Greetings
@LukeClaydon, and welcome to the forums at Homebrewtalk!
I had to look up "VWP solution" as it's not anything commonly referred to here. As it is a chlorine-based sanitizer I would be careful about prolonged exposure to stainless steel in general - chlorine is stainless steel's Kryptonite and can literally eat its way through kettles and kegs.
And as it turns out chlorine is not great for copper, either. It's corrosive, and copper is one of those soft metals that can be chewed up by pretty much everything.
So...given a thorough rinsing (I would use the hottest tap water you have) on both wort and water channels I would not be concerned health-wise, but would then want to do a reasonable pressure test to see if any of the plates or copper brazing have a breach: put your domestic water pressure on one side, make sure that channel is full of water, then cap the exit, let it sit overnight in a sink, and see if there is any water flow in the opposite channel.
Alternatively find a way to hook up a compressor to one channel, put something like 20 or 30 psi on it, and see if the other channel is "passing gas" (cap one end and run the other end into a jug of water.
I would think you'd only need to pressure test one channel as the plates only have two sides
Cheers! (and good luck!)
