Quote Originally Posted by Schuimpge View Post
Although it's always good to have union-valves to be able to take parts of the system out if they fail, I don't think they're necessary for Norton's setup with regards to cleaning maintenance.
There's a 3-way valve on top with 3 pipes. Without knowing the specs of the filters, I'm pretty sure that's:

1. Water Inlet
2. Water Outlet
3. Backwashing/cleaning outlet

The valve settings would then be: Open/Closed/Backwashing.

Cheers,
Luc
You're right about the 3 connections (in/out/backwash). These types of filters, apart from regular backwashing, need to be topped up occasionally with whatever medium is inside (carbon etc). Without unions in place to disconnect the pipework to the control head, you would need to cut the pipes to unscrew the head fromt he filter body. Also good to have valves in place to isolate the filter.