[52mgtd]

The march pump works fine at lower temperatures but during three recent brew sessoins the pump feeding sparge water at 180 (high for heat loss) stops pumping after a few seconds.  The first time this happened, I  took the pump apart and a piece of grain came out.  OK, the impeller got stuck.  The second time, there was nothing in the impeller housing.  The third time I did nothing but ran a cleaning solution through it at teh end of the brew and it worked fine at 110.  Any thoughts?

[bonch]

You have to remember as the temperature goes up the more air you have in the water you are pumping due to the steaming of water.  Normally this isnt a major problem if you have plenty of head above the pump.  However if the discharge water source is not much higher than the pump itself you can start getting cavitation of the pump where it gets steam bound and will stop pumping.  Try putting the suction source higher or the pump lower and see if this doesnt fix your problem.

[svejk]

I agree - my only thought has to do with bubbles somehow getting into the housing, but that usually just happens with boiling liquids. Since the pump is not self-priming, I always make sure my pump is significantly lower than the kettle and watch out for bubbles.

[euge]

This is helping me alot also. I've had significant difficulty priming the pump when boiling. Then have to drop and let fill the return line all almost the way for it to start. My pump is about 20" below the bottom of the kettle and each hose is 6 foot. My suspicion is too much hose between the pump inlet and kettle at this height.

[bluesman]

I have also had issues with my March pump stopping after a short period of pumping.  I think there is air that is somehow getting into the line and causing the pump to cavitate.  Although I am not 100% sure of that.  This is not rocket science...what else could it be. 

I did have a loose conection at my kettle that I fixed so hopefully this resolved it.  I'll let you know next week when I brew my next batch.

[andyi]

I have had the same problem with running boiling wort thru the pump to sanitze it the last 15min of the boil and sometimes after flame out.  I am going back to a "relief" valve on the out end to purge the air.  It does not work every time for the boil but works great after flame out. 

I also carry a lot of hose 

Cheers

[narvin]

Check your hoses... you might need clamps to prevent air from being sucked in.

Also, where is your sparge water coming from?  If it's a sealed chamber, you need to vent it to allow the water to flow freely from it.

[bluesman]

Check your hoses... you might need clamps to prevent air from being sucked in.

Also, where is your sparge water coming from?  If it's a sealed chamber, you need to vent it to allow the water to flow freely from it.

This was taken from the March Pump 809HS manual.

 "The pump housing should be installed with the arrow on our housing pointing in the direction of the water flow within the system. If the arrow indicating water flow is not in the direction you require when the motor is in position, remove the four round housing screws (Item 1) holding the housing to the motor assembly and rotate the housing assembly as required."

http://www.marchpump.com/documents/Part%20Sheets/Hydronic_Pump-Series/0809-0053-1100.pdf

[klickcue]

Just a short take:

Are you taking pressure drops through check valves or other obstructions?

[denny]

I have had the same problem with running boiling wort thru the pump to sanitze it the last 15min of the boil and sometimes after flame out. 

I had the same problem until someone suggested to me to throttle back the pump output while recircing the boiling wort.  After I get the pump primed, I close the valve nearly all the way and it seems to work fine for me.

[bluesman]

I have had the same problem with running boiling wort thru the pump to sanitze it the last 15min of the boil and sometimes after flame out. 

I had the same problem until someone suggested to me to throttle back the pump output while recircing the boiling wort.  After I get the pump primed, I close the valve nearly all the way and it seems to work fine for me.

I'll give that a shot Denny.  Thanks.