Herms-loop makes system cavitate

[Smellyglove]

Sorry I keep beating this horse, but it isn't dead until the sound of air is gone..

I've tried restricting the output, but that didn't seem to help much. Although it was a logical thing to do.

I just discovered something new.

I tilted the mt just to drain it, it's a 10g boilermaker. And as I tilted it huge amounts of air escaped from under the FB. I have NO idea what that amount of air was doing down there. This is a mystery to me. So I'm guessing I'm sucking that air into my pump. Now the question is if that air builds up over time, and if it does, why does it happen.

Idk if this has anything to say, but when I open up the priming valve, which is located on the pump exit, it immediately sucks tonnes of air.

Could it be that the FB is to tight for how I'm running the system? There's way more restriction after the pump (herms and sparge arm) than before the pump.

Thanks for your patience guys. Everything helps.

Btw, I'm 100% sure its not a leak in threads, I've swapped everything, but I haven't run the system without the FB.

Edit: even clogged the sight glass, no difference. The water which i start out with is very cold. Its winter here in Norway.

 

[Smellyglove]

What is the inside diameter of the herms coil? How long is it?

I know the OD. Which is 1/2" and its SS. about 6-7 feet long. I'm restricting it when I recirc, or else I'm getting a brick grainbed.

 

[pablosbrewing]

Sorry I keep beating this horse, but it isn't dead until the sound of air is gone..

I've tried restricting the output, but that didn't seem to help much. Although it was a logical thing to do.

I just discovered something new.

I tilted the mt just to drain it, it's a 10g boilermaker. And as I tilted it huge amounts of air escaped from under the FB. I have NO idea what that amount of air was doing down there. This is a mystery to me. So I'm guessing I'm sucking that air into my pump. Now the question is if that air builds up over time, and if it does, why does it happen.

Idk if this has anything to say, but when I open up the priming valve, which is located on the pump exit, it immediately sucks tonnes of air.

Could it be that the FB is to tight for how I'm running the system? There's way more restriction after the pump (herms and sparge arm) than before the pump.

Thanks for your patience guys. Everything helps.

Btw, I'm 100% sure its not a leak in threads, I've swapped everything, but I haven't run the system without the FB.

Edit: even clogged the sight glass, no difference. The water which i start out with is very cold. Its winter here in Norway.

Back to the photo - if I understand correctly that ball valve on the output of the pump is your priming valve. If so then you are missing a second ball valve on the output of the pump - that is the only place you can throttle the flow in this setup without cavitation/compacting the mash/pulling air.

 

[Smellyglove]

I have a ball valve on the sparge arm, after pump and herms. Its on the far end on the loop. Do Ineed one just after the pump?

Edit: added a valve just after the priming valve, restricted A LOT, same thing happens but slower than before.

 

[Smellyglove]

Current setup

View attachment 1421452563629.jpg

 

[Smellyglove]

Cavitation and air bound will both cause your pump to run crappy.

Cavitation is caused by restricted flow on the low pressure side which causes a large pressure drop and the liquid phase changes to a gas. When it passes through the pump to the high pressure side, the gas bubble phase changes back causing the bubble to implode. The impeller is usually the preferred place for it to implode and will eventually destroy the impeller.

Air bound means you have air in the pump. Air bound will cause the pump to run very hot.

I'd disconnect the HEX coil and run MT -> pump -> MT or to a bucket. You should still have the same problem. If you do, it proves the problem is on the suction side and narrows it down for you.

I just started to re-read the thread and I think I missed this post. Great reply, wish I saw it sooner

 

[pablosbrewing]

I have a ball valve on the sparge arm, after pump and herms. Its on the far end on the loop. Do Ineed one just after the pump?

I don't think you can safely shut that valve off without some risk of bursting the hose, and you will be shutting it way down. Move that valve to the pump (right after the tee where your bleeder is).

You can only pump wort as fast as it will gravity drain through the mash without becoming stuck, or pulling air. Some folks have crushed false bottoms with these pumps by running the flow wide open.

 

[Smellyglove]

I don't think you can safely shut that valve off without some risk of bursting the hose, and you will be shutting it way down. Move that valve to the pump (right after the tee where your bleeder is).

You can only pump wort as fast as it will gravity drain through the mash without becoming stuck, or pulling air. Some folks have crushed false bottoms with these pumps.

Check my edit just before my last pic.

 

[Smellyglove]

I don't think you can safely shut that valve off without some risk of bursting the hose, and you will be shutting it way down. Move that valve to the pump (right after the tee where your bleeder is).

You can only pump wort as fast as it will gravity drain through the mash without becoming stuck, or pulling air. Some folks have crushed false bottoms with these pumps.

Check my edit just before my last pic.

 

[Smellyglove]

Even if i close the new restricting valve on the output of the pump it happens..

 

[brick_haus]

I work with centrifigual pumps all day, every day and have for over 25 years. The cause of the discharged air can only be attributed to a couple things.
1. You have an air leak in the suction side of your system. Hoses, fittings etc.
2. You are pulling air into the suction by having insufficient liquid above the suction in your tank MLT (slurping?)
3. If the liquid is hot, it will convert to gas(steam) at a lower temperature than "normal" if the pressure is reduced enough. The required pressure to keep the gas entrained in solution is reduced as temperature increases.
4. Turbulance is a pressure reducing mechanism. Get rid of that Ell attached to the pump suction and run hose to straight barb.

Check your hoses for pin holes.
Pressure test your suction plumbing.
Make sure that you have sufficient liquid above the suction in your MLT (the air under the false bottom is curious)

Its a simple problem to fix. Proper troubleshooting is the key.

 

[Smellyglove]

What is the inside diameter of the herms coil? How long is it?

See answer a few posts up.

 

[trimixdiver1]

Even if i close the new restricting valve on the output of the pump it happens..

What? You shut the pump discharge valve and you still have flow with air in it? At this point you may want to tear everything down, redesign so there is no 90's, valves etc, within 10 plus inches of the suction, may also want to use a larger suction hose. Re tape all fittings, and move on from that point.

 

[grathan]

The latest pic you posted still has the tee and no valve.

 

[Smellyglove]

The latest pic you posted still has the tee and no valve.

What? Where?

 

[Smellyglove]

Today

View attachment 1421687530088.jpg

 

[Smellyglove]

Restricting valve on the output. Sucks air.

I've swapped every piece in the setup. I know the fix is simple but still...

 

[Smellyglove]

Also tried running a long hose so that there is no 90 on the input.

 

[Smellyglove]

For every tip on this thread I get, amd rebiild the setup... Ive tried everything.

 

[Smellyglove]

It works when set temp is reached. Thats it. Works with cold water, and set temp water. Everything between that doesnt work.

 

[grathan]

What? Where?

On the pump output. You have a tee. Perhaps this is common, but I see an opportunity for an air bubble to cavitate back into the pump if the output flow is limited. This would not explain the massive air pocket that gets created under the false bottom though (though you've only encountered this once and have not determined if the pump was cause).


I would try removing the tee and the extra priming drain hose and just have a ball valve there connected to only the main output hose. To prime, don't turn the pump on until there is at least 5 inches showing above the pump. close the output valve and turn the pump on. slowly open the output valve so that you get a flow, but not too much flow. Make sure the supply side can keep up with the output side. Look for air bubbles in the output hose/tank (there should be none).

 

[Smellyglove]

Another brewday another...

Does it tell anybody something that less water in mt equals more air in pump?

 

[mrwizard0]

Have you tried rotating the pump head 90 degrees so that the inlet is at the bottom and the output pointing up?

 

[Smellyglove]

Yes. Trust me, I've tried more or less everything.

I'm brewing right now and as I'm heating up to strike temp I removed the FB. Way less problems so far. Way less as in it takes way longer before I can hear the air, and the air-sound rises gradually instead of a close to sudden inlet of air as with the FB. But now there is a different sound. Ek ek ekek ek, or how to describe it... pop pop pop

I'm pretty sure it has something to do with the boilermaker. And low OG beers makes it more extreme.

 

[Smellyglove]

Partially solved.

I went all in an let it bleed until the I had 1/3 of the water left. Shook the BM like a person with a mental illness and its almost all gone. I guess the BM FB traps a whole lot more air than I could imagine.

 

[trimixdiver1]

Partially solved.

I went all in an let it bleed until the I had 1/3 of the water left. Shook the BM like a person with a mental illness and its almost all gone. I guess the BM FB traps a whole lot more air than I could imagine.

The Blichmann FB is very tight compared to others. Good work.

 

[RBGilbert2]

I have a similar HERMS system but w/o the Blichmann FB. I fill my mash tun from the HLT by pumping in through the kettle valve, i.e., from the bottom. Would that limit air below the FB for you?

 

[Smellyglove]

I have no idea. Maybe the bubbles would just be shuffled around under the FB, I don't know. It seems that I actualle have to lift the FB at one end and shake the kettle to effectively get rid of air.

My new technique is now placing the FB after filling water, diptube pointing up. Then reprime and shake the kettle after the herms has heated it to about +40c from initial temperature.

 

[cbhxh]

What is the inside diameter of the herms coil? How long is it?

 

[Smellyglove]

Troll?