vCenter Heartbeat uses port 52267 as the default Client connection port. The active server listens on port 52267 for any client connection requests. Once the client has connected to the active server, the client and the active server will communicate using ephemeral ports, which are assigned dynamically from a range, and are valid only for the duration of the connection.
The following ephemeral ports need to be opened at the firewall.
Ports 1024 to 4999 for Windows 2003
Ports 49152 to 65535 for Windows 2008