Hot Water Heater Venting

Came across this today and not sure what to make of it. It appears to be some type of a damper. The metal box is open at the bottom and it looks like some sort of a damper inside. Although it does not seem to open or close. Is this some type of a air intake? Notice there is no bonnet on top of the water heater.

Why is there no draft hood on the water heater?

Exactly! Looks like a Do It Yourselfer…

Is it possible that the metal box acts as a draft hood? Never seen this setup before.

If the base of the box is open, the carbon monoxide will come right back into the room…
Also, where did the TPR valve extension go? Was it in the wrap insulation? Missing shutoff valve. It all looks like DIY work.

The 2 into 1 “Y” connection looks like a DIY job as well.