The municipal water supply for the house acts as a gigantic expansion tank… and nobody notices. This is illustrated in the diagram below. You have a closed system! One way for this to happen is to have a check valve installed on the water supply coming into the home.
The other way to create a closed system is to have a pressure regulator installed that contains a built-in check valve. Watch your pressure gauge to verify this. When a closed system exists on the water distribution piping in a home, an expansion tank needs to be installed somewhere on the plumbing system.
This is a simple and straightforward fix; an expansion tank will give the water somewhere to go when it expands, and the TPRV on the water heater will stop causing problems. Expansion tanks are required when a closed system exists, both by water heater manufacturers and by plumbing codes.
The Minnesota State Plumbing Code requires an expansion tank when a pressure regulator is installed An approved expansion tank shall be installed in the cold water distribution piping downstream of each such regulator to prevent excessive pressure from developing due to thermal expansion and to maintain the pressure setting of the regulator.
Additionally, Section A water system provided with a check valve, backflow preventer, or other normally closed device that prevents dissipation of building pressure back into the water main shall be provided with an approved, listed, and adequately sized expansion tank or other approved device having a similar function to control thermal expansion.
If an expansion tank is already installed and there is still a problem with excessive pressure, you have a problem with the expansion tank. Great post! Book Now. Call Us. Text Us. The Fix When a closed system exists on the water distribution piping in a home, an expansion tank needs to be installed somewhere on the plumbing system.
This rule also applies to hot water heating systems; when a boiler heats the water in a hydronic heating system, the expansion tank allows for the water to expand without the pressure relief valve leaking. If the pressure relief valve on a boiler system chronically leaks, even after replacement, it probably means there is a problem with the expansion tank.
Reuben Saltzman is a second-generation home inspector with a passion for his work. Naturally, this blog is all about home inspections and home-related topics in the Twin Cities metro area. Home All Sections. Log In Welcome, User. Coronavirus Minneapolis St. Paul Duluth St. Study: Mpls. Paul minimum wage increases led to loss of restaurant jobs. Protest outside Prior Lake High attracts hundreds outraged by racist video.
Suni Lee says she was pepper sprayed in racist attack in Los Angeles. Twin Cities will see snow, high winds — and more Up North. Pressure relief valves age and can begin to deteriorate, especially in factories and facilities where they encounter extreme temperatures and a great deal of wear. Over time, valves can become damaged, which affects their ability to close properly. If there is any damage or excessive wear to the valve seat or seal, leakage is likely.
Another common cause of safety relief valve leakage is when the valve is the wrong size for the project. The operator sets the percent of set pressure and the duration of the test.
When the operator starts the test, the AccuTEST system takes over, holding the valve at the appointed percentage of set pressure for the specified duration. While the system holds the valve at pressure, the operator is able to count any bubbles in the valve to assess its condition and determine whether the valve is leaking or not.
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