Herms-loop makes system cavitate

[Smellyglove]

Can a mod change the topic of this thread to "Blichmann false bottom, pump sucking air" ?

I just accepted how it was, but after getting pretty fed up with this **** last time I brewed I just came to the simple conclusion that it might work if I fill up the mash-tun through the diptube... And it works!

I've tried some testing with plain water.. Fill up HLT, let gravity prime the March, then connect the output to the march to the spigot on the mash tun, so the water slowly fills from the bottom pushing trapped air under the blichmann false bottom out. Press the FB quickly some times to press out any air that might be left..It works. No air whatsoever.

 

[Assoc]

Make sure you have enough space between the dip tube and the bottom of your kettle.

 

[Beernik]

I'll reiterate my original question to the OP: are you sure it's cavitation? Does it sound like there is gravel in your pump. If it doesn't, its likely that it's air and not cavitation.

Cavitation causes are on the suction side of the pump. It's either not enough net suction head or a flow restriction on the suction side. When either of those happen, the suction can cause a phase change from liquid to vapor and make a bubble. As soon as that bubble hits the pressure side, it implodes, usually on the impeller or pump housing and causes that gravely-crunching-hammering sound.

If you are seeing bubbles in the flow on the pressure side, it's not cavitation.

Also, if there is a sound and it's more of a high pitched whine, it's likely air bound instead of cavitation.

 

[Smellyglove]

No its' air.

But it was another false alarm that it works now. Whenever the water temp rises it starts pulling air again. So I'll just start heating my strike water in the HLT to get rid of the air, and then pump it over to the MT.

 

[Smellyglove]

This time I'm positive it's been solved!

Heat strikewater in HLT to get rid of all gasses in the water, fill MT from bottom after a good prime, no air, tried three times now.

 

[Beernik]

Sorry @smellyglove. I meant that I was asking @chjgj the same question.

 

[Smellyglove]

Aha!

 

[Smellyglove]

I have spent almost nine hours trying to figure out why I get cavitation in my system. I've narrowed it down to the herms-loop, but that's it.

You seem like being in my situation until I figured it out. What's you setup?

Haha, bogus post. That was my first post in my thread. A bot?

 

[Smellyglove]

Just the tap of it is longer than your dick, that's for sure. How do I ignore people on this forum? MF bots.

 

[Smellyglove]

I'm back and im just as frustraded as before.

7.5G boilermaker this time. It happens whenever the herms fires. Any way of resolving this besides of heating up the mash water to let the air get out of solution before I dough in?

 

[jddevinn]

I'm back and im just as frustraded as before.

7.5G boilermaker this time. It happens whenever the herms fires. Any way of resolving this besides of heating up the mash water to let the air get out of solution before I dough in?

What do you mean by "whenever the HERMS fires"? Do you mean whenever the heating element is actually active?

Is it possible that you have the HERS coil too close to the element and are heating the liquid in the coil directly too hot? You are recirculating the HLT water?

Do you still have the small ID tubing? If so the water coming out of the HERMS coil has an expanded flow area as soon as it exits, meaning that it's velocity and pressure decrease. Are you somehow flashing in here? What's the inside of the mash look like?

Can we get a picture of the current system? Where are the temperature transducers located? What is your set point for the HLT?

 

[Smellyglove]

I wrecked my pump so I stowed it all away waiting for a new SS head before I took any pics. But, I tried it as straight as possible. Boiler maker - pump - boiler maker. Hose straight on barbs. The air just magically appears. I can see bubbles coming out of the barb from the BM. It's amazing! Where does that air come from? Even with the diptube above the FB. Even with the valve on the directly on the output on the pump almost closed, everything from full open to almost closed = air. Where does it come from? It seems like it just magically just appears somewhere inside the BM.

 

[jddevinn]

If there is no air leakage you are flashing the water/beer into steam somehow through a pressure drop.

 

[Smellyglove]

If there is no air leakage you are flashing the water/beer into steam somehow through a pressure drop.

I see air bubbles coming from the Blichmann-kettle. I use 10mm ID hoses, throttling the output valve on the pump way back just makes it happen slower. I don't get it. Even without the FB.

 

[jddevinn]

Into the kettle?? That wouldn't be steam it has to be water. We need some pictures and maybe video. Where are you at? Maybe you'll get lucky and be near someone that'll come take a look with new eyes.

 

[Smellyglove]

Into the kettle?? That wouldn't be steam it has to be water. We need some pictures and maybe video. Where are you at? Maybe you'll get lucky and be near someone that'll come take a look with new eyes.

From the kettle, or.. mash tun. Not into it.

I had some minutes to spare today and found two other barbs. The ones I've been using haven't been 1/2" ID. So I swapped them with one fat ass (20mm OD) and one which seems like it's 1/2" ID. The result was that I could run the pump with the restriction valve half open before I could hear any air. Which is better than it has ever been with this setup.

I'll try uploading some pics when I have the time.

 

[jddevinn]

I guess im sucking air. Does this point have to be before the pump, or can it be after also?

Your images are not showing up.

Sucking air has to be before the pump. After the pump the line is pressurized and a leak would spray water OUT not let air leak IN.

 

[The_Bishop]

He was a copy/paste spammer.

 

[jddevinn]

He was a copy/paste spammer.

I had a suspicion when I saw the link address for the "photos"

 

[Smellyglove]

I started from scratch to day. No QDs, just hose barbs. That worked so in with the QDs. That worked too. So in with the HERMS-loop, that worked too, for maybe an hour and then I shut it off. So lets try with the heating element ON.... Does NOT work, a while after the HERMS starts I can hear air in the pump head.

Test-scenario today:

 

[jddevinn]

It looks like the HERMS coil and the heat exchanger are in a very small HLT. How and where are you monitoring temperatures? Are you overheating the water in the coil?