Proper Venting of Multiple Gas Appliances

I was wondering if anyone could tell me if this flue setup is an issue? I know that for separate flues, the smaller appliance should enter a common flue or chimney at a higher point than larger appliance. I am not sure for a manifold setup, does that make a difference what order the appliances go in before connecting to the main flue. Also, shouldn’t there be separate barometric dampers for each appliance?

Looks like a home depot parts job to me, not sure why a barometric damper is needed at all, as they are all gas appliances and have draft hoods, the water heater or boiler on the left could go in the bottom of the chimney instead of looping around like it does, it may not be wrong by your local AHJ, but I would refer that to a qualified gas fitter person all the same.

Thanks, That’s my take on it. My concern was possibly the draft from the larger boiler interfering with getting a proper draft for the hot water heater.