The NPTF to CPVC socket fittings should be wrenched tight to the pipe nipples in the water heater. Follow the instructions on the cement and primer cans. The ones I have used want the primer to be wet when applying the cement and immediately making up the joints. There is also an all in one glue for CPVC pipe that is both primer and glue in one step. Purple primer is the most awful staining stuff known to mankind. It has supernatural powers to damage the most expensive and difficult materials to replace. Don't ask me how I know that. Overall not a bad job for a first timer. Remember KZfaqland, Be kind.