Jared

As I do agree with a good portion of what Jerry says I also have great faith in tradesmen if approached properly. Yes many plumbers will screw it up. The other half will do it right.

However. If you press them on it and literally have them show you the proper instalation by the newest code (and that is what you should go by where you are making changes) then the likelyhood of screwing up is extremely minimised. After all you appear to be doing this yourself. If you know a plumber or even consult with a plumbing company, press the on proper instalation for todays codes. If they are not doing the work they a not likely to cheat or ignore proper installation.

As I also mentioned. It depends on where in the home the water heater is. Or more to the fact of where it is drawing combustion air from and where or what room it will be possibly venting to. Way to much going on with water heaters or heating units and their combustion and or ventilation to get hits from this or any site. There mmay be factors in your home that might not get conveyed.

Ventilation of any type of fired unit is not something to take litely. After all it is you and your families lives at stake. Don't mess up.