Postgres 9.4 and 9.5 on CentOS on same machine unix socket incompatibility

I had Postgres 9.4 installed on CentOS 5 which is listening on default port
5432 and everything worked fine when I wanted to connect using the unix
socket. Then I installed Postgres 9.5 (just installed it) and now psql
wants to connect to a different unix socket path:

/usr/pgsql-9.4/bin/psql -U postgres
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket
"/var/run/postgresql/.s.PGSQL.5432"?

The thing is that 9.4 doesn't create a unix socket in that directory, it
only creates it in /tmp. I think the problem is with all older versions,
not just 9.4.

How does 9.5 tell all other psql versions where to search for the unix
socket?

Strahinja Kustudić | Lead System Engineer | Nordeus