Oval water heater vent

Is there an approved oval and/or wall stack water heater vent? Basement water heater vented up through exterior wall to the roof with an oval pipe.

Thanks in advance.

Yes there was a double wall class B oval vent used that was acceptable got any pics

No, it was in the wall. Could barely see it in the basement. Attic wasn’t accessible. I’m assuming the 1" clearance still applies, no? Seems like that would be hard to achieve in an exterior 2x4 wall.

Thanks for the reply.

Yes, 1 inch clearance, assuming it’s a listed BW-vent.

See page 22.
Maximum BTU input is:
Single Story = 85,000 BTU
Multistory = 65,000 BTU

Nice link Mr. Kage:D:D