Code or no code, manufacture requirement or not, I believe use of the CSC (Common Sense Code) applies here. We all know there are hundreds and hundreds, if not thousands, of codes and requirements. I haven’t met a HI yet that knows them all. With that said, I resort to common sense tactics.
In this case, if the buyer were standing next to me and asked:
Hey, shouldn’t that hood looking thing be screwed in ? If I happen to know the code (if there is one), I’d state it to the buyer. If I didn’t know the code (and if there is one), I’d tell buyer:
I don’t know of a code or requirement, but yes, I do believe you are correct, it should be screwed in and attached properly. Why do you ask ?
Well, if something were to bump into it, it could possibly knock the flue pipe (and hood) off from the water heater, …. And if that were to happen, you would have a whole lot of carbon monoxide coming out and into the house.
Even if there was no code / manufacture requirement, I’d still recommended to the buyer (seller) that the draft hood should be screwed in and/or attached properly. Some of the hoods I’ve seen, such as the one in my house, has a screw on one leg, and holes in the WH to insert the other three legs into (thus making for a semi-secure attachment).
That's my 5-cent opinion ....
