Long Running Times for Pumps

Is there any harm to a March 809 or LG 3-MD-HC from running it all night long? I'm thinking about mashing for a VERY long time, but don't want to hurt my pumps.

They are designed to be run 24/7 in recirculation situations, so I think you have nothing to fear.

You'll be fine, but can I ask why you'd mash all night long? (not that kind of mashing )

So I have just not had any time to brew lately, and have been looking for any way to get more brew days in. I originally started by thinking that I could mash for shorter time periods and just suffer with lesser efficiency, but then that got me thinking about mashing during the day or overnight? I do have a HERMS hooked up to a BCS-460. I would love to be able to brew on a weeknight and not go to bed at midnight, so here is the plan.

Day 1
Crush and measure grain
Before bed, setup my system to heat water to the correct temp by morning

Day 2
Wake up, mash in and start recirculation
Head to work
Before heading home login to BCS and set the system to mash out
Get home and batch sparge, boil, and finish the brew day

I figure that I could potentially be done by 8 PM with a 90 min boil and cleanup? I just didn't want to hurt my pumps by running them all day. I also don't want to let the mash drop in temp if I don't have to.

I wouldn't worry about the pumps. Not sure I would leave my rig unattended for that long though. A lot of things could go wrong. But, if your that confident...go for it.

If you wanted to get geeky about it, you could remote monitor with the BCS-460. You could rig a flow switch to trigger an alarm should something go afoul.