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Thermal Expansion and Your Plumbing

Thermal Expansion and How It Affects Your Plumbing

Thermal expansion takes place every time your water heater heats or reheats water. The dangers of this kind of expansion is when you heat an object in a closed environment/space you must predict and manage that expansion. For example, a helium filled balloon is filled in an air-conditioned store in the summer time. It’s filled and looks great. You take that balloon out to your car place it inside and go into another store. You come back and that balloon has popped. The gas inside the balloon heated, expanded and broke your balloon.


How does it apply to your plumbing system?

The growing trend in residential, commercial, public or municipal supplied water systems must have a check valve to eliminate the possibility of water returning to the public system from your water system. Many municipal water suppliers are systematically replacing older water meters with new electronic meters which contain check valves to update their systems and protect the public supply from back flow.

This creates a “closed water system”. Once you create a closed water system you must think about thermal expansion.

If your water heater is cold with 50 gallons in it and you turn it on to heat the water, the water inside when heated from 60 degrees to 125 degrees will expand by approximately 2%. Now 50 gallons of water wants to take up the same space as 51 gallons. If you have a closed water system (with a check valve on the water main) you essentially have nowhere for the water to expand to. This unmanaged expansion results in an extreme increase of pressure. Here is where you hope there are no failures in your piping or fixtures. thermal expansion

Managing thermal expansion is quite simple and far cheaper than a ruptured water heater or burst supply line flooding your home. A Thermal Expansion Tank can be installed on any cold-water line within the building but, preferably closest to the water heater. Patriot Water Heater prefers to install Thermal Expansion tanks on the cold-water line which feeds into your water heater after the shutoff valve.

The Thermal Expansion Tank is a wear item, a replaceable part (think about the brakes on your car). Thermal expansion tanks come in various shapes, sizes and configurations which is the job of a knowledgeable plumbing mechanic to determine the appropriate one for your system. The expansion tank when installed properly should operate without issue approximately for four to five years. We regularly check pressure and operation when maintaining or inspecting a clients’ home or business.

The average life expectancy of a water heater is between eight and twelve years. You should expect to replace the thermal expansion tank two times during the life of your water heater. If failure were to result to the thermal expansion tank and went unresolved you should also expect that you may also have a failure of the water heater, piping or supply lines due to increased operating pressures in your system.

If your water heater leaks and is still under a manufacturer warranty you should expect a manufacturer representative or service provider to assess the total installation of the water heater. If you have a closed water system and no expansion tank you can also expect not to have your water heater covered under warranty.

With the importance of using a reliable, reputable, professionally trained plumber or mechanical contractor who knows and adheres to plumbing safety codes and manufacturer installation requirements is of the utmost importance. You likely spent hard earned money having that water heater installed at some point in the past, don’t let it go to waste.

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