Hi guys, I have a question about if a water tank can not be connected with c vent since this year the code book is changed?
You can still use C-vent as a vent connector.
If you look in the installation manual, the water heater is most likely classified as a Category I appliance. Refer to Table 8.5 in the Gas Code.
Listed equipment with draft hood = chimney, special venting system.
QuoteSpecial venting system — a venting system certified with the appliance and either supplied or specified by the appliance manufacture
You would probably be using Table C.2 or C.4 to size the vent capacity. As long as you had the capacity there is no problem.
Also make sure your vent connector does not exceed the limits specified in Table C.9.
Even if you had to use B-vent for the vent connector, you would still be connecting a C-vent to B-vent adapter on the draft hood.