Hi GI,
Doing a similar redesign myself on the brewery as per another recent thread. I'm going to gravity feed to the kettle so I dont have to pump, I'm a bit nervous about that. I've only ever stuck once but I'm not keen to repeat so I'm going to stick with what works and is easiest.
Anyway, I noted a couple of things with your diagram.
Firstly, now I don't know if this was purely because you wanted to illustrate the pump in your diagram or what, but I noted your pump as being positioned vertically. If your diagram is correct and accurately shows how you were going to mount it, reposition the pump so it's horizontal. They are only designed to run when positioned horizontally (has to do with bearing placement and load). But I'm sure you knew that and it was just for illustration in the diagram.
Secondly, how do you plan to prime your pump? Do you have a bleed valve positioned after the pump (this is the most common method to allow the pump to fill)? If you have a look at a lot of systems most have a T-piece after the pump that allows you to crack open the valve and fill the pump. However, you dont have to do this and it looks like you might be able to use the recirculation loop to open and prime your pump. Or perhaps you plan to do it as I hope to (next paragraph).
I plan to connect all hoses in my brewery at the start of the session so they stay connected for the entire run. Then just redirect as you have planned with the valves. I'm hoping to get around the prime issue by filling all hoses with water before I mash in, that way I can recirculate and hopefully flush all air from the lines and prime my pump before I start, then by not having to disconnect any hoses hopefully I wont introduce any air to the system and wont lose prime on my pump. Lets hope it works
.
At a quick glance too, I think you could do away with that first valve after the pump-considering the two lines branching off after it both have valves on anyway, why not regulate the flow from these ones. No different and save you a ball valve.
Anyway, looks good so I hope it all pans out well.
Cheers, Justin