When is an ASME rated expansion tank required on a domestic water system?

[nuuvox000]

I've heard all the rules of thumb, over 30 psi, over 15 psi, if it's connected to a boiler system over 200,000 BTU/hr or over 120 gallons, etc. But I just can't find any actual code section that requires this. Can someone please point this out to me? Thanks!

 

[LittleInch]

This looks more like a state by state boiler code issue not an ASME VIII code issue.

Found this fairly easily

https://www.deppmann.com/blog/monda...rmal-expansion-tanks-asme-label-requirements/

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[HVAC-Novice]

Check out the boiler code in your jurisdiction.

Where I'm vessels for water treatment and conditioning don't have to be ASME rated. But an expansion tank has to be. But this is specific to our State boiler code and I had to ask JHA to get clarification since I traditionally had used ASME chemical feeders. So, you really have to research YOUR code and talk to YOUR JHA. And no, it doesn't make sense to me why some items need to be ASME, some don't. But it is what it is.

 

[LittleInch]

Have you asked local vendors or installers?

Which state?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[PEDARRIN2]

In my state, it also includes systems exceeding 180 F, which is not usual for domestic type systems.

 

[dbill74]

607.3 Thermal expansion control. Where a storage water heater is supplied with cold water that passes through a check valve, pressure reducing valve or backflow preventer, a thermal expansion control device shall be connected to the water heater cold water supply pipe at a point that is downstream of all check valves, pressure reducing valves and backflow preventers. Thermal expansion tanks shall be sized in accordance with the tank manufacturer’s instructions and shall be sized such that the pressure in the water distribution system shall not exceed that required by Section 604.8.

Unless the location of the installation is following a different code, in which case you need to search through that code.