Clearance for venting

New construction
What is the clearance for two hot water heater power vents from each other? Currently they are next to each other
2 furnaces, the combustion air and exhaust are right next to each other. What are the clearance requirements?
O and the township inspectors didn’t say anything.

Do you have the model numbers of the heaters?

I’d look up the installation instructions using the appliance model numbers. This will be specific to the make and model.