Q: Only seen a couple of these around Chicago. Is this a code compliant exhaust cap? Was told it was because "rain kept blowing into the cap and dripping down the vent pipes."
It is for natural gas furnaces (second floor) that connects to an upper units venting (3rd floor) and then out.
A: Assuming it’s venting a category 1 appliance, no. At no point should a natural draft vent system slope downward. If the cap is leaking, get one that doesn’t. NFPA 54 section 12.7.2 -Gas Vent Termination - Tony3696
NFPA 54 section 12.7.2 -Gas Vent Termination
Page 229 has a pic of what is acceptable. It does not mention a U bend. - 33445delray