Chugger Pump - HLT not draining completely with pump

So I just finished my new brew stand build and am having an issue with the pump. I built a two tier system. HLT is on a burner at the bottom, MT above the HLT, and then BK off to the side on its own tier. My HLT is a 7.75 gallon half keg. When I welded the bung for my ball valve, I accidentally put it just below half way up the keg. I bent a piece is SS tubing in to a dip tube to draw from the bottom of the HLT. From there it goes through a ball valve and some more SS tubing to my pump which is located below the bottom of the HLT. The pump is a Chugger SS inline. The issue I am having is that the pump will only drain the HLT to about an inch below where I welded the .5" NPT coupling as a bung. Why is this? Since I have a dip tube, shouldn't that draw a natural siphon to my pump which is lower than the lowest point of the dip tube? From there the pump should maintain that siphon and then pressure pump up to my MT? Does the Chugger pump I bought not actually draw liquid from the input side? If I raised the HLT would that give more of a siphon effect? Or am I completely over thinking this?

How is the pickup tube connected inside? I would guess you have air leaking into the connection on your pickup tube.

5000 psi SS compression fitting. Comp X NPT then threaded in to the coupling/bung. I tightened the heck out of it. I may try some dope as opposed to tape. Once I get home from work I will post some pictures.

View attachment ImageUploadedByHome Brew1484952949.895019.jpgView attachment ImageUploadedByHome Brew1484952964.756480.jpg

Here are some pictures. Ignore the poly tubing.

It's one of two things. Both cause the same effect.

1. Air leak somewhere in the line. Most likely something that is covered by water at some point. It pumps fine until the water level exposes this fitting leak to air. More Teflon tape and re-tighten all fittings.

What I think it is.

2. The pump is pulling to hard and causing cavitation around the dip tube opening. Put some water in the HLT and turn on the pump. Watch the dip tube see if the surface of the water is being pulled down around the dip tube letting air in.

The majority of setups with pumps setups have a ball valve right on the output of the pump. This is used as a throttle control for the pump. Closing down the output will keep the pump head from filling with air and causing the cavitation. I see you don't have one but you could try closing the output ball valve on the HLT a little and see if that will help. I don't think it will because the pump will still be running full throttle and closing the that valve will just starve the pump. Causing the same problem.

I'd put a ball valve on the output of the pump and as the kettle drains slow the flow to prevent cavitation.

Oh I get what you are saying. Issue is though that it pumps to a point and then stops. So it wouldn't be a back pressure issue on the pump. I did go back and found a small pin hole on the pump head casting. Put a spot weld on it. Maybe that was the problem... we will see...

PurpleJeepXJ said:

Oh I get what you are saying. Issue is though that it pumps to a point and then stops. So it wouldn't be a back pressure issue on the pump. I did go back and found a small pin hole on the pump head casting. Put a spot weld on it. Maybe that was the problem... we will see...

Click to expand...

I don't think the pump head hole is the problem. It pumps fine with the HLT full. With a pump head leak you would have the same problem no matter how much water is in the HLT. You only have pump problems when the water level get low. I still think it's the pump running wide open issue. At low levels the water is dipping down below the dip tube and allowing air in the line starving the pump.

Does it pulse when you start to get low on water? Siphoning action breaks, the pump cavitates, water settles in HLT, pump tries to reprime, sputters as the vacuum breaks the surface tension of the water, right back to pump cavitates.