Need Help with Pump

[hercher]

My wife was kind enough to give me a Chugger Pump for Christmas, but I'm have troubles getting it to work. The pump itself works fine, but I think my system needs tweaking. If I have the valves wide open, it works great. It's when I try to slow down the flow that everything just stops.

My system is this:

Mash tun is a rectangular cooler with a copper manifold as a false bottom. My HLT is a converted keg. I built a PVC manifold for recirculating & sparging. So I run wort out to the pump and up to the manifold for recirculating. If I open the valve up all the way, I wind up with a stuck mash, obviously. If I restrict the flow out of the mash tun, then the pump doesn't seem to be able to get the wort back up to the sparging manifold. So I put in a valve off the out port of the pump, hoping to restrict the flow that way, but to now avail.

Surprisingly, I have the same problem during sparging.

As an fyi, I place the pump on the floor, and it probably has a 5'-6' run up to the sparging manifold. Could it be as simple as my lines being too long?

Any suggestions would be most helpful.

 

[fmr_army]

Are you flooding/filling/priming the pump completely before you turn it on? My understanding (my pump is arriving soon, I hope, so while I don't have direct experience I've been researching the heck out of techniques) is that any air in the pump chamber will really cause issues.

My understanding is that chuggers have a head lift of 18 feet, so that shouldn't be your issue.

The inlet side should be below the outlet side to keep the chamber full as well, and you should use a ball valve on the outlet side of the pump (which you're doing) to regulate flow. Maybe you're starting the flow off too fast, which may be causing a partially stuck mash/sparge? Perhaps try slowing the initial drain some?

Not much help, so I'll be interested in what the real pros here have to say.

 

[Nagorg]

is your flow control valve on the inlet or outlet side? It needs to be on the outlet side if it isn't....

Also, what is the ID size for everything from the MT to the pump and so on.. Is everything "full bore" 1/2 inch? Anything smaller than what's on the pump head will cause a flow restriction. If that restriction is going into the inlet, that could be the problem too. Are there any sharp 90 degree bends?

 

[kombat]

If I had to guess, I'd say you're getting air pockets in your feed line from the mash tun outlet to the pump, and are losing prime. If you've got air in the inlet lines, then it doesn't matter how much you restrict the valve on the outlet of the pump, you're not going to get good suction. However, I also understand that you cannot just open the valve from the mash tun wide open, as it would compress the grain bed and cause a stuck mash, as you mention you already know.

The solution is to use a grant. I recently introduced a grant into my own setup, and it fixes exactly the problem you describe.

A grant is nothing more than a small vessel (I use a 2 gallon food-grade plastic bucket) that sits below the outlet of your mash tun, and has a port (with or without a valve) at the bottom. You drain wort from your mash tun into the grant using nothing but gravity, controlling the flow with the valve on your mash tun to keep it nice and slow to avoid compressing your grain bed. As the grant fills up and covers the outlet port on the grant, you can then pump from the grant back to the mash tun however fast you want (since it's pulling from the grant rather than the mash tun, thus not creating any suction on the mash tun outlet valve). You can either constrict the flow of the pump to try and match the speeds (draining from the mash tun and pumping back to the recirculation manifold) so it can run continuously, or you can just run it wide open when the grant is getting full, then turn it off once you've drained most of it back to the mash tun.

In my setup, I have a valve on my grant outlet port. The grant sits below the mash tun, and the pump sits below them both. I connect a hose from the barb on the grant outlet valve to the pump inlet, and another hose from the pump oulet (with valve) back to the mash tun. I open the valves on both the pump outlet and grant outlet wide open as I start draining from the mash tun into the grant, so that the wort fills the line, priming my pump. Once the grant is full enough (completely covering the outlet port) and all the air bubbles in the line have burbled out into the grant, I turn on the pump and adjust the valve on the pump outlet to control the flow.

 

[jmorris62]

my experience with pumps is strictly industrial, I work on centrifugal pumps for a living. You need to ensure the pump has sufficient feed, and that means having your MLT valve all the way open. Throttling the flow on the discharge of the pump should allow you to have a sufficient flow rate without compacting your grain bed. Also as stated above, having restrictions in your fittings could also be causing an issue because it decreases your NPSHA (net positive suction head available). Just my 2 cents.

 

[dlester]

One item that hasn't been addressed is your copper manifold as your false bottom. The inlets may not be large enough to allow free flow causing the pump to struggle, and therefore, only working when a large amount of psi is applied to pull the wort out.

Just a thought,
Cheers

 

[jmorris62]

Sorry I should have specified, the restrictions in your fittings are only critical to the inlet of the pump. They need to provide the most flow to the inlet, the discharge side of the pump is less critical as the pump is designed to be able to throttle back the flow rate because it is magnet driven. Try fully open MLT valve and partially closed pump discharge valve, maybe almost all the way closed depending on how the pump reacts.

 

[hercher]

All these comments are helpful. Thanks to all. To address a couple questions that have been raised:

1. I have a valve on my MLT and another on the outlet side of the pump (about half-way between the pump outlet and the sparge manifold).
2. All hoses are 1/2" ID and fittings are barbs intended to fit same
3. There are no sharp 90 degree elbows or turns that might constrict flow.

Keep the suggestions coming.

 

[LandoLincoln]

Do this:

1) Make sure the pump and hoses are empty of wort or water and pump is off.
2) Attach hose from MLT to pump and attach outlet hose to pump but run the other end to a pitcher.
3) Open outlet valve on pump all the way.
4) Crack open the MLT valve a bit just to get the wort flowing down into the pump.
5) Once wort is flowing from the outlet of the pump, then close pump valve.
6) Verify that there's no air in the hose between the MLT and pump. If there is, then you'll have to loosen the connection between the MLT and hose to purge that air. It helps a lot if you have camlocks or some other quick disconnect for this.
7) Once the hose is free of air, then open the MLT valve all the way.
8) Put the other end of the hose wherever it needs to be (pitcher if you're vorlaufing or into the BK if you're not.)
9) Turn on the pump and verify you don't hear any bad noises. If no bad noises, then crack open the pump valve a bit to start your draining of the MLT.

What kind of pump head is on your chugger? Center inlet or inline head? This may affect things a bit.

 

[jmorris62]

If there are no flow restrictions on the inlet side of the pump, my only suggestion would be to pinch back the discharge even more. You might have a lower flow rate but how much are you looking to flow on mash recirculation anyways? The best way to counteract the problem you are describing is to add discharge resistance. It moves your point on the curve to a lower head requirement on the pump. Your problem is a common one in every industry. Without sufficient feed to the pump it will cavitate and that's bad. You counteract that by adding back pressure to the system (pinching the valve) and making the head requirement lower.

 

[hercher]

Thanks everybody for your advice. I brewed today, and drilled more (and slightly bigger) holes in my manifold, which did indeed help the wort flow a little better. Then I opened the valve from the mash tun all the way and controlled the flow with the valve I have coming off the outlet of the pump. It worked much better.

I also was a little more diligent about making sure the pump head was flooded.

Going forward, I may shorten the line from the MLT to the pump by a couple feet.

Also, I noticed the wort foamed up quite a bit on the outlet. I'm not really worried about hot side aeration because I figure the boil will get rid of all that oxygen, but I'm wondering how I can avoid that.