Plumbing connections on the boiler wall

[Richj]

Hi all, I have a question for all the Diy people. Buy my Hoover electric water heater is two water connections. The one on the left cold water in to the heater. The one on the right domestic water out of the heater which are both connected to the wall connections, which has 3 unions. What is the center connection/Union used for?. I also have 3 plumbing outlets under the sink, and the center one is blanked off. Any ideas Hope you can help.

[Richj]

Yeah that is quite correct. But my question is... Where is the center connection in the wall connected? Is it used as a drain in case the boiler over heats. We don't have this arrangement in the uk.

[Richj]

Yep that makes sense then. I blew down it and it was not connected at the other end. Looking at the diagram supplied with the boiler it does require a drain in case the boiler develops an over heat fault. Thanks for info. The forum delivers again, cheers!