Water Heaters - Old house, new hot water heater

We just bought an 82 year old house. The water heater is located in what was an outside porch which has been enclosed. We have determined the gas water heater would better serve us by being relocated into what wll be an otherwise under-utilized closet which abuts an outer wall. Directly above the closet is a parapet wall. The roof is about a year old and we would like to avoid penetrations in a potentially problem area in the roof (parapet wall). There is ample room to vent the flue at 45 degrees through the outside wall which happens to be stucco. My questions. Does venting out a side wall seem reasonable? How much straight vertical rise, if any, should be allowed? I will check with city ordinance but any info would be appreciated.

Check with local codes.


If you go out a sidewall, you still have to go a certain distance above the roof line to create proper draw for the water heater.