I have a chimney in my house but no fireplace. There never was a fireplace, only a pot belly stove long ago that vented into the chimney by way of a vent pipe. The chimney is completely enclosed in the wall. Currently, my gas water heater's vent pipe 90s over in the attic and vents into the chimney. I called the codes office recently to find out if this was allowed since I am about to have my roof replaced. Trying to decide whether or not to dismantle the chimney above the roof or not. The chief plumbing inspector said it is allowed. I failed to ask him this, however. I will eventually call him, but thought maybe some of you would know. There is currently no vent hood in my kitchen. I plan to install one. Do you think I would be allowed to vent the piping for the vent hood into the chimney as well along with the gas water heater (which will eventually be replaced with a gas tankless water heater)? Is there any cause for concern in having a gas water heater and a vent hood vent into the same chimney?