In a previous post I had sung the praises of our workhorse brew pump. Check her out now!
While the pump had always been an awesome tool in our brewing arsenal, up until now it has left much to be desired in its ability to achieve and maintain prime. As such we would constantly have to disconnect and reconnect hoses, often spewing boiling wort or water all over the place. At best this would leave us with a very sticky floor. At worst, second degree burns to the hands and arms. Either way, this kinda sucked.
As such, we made a few changes to our pump plumbing, and I for one could not be happier with the result.
First, we reconfigured the pump head to a vertical alignment with the intake at the bottom. This makes it much easier for air bubbles in the line to vacate the system. Less air in the lines=easier prime. Secondly, we added valves for each of the intake ports. This gives us much more control over the flow of liquid and also seems to drastically reduce the amount of air that finds its way into the system.
The end result? A much more efficient brew process and a lot less mopping.
Regular Guy Brewing 
How sensitive is the pump to prime? I know not to run an empty pump, but will it cut out or stall if it is not primed? Will it operate in a degraded state? Also, if my brew kettle is high enough, and my pump in and out are oriented horizontally, should I shift it so that the in is facing downard?
The pump can be a bit touchy to prime. You have to have fluid running through the head to run it. If you don’t, it will not cut off or stall, it will just cavitate and make an ungodly racket. This is not only extremely annoying, but it is dangerous as it can burn out the pump. Which is bad. When we were initially learning the ropes with this pump, one of us were never too far from the power cord, ready to shut it down at a moment’s notice. Once you get the hang of it it though, it’s a very easy piece of gear to operate.
As to whether it will operate in a degraded state, I don’t really know. To be honest, I’m not sure I understand the question. It’s either full prime or nothing.
Regarding your brew kettle height, if the pump is low enough below the kettle you might be okay with a horizontal orientation. That’s how we did it for the first half dozen brews, with the kettle output only about a foot above the pump. But even with this orientation, you do have the opportunity for air to get caught in the pump head. I have no idea how so much air gets in the system, but I have come to the conclusion that it is an inevitable fact of brewing. Once you get any air in the head, you are opening yourself to issues. Nothing that can’t be fixed, mind you, but you do have to be fairly vigilant. If this happens, you may have to re-establish your prime. Depending upon what steps you have to take, this can either be a minor inconvenience or a big mess with possible first degree burns.
That’s why we switched to a vertical head orientation with the in at the bottom and the out at the top. Any air pockets that comes into the head escape out the top valves, instead of getting stuck inside. Once we have our initial prime, we are set for the night. No more spills. No more burns. No more messes.
That said, if you have the means to do it, I can not recommend the vertical orientation highly enough. It has been a huge time saver for us, and I have no doubt that this one simple change has prolonged the life of our little workhorse.
Hope this helps.