Does restricting a pump on the out / downstream side damage the pump? I've read that you don't want to close any valves on the in / upstream side. I need to slow the pump flow during mash recirculation as the wort is coming out of the bottom of the kettle faster than it is making its way through the grain bed.
I guess my question is: Does throttling the pump have any adverse effects on the pump or its lifespan? If I run the pump for 40 minutes this way during the mash will it wear out prematurely?
I can't see restriction on the up or down side making a difference in terms of pump life; I'm curious to see what others have to say. I do agree that dry would be a bad thing for the pump. Therefore, regarding your question will your mashing be closed loop or open? If closed, running dry is much less of a concern; it would take a clog in the system to run dry. However, if you're sparging for 40 mins as an open loop, you're going to want to watch that your flow in is equal or greater than the flow out.
Centrifugal pumps like a march or Chugger can be run with the throttle on the output closed with no problem. I run at a trickle when sparging for 45 min. The pump is >10 years old. Edit, on the inlet throttling will cause cavitation, which is bad for the pump.
