is a water heater. When not maintained properly, these systems are dangerous time bombs waiting to explode.
Water expands under extreme temperatures, causing dangerous amounts of pressure inside water heater tanks.
In this case, water heaters and boilers should have an expansion tank to minimize the damage to closed heating and plumbing systems.
How does a water heater expansion tank work?
Hot water heater expansion tanks are designed to regulate pressure and maintain the structural integrity of your water heater.
Dangerously high levels of pressure damages the water heater, plumbing fixtures, and pipes. This is a serious hazard, especially since pressure build-up can cause water heater systems to blow-up.
An expansion tank is basically a safety device that also increases system efficiency and life expectancy, effectively cutting your water bill and repair expenses.
Expansion tanks work to minimize stress by absorbing excess water supply volume and pressure.
Due to thermal expansion, water expands about 2 percent as it heats from 50 to 120 degrees Fahrenheit. This causes the water supply to apply constant pressure on the water heater receptacle as it increases temperature.
Water heater expansion tanks have two sections separated by a rubber diaphragm. These two parts work together to equalize pressure throughout the water heater system:
- Water Section
- Pressurized Air Section
One part is connected to the pipes of the water heater. This is where water flows through.
The other section contains dry, pressurized air at approximately 12 PSI.
As water flows through the water portion, pressure increases within the system. This pressure causes the rubber diaphragm to be pushed away, and excess water easily streams through.
This effectively relieves the excess pressure in your heater system, preventing damage to pipes, connections, and the water heater itself.
Do I need an expansion tank?
The answer will depend if your water supply system is “closed” or “open.”
Open water supply systems will not usually have a problem with thermal expansion. Tankless water heaters also do not have the problem of pressure build-up.
On the other hand, an expansion tank necessary for a water heater in closed systems. These usually have a one-way valve.
Installation of a one-way valve such as a check valve, pressure-reducing valves, or backflow valve will cause dangerous thermal expansion that can cause significant damage to your water supply system.
What will happen if my water heater doesn’t have an expansion tank?
The good news is that water heater failure due to high pressure will usually have many warning signs. This includes: water leaks and rapid deterioration of plumbing fixtures.
The most vulnerable parts of the plumbing system include supply lines and toilet, laundry machine, and dishwasher valves.
How to Install a Water Heater Expansion Tank?
While it’s also a good idea to call a professional plumber, expansion tank installation is generally simple and easy. An experienced DIY-er can get the expansion tank up and running within an hour.
Here are the steps and some important tips for installing diaphragm tank:
- Cold Inlet Line
- Installing at an Angle
- Expansion tank Sizing
Remember that it is best to install the expansion tank on the cold water line before water flows into the heater.
This effectively reduces the pressure from running faucets and toilets, which can damage water fixtures in the long run.
While most retail expansion tanks will recommend installing at a vertical hanging position, tanks can be installed at almost any angle.
Retail expansion tanks will usually come with a saddle fitting and threading equipment that eliminates the need for complicated soldering. These types of fittings are generally unreliable.
Soldering using the proper fittings and galvanized materials will allow for much more flexibility and sturdiness in the system.
Expansion tanks range from around 30 to 200 USD for residential tanks and up to 1,000 USD for commercial purposes. Pricing depends on the size of the water tank.
For most residential and domestic expansion tank sizing of 40 to 50-gallon water heaters, a two-gallon expansion tank is more than enough.
What causes an expansion tank to fail?
Various factors will determine how long your expansion tank will survive wear and tear. These include, but are not limited to: tank quality, proper installation, and water quality.
Most tanks have a one to a five-year warranty, so it would be best to find a replacement tank every two to six years.
Damage and leaks are commonly caused by:
- Wear and tear of the rubber diaphragm
- Corrosion between piping and expansion tank
Expansion Tank Maintenance
Once you have your expansion tank installed, make sure that you regularly inspect the system.
For more advanced testing, make sure to contact a licensed plumber.
When maintaining your expansion tank, make sure to ask yourself these important questions:
How do I properly monitor my expansion tank
There are multiple ways to check if your expansion tank is in working condition.
Any homeowner can do these three preliminary tests before calling a professional plumber:
- Visual Inspection of Pressure
- Touch and Tap test
- Check Valve
One of the simplest ways to monitor your expansion tank is to visually observe water pressure. A faulty expansion tank will cause water pressure to fluctuate depending on water temperature.
If hot water initially runs with high pressure and gradually weakens, this might be a sign of expansion tank failure.
While this is a very simple and convenient method, it’s not the most reliable one.
You can also check if your expansion tank is working by manually checking the temperature of the device.
The top section should feel warm, while the bottom section stays at room temperature.
If the whole system is warm, it is likely that hot water has flooded both sections due to diaphragm damage. In this case, expansion tank replacement is necessary.
Alternatively, you can also test your expansion tank by tapping the two sections with a metal object. The section for air should sound hollow, while the section for water should sound dull.
A reliable way to monitor your expansion tank is by testing the check valve.
Try opening the valve on top: air should be released. If water leaks out, it’s likely that the tank is damaged.
In the case that your expansion tank fails these tests or if you notice any corrosion on the tank, contact a professional plumber immediately.
How do I prevent expansion tank failure?
First of all, ensure that a licensed plumber installs the tank for you. Skilled professionals will ensure that the tank is properly supported and connected.
Another way to prevent expansion tank failure is to invest in a quality tank in the first place. A long-lasting solution to your thermal expansion problem is a tank with a five-year warranty.
These expensive yet reliable tanks are made from sturdy stainless steel and high-quality materials.