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a code that's new to me

ICE

ICE

Oh Well
Joined
Jun 23, 2011
Messages
12,922
Location
California
I didn't know this until today. Almost all pressure relief valves have a bypass back to the supply which was considered reliable to relieve excess pressure and therefor an expansion tank wasn't required. I now have a water heater company that installs an expansion tank whenever there is a pressure regulator.

608.2 Excessive Water Pressure. Where static water pressure in the water supply piping is exceeding eighty (80) pounds per square inch (552 kPa), an approved-type pressure regulator preceded by an adequate strainer shall be 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.

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Not all pressure reducing valves have a bypass built in. Watts will have a "B" in the valve nomenclature. If the municipality uses a water meter with check valve in it to prevent back flow the bypass will not function,also mineral deposits can form inside the valve preventing it from functioning. The thermal expansion tank is the best method. Watts also makes a ball cock that will relieve the thermal expansion into the water closet.
 
There is a company that does nothing but water heaters and all of the sudden I have been finding an expansion tank at every water heater. The customers ask me if the tank is required because the plumber told them that the code requires it. So I called the company and spoke to the owner. I had other questions besides the expansion tanks and this guy is a wealth of information. As a matter of fact, he is now a go to guy when it comes to water heaters.

I haven't been able to confer with my chief plumbing engineer but at this point I am inclined to think that an expansion tank isn't required when a water heater is replaced or even if a pressure regulator is replaced. Now if a pressure regulator is installed where there was none before, an expansion tank is required.
 
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The code requires a thermal expansion tank when located on a closed system ----- newer water contamination restraints are placing backflow preventors in the newer water meters..... thus creating a closed system in newer construction.

In installations, it has to meet current code, thus it is easier to install the thermal expansion tank than trying to look at the water meter and find out if it has a backflow valve or not...
 
The policy has been established that replacement water heaters or replacement pressure relief valves will not trigger a requirement for an expansion tank.
 
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