Problems with the H315 : High Temperature Polysulphone Pump

[peterc]

I bought this pump a little while ago and I've been having problems with it since the first use. I'm using it to pump from my hot liquor tank into my mash bucket for the sparge but it seemed to only work intermittently.

I found myself going through some crazy voodoo dance to try getting it to work.

Lift it up, not working.
Flip it over: YAY! It's working! Oh wait, no it's not.
Lower it again. Now it's working.
Uh oh my temp has dropped. Fire that up again.
Crap, now it's not working.
Maybe if I shorten the lines, hold it in my left hand, and stand on my head it will work. But that thing's hot from that 170F water pumping through it and while I'd sacrifice my left hand for good beer it might be safer to ditch the pump and balance a bucket of hot water on my head and let the gravity feed the water into the mash.

I managed to save the beer by the way so it's all good. And the doctors say these burns will heal with only minor scarring. But the important thing here is that I learned something interesting while researching the cause of all of this.

170 F.

That's a magic number. It's the temp I've always been told to sparge at. It's also the temperature magnets stop being magnets.

http://www.rare-earth-magnets.com/magne ... ts_FAQ.htm
(look for the "Will my magnets demagnetize if I heat them?" question)

As it turns out (I took the pump apart) this pump has a magnetic clutch. That won't work with standard magnets above 170F. Even 172F, which is what I target in the hlt, apparently demagnetizes the magnets.

Now I'm left with a puzzle. I bought this pump because the nice folks at MoreBeer said it could handle boiling wort and they've never sent me wrong before. Plus, I've seen lots of posting on their forum, including one from Jamil 2 years ago, saying they've had success with this pump. But I think it's physically impossible to have success with this pump, unless I'm doing it wrong.

Is 170F too hot to sparge at? Did older versions of this pump have special magnets that can handle the higher temp? Does shaving cream actually soften your beard? Will this posting ever end? Guess I'm still writing.

[Dr Scott]

I use two of these pumps and routinely pump 212F liquid through them both. So I don't think it is a temp thing unless I'm reading your post incorrectly. These pumps are not self priming. So if you get some air in the pump housing it will cavitate.

Sometimes you need to get some flow started (gravity feed) before the pump can push. Head height can be an issue too, slowing the output. Sometimes flicking the pump switch quickly on and off 5-6 times will get things started.

[tnlandsailor]

Rare earth magnets may demagnetize at 170, but ceramic magnets do not. Your pump is fine. I think your problem is priming.

Magnetic pumps need two things to work correctly:

1) They need to sit below the source liquid. In other words, they don't "pull" liquids uphill very well. They need positive head to the inlet of the pump housing connection.

2) They need to be primed. That means the housing needs to be completely full of liquid before it will actually pump anything. If there is any air in the housing, the pump will make a lot of noise and not really pump out any liquid. All the air needs to be purged before it will work.

To prime the pump, make sure the pump is off. Open the inlet valve and the outlet valve, then take your outlet hose and direct it to a low point below the pump so that liquid will flow through the pump by gravity. Once all the air has been purged from the pump housing (5 - 10 seconds), close the outlet valve (leave the inlet valve open). Now take your outlet hose and direct it to the intended destination and turn the pump on. Now open the outlet valve and the pump should begin pumping. If it doesn't repeat the process.

Only use the outlet valve to meter your flow, do not use the inlet valve or else the pump may begin to cavitate (heard as a loud rattling noise) which can damage the pump. The outlet valve can be manipulated at will with no effect on the pump.

[peterc]

Hmmm, I don't think it's priming but I'll pay some extra attention to that. The pump seems to work fine for several minutes and then just stop working. It also seems to "just stop" corresponding to my increasing the temperature.

It occurred to me that I can do an experiment with the magnetic wheel that's inside this thing to test my temperature theory. I'll just load up the magnet with paper clips and suspend it in water while I heat the water up. If a large number of clips fall off at 170F I'll be pretty convinced it's the temp and that some of these pumps have different magnets than others. If they don't then I'll know I'm a dumbass and need to try harder.

Thanks for the tips. I'll post a follow up tomorrow.

[peterc]

I have the facts and I'm voting dumb ass. Thanks for helping to set me straight on this. I did the paper clip test and it pretty clearly isn't demagnetizing. I thought I was priming the pump but I honestly wasn't being very careful about it.

It's good to know it's me and not the equipment. I'm easier and cheaper to fix.

[JP]

It could also be that your lines are leaking air at teh screw clamps. Try tightening them up a bit and see how that goes.

[jamilz]

I think JP has the answer. An air leak is the only reason I can think that 170F liquid would stop flowing after a while. The pumps are pretty much bulletproof. I have never had any real trouble with them.

[peterc]

I took a look at the connection from the hot tank to the pump inlet and found an air leak there. I put some fresh plumber's tape on the threaded connection there and tightened the crap out of the hose clamps and that fixed the problem.

I was able to sit back and watch my sparge for 60 minutes instead of having to dick around with it for an hour. Thanks for the help guys!