question on orphaned water heater

sorry for the double post, i didn't reslize this forum had a specific board for water heaters....



you guys are the pros and hoping you can hep me with this issue....


had a home inspection done on a house we are looking to buy, turns out owners put a new direct vent furnace in 6 months ago so basically the water heater is only gas appliance venting through original chimney now. There was no liner added either. How do I know if this is ok or not? from what I understand there could be issues b/c the current flu is most likely too big to just vent water heater alone and can cause some negative pressure issues?


Lastly the water heater is 14 years old so I am trying to get owners to replace it with a direct vent model based on it's age as well as how it is currently venteed now.......


owners are saying that it is a functioning water heater with no issues... Is there any code when it comes to orphaned water heaters?


any help is greatly appreciated.


regards,

harvey

There may be issues with the longevity and suitability of the flue with the diminished exhaust volume. Is this a brick lined flue, or what?