March pumps not priming.

Any idea why these pumps are hard to prime. They seem to get air on them. I have to unhook the lower fitting run them for a bit to get them going. I thought if they were mounted like this they would work better.

 

For one, they're mounted upside down. You really want the outlet at the top so that the air pocket that forms gets pushed out of the pump, rather than through the pump causing cavitation. You might also consider installing a bleeder valve just after the pump outlet to help with priming.

 

Yep, upside down. You don't have to remove the pumps; you can remove 4 bolts and rotate the pump heads. Unfortunately, it looks like you'll need to make a couple of new lines to reach the pump inlets at the bottom.

 

Well Crap! I thought you would want the help of gravity to prime the pumps. Guess my thinking was wrong! Thanks guys!

 

You do, but gravity will still do its job as long as the pump is lower than the kettle.

 

Additional info here..... http://www.homebrewtalk.com/f51/march-pump-mounting-330217/

 

This was my fix. I have not tested it and I still need to shorten the return hoses.

 

According to the March Pump Manual, you do not want any elbows or restrictions within 8" of the inlet.

Use a longer loop of hose going into the inlet of the pump and get rid of the elbows..

 

One thing I have done is add priming valves to my outlets. This has greatly simplified the effort to get things moving. When you are ready to start the pump, open the priming valve to bleed any air out of the pump, then once you have good flow, close the priming valve and everything should start moving where you want it to. I catch the output in a small bucket so I can add it back into the batch.

Please excuse the foil heat shielding.

 

The actual wording from the March pump General Installation Instructions is:

"Install the pump as near to the suction source and as low as possible. Suction must be flooded. When using an elbow, valve, etc., the suction must have straight piping in length at least five (5) times the diameter of the pipe."

Left unclear is whether the diameter of the pipe is the inside or outside diameter, but I'd think in the context of the discussion it would be the inside diameter, which would make the minimum straight length pipe into the Intake side of the pump head closer to 3 inches than 8...

Cheers!

 

Either way, it is not a good thing to have an elbow directly connected to the inlet of the pump.

Cheers!

 

I have 3 inches or less on my system. I go from a street elbow to a nipple to a coupling to the pump - about 2 1/2 inches from the bend in the elbow to the pump inlet. The inlet has a straight run of maybe 1//2 inch before meeting the main body of the pump head, so perhaps a total of 3 inches straight from the bend. The only priming problems I had were when I had a dip tube in the kettle - I had priming problems when the water in the kettle got near the boiling point. I took out the dip tube and have had no more problems.

 

I've seen these on a lot of setups... but wouldn't they leak wort? I'm designing a basement eBrewery and just dumping wort on the ground is not an option for me.

 

They put out a little of whatever you're pumping, but it's only a couple oz. I run mine into a 1 Qt paint can, and just dump whatever water and wort it's collected at the end of the brew day.

 

No, it's a valve. Typically, you only need to prime them once. I stick a short hose on the outlet, catch the wort or water in a small bucket, depending on the side, and put it back in the system.