Help Trouble shooting Chugger Pump

[sancycling]

Hi All. I would like to get some ideas on why my brand new Chugger pump is not working. I've read several posts and ran tests but still having issues.

Issue: Pump won't pump liquid. It worked well when recirculating the mash for 90minutes. Would not work with boiling water. When started it pumps for a couple seconds and then stops.

- Motor runs well. When disassembled, the magnet spins perfectly
- Cheched de alignment and there is no rub from the magnet and the pump head
- No contaminants or debrie inside pump head
- Impeller spins freely when disassembled and there is no play. Washers are in perfect shape.
- Using a 1in braided silicone hose for input, 2.5ft long and 1/2 in braided silicone hose for output, 5ft long.
- Pump was primed correctly. It is connected to the bottom valve of a conical, sits 1 ft below water/wort (10-15 gallons). I moved the pump around to make sure there were no air bubbles.


I believe it could be two things.

1) The pump is cavitating and somehow starving so the impeller spins "dry". But the input is completely free, there is no restriction, the valve is completely open (1in valve) and it has all the pressure from 10gallons. Could it be that I don't have enough restriction in the output?

2) Some how the magnet is not moving the impeller. But when reassembling the pump head, the magnet pulls with quite some force.

Any ideas? What else should I look into?

Thanks

 

[GilaMinumBeer]

Have you checked to see if the input hose is collapsing? Do you have anything restricting flow to the input hose (hop blocker, braided filter, etc...)

It is possible that if the pump is pushing out faster than is being fed in, the soft silicone input hose could be collapsing and breaking the prime on the pump.

 

[sancycling]

The hose is not collapsing. It is supposedly a kink free braided hose 1 in. But I did check, and the hose was fine.
There are no restrictions. The 1in ball valve is completely open.

 

[CA_Mouse]

The hose is not collapsing. It is supposedly a kink free braided hose 1 in. But I did check, and the hose was fine.
There are no restrictions. The 1in ball valve is completely open.

Where inline is the ball valve? It should be after the pump. Try running it with the valve only part way open and see if it maintains the desired pressure.

I added 2 ball valves to the output side of mine when I built a waterproof container. The first ball valve is used to bleed the air from the line and the second one controls the flow either for mash recirculation, wort recirculation or run off to the fermenter.

 

[brick_haus]

This Happens to me sometimes. I have to disconnect the output line to allow the fluid to get into the pump. It somehow gets vapor locked and wont allow the fluid to freely flow.

Another possibility is that you are getting a vapor lock from pulling a vacuum on the already boiling hot liquid.

 

[sancycling]

CA_Mouse. I have a valve in the input as that is necessary to close the conical when I disconnect the pump. But it is completely open when I run the pump. It is not restricting flow at all.
But I think you might be giving some ideas. When I successfully recirculated the mash, I had a valve in the output to reduce/control the flow, But when I tried to transfer the boiling wort I was not using any valve in the out hose. Could this change be the issue?

 

[Gameface]

You can't pump boiling liquid, it is releasing water vapor that will cause cavitation.

 

[doug293cz]

This Happens to me sometimes. I have to disconnect the output line to allow the fluid to get into the pump. It somehow gets vapor locked and wont allow the fluid to freely flow.

Another possibility is that you are getting a vapor lock from pulling a vacuum on the already boiling hot liquid.

Bingo! With the water at, or close to, boil temp, it takes very little suction (pressure drop) to create a lot of steam in the pump, since water boils at lower temps at lower pressures. Gas rather than liquid in the pump kills the suction, and causes you to lose prime.

Brew on

 

[CA_Mouse]

CA_Mouse. I have a valve in the input as that is necessary to close the conical when I disconnect the pump. But it is completely open when I run the pump. It is not restricting flow at all.
But I think you might be giving some ideas. When I successfully recirculated the mash, I had a valve in the output to reduce/control the flow, But when I tried to transfer the boiling wort I was not using any valve in the out hose. Could this change be the issue?

I believe it could. By having the valve on the output side, you are able to keep liquid in the pump head. Cavitation only takes a small amount of air to stop the flow. As someone else stated, a boiling liquid contains more vapor than room temp liquid. By slowing the flow on the exit side of the pump head, you allowing the vapor to dispersed before it get to the head.

 

[day_trippr]

Slowing the flow raises the effective system pressure at the kettle valve, which helps keep the boiling point of the fluid therein closer to that of the kettle contents. It's the pressure drop at higher flow rates that causes the flash boil effect which in turn cavitates the pump head.

With a 3-vessel/2-pump herms rig I have to deal with this all the time.
The pumps announce when I forget to dial a valve down...

Cheers!

 

[sancycling]

Finally had a chance to run some tests.
The problem was that I did not have a valve in the output. Therefore the pump was cavitating and not able to push liquid.

I attached a valve in the out hose and started the pump with the valve closed, then slowly opened the valve. If I open it completely, the problem returns. But restricting the out just a little bit makes the pump work beautifully even with boiling water.

Thanks for everyones help. Problem solved... or user error found.

 

[day_trippr]

[...]Thanks for everyones help. Problem solved... or user error found.

Excellent.

As for "user error", I bet every single person who got started recirculating the BK has run into this, and some are likely still fighting it because they don't understand the physics...

Cheers!