Air in line during Recirculation

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

dr_finklestein

Well-Known Member
Joined
Aug 4, 2008
Messages
220
Reaction score
5
Location
Colorado Springs, CO
I have been getting air in my line, right at the valve on my mash tun, when I recirculate. I have checked the clamps on the hoses to my camlocks, took apart my ball valve, and replaced my mash screen, but still get air in the hose. It only happens once the grain bed gets settled. Any ideas where this is coming from? Is it the camlocks?
 
my mash does the same thing, over time mine will go away and some beers i dont see it at all. its not a big deal, slow down your recirculation some and see if that helps at all. Iv been running mine for about a year now and never notice any flavoring it produces
 
Quick question, how do you mash in? I personally, mash in from the bottom of my kettle and this helps remove any air in the line. That being said, you can run the risk of moving your false bottom if your not careful. Mine is wedged pretty tight and won't be moving unless I pull it out.

Hope this helps..
 
my mash does the same thing, over time mine will go away and some beers i dont see it at all. its not a big deal, slow down your recirculation some and see if that helps at all. Iv been running mine for about a year now and never notice any flavoring it produces

Mine doesn't go away, it actually cavitates the pump and all flow stops.
 
Quick question, how do you mash in? I personally, mash in from the bottom of my kettle and this helps remove any air in the line. That being said, you can run the risk of moving your false bottom if your not careful. Mine is wedged pretty tight and won't be moving unless I pull it out.

Hope this helps..

I put the water in the tun first and then add grain. I think I am going to purchase a false bottom from Jaybird and see if this helps. Any other advise>
 
dr_finklestein said:
I put the water in the tun first and then add grain. I think I am going to purchase a false bottom from Jaybird and see if this helps. Any other advise>

I just thought of one other thing. Can you post how you have the pump mounted?

The direction of the pumps should look similar to this.

ForumRunner_20121030_221730.jpg

If they are opposite, you most likely will have air in the lines all the time.
 
Your pump is pulling liquid faster than it will drain through the bed by gravity alone.
The typical tube style mash screen does not provide enough surface area
for a fast flow rate even with a thin mash.
From other threads, this seems to be less of a problem with a false bottom.
Once the grain bed settles, flow rate decreases significantly.

I suppose the pump could also be compacting the grain bed
by creating lower pressure at the bottom of the bed.
Which would make the situation worse of course.

We seal our tubing, connections, pump housing to keep liquid in.
It might be too much to expect them to keep air out under increasing negative pressure.

The solution is to slow down the recirculation rate to the rate of normal gravity drain.
But I don't know how you would do that without a pressure meter before the pump.
I gravity drain from my mlt to the bk and then drain to the pump which recircs back to the mlt.
I have to slow down my pump to match the mlt drain or the pump runs dry.
I never get pump cavitation during mash recirculation.

The brutus 10 folks don't seem to have this problem.
I suspect a false bottom on a 15 gal pot with a thin mash gives them
a good enough drain rate that the pump can run fast.

I am interested in how the false bottom works for you.
I may give that a try in my round cooler to increase my mlt drain rate.

(most of the above is opinion based on experience on my system, ymmv)
 
If you don't have one, get a sight glass. You will see the influence of pressure on the bed when you recirculate. It's very helpful and you'll know when you need to slow down.
 
Your pump is pulling liquid faster than it will drain through the bed by gravity alone.
The typical tube style mash screen does not provide enough surface area
for a fast flow rate even with a thin mash.
From other threads, this seems to be less of a problem with a false bottom.
Once the grain bed settles, flow rate decreases significantly.

I suppose the pump could also be compacting the grain bed
by creating lower pressure at the bottom of the bed.
Which would make the situation worse of course.

We seal our tubing, connections, pump housing to keep liquid in.
It might be too much to expect them to keep air out under increasing negative pressure.

The solution is to slow down the recirculation rate to the rate of normal gravity drain.
But I don't know how you would do that without a pressure meter before the pump.
I gravity drain from my mlt to the bk and then drain to the pump which recircs back to the mlt.
I have to slow down my pump to match the mlt drain or the pump runs dry.
I never get pump cavitation during mash recirculation.

The brutus 10 folks don't seem to have this problem.
I suspect a false bottom on a 15 gal pot with a thin mash gives them
a good enough drain rate that the pump can run fast.

I am interested in how the false bottom works for you.
I may give that a try in my round cooler to increase my mlt drain rate.

(most of the above is opinion based on experience on my system, ymmv)

I try to set my recirc. very slow to match the screen (I don't throw it wide open). My grain bed is very compact so I suspect that the problem is what you described above. I should get the FB this week and might be able to try it out it out on a batch this weekend.
 
I just thought of one other thing. Can you post how you have the pump mounted?

The direction of the pumps should look similar to this.


If they are opposite, you most likely will have air in the lines all the time.

My pump is mobile so it sits side to side. I thought about putting it vertical, but with my current set-up I don't think it's possible.
 
As long as the outlet is higher than the inlet it's typically ok to be mounted in either horizontal or vertical direction. I called Walter @ March Pumps and he confirmed this. Although I opted for vertical mounting because it's easier on the head with all the additional plumbing attached.

Even with this orientation, I still have air in the line until my flow rates equalize and then everything is fine from then on. And I prime the pump as well so that has nothing to do with it. It's purely a flow issue.
 
If you don't have one, get a sight glass. You will see the influence of pressure on the bed when you recirculate. It's very helpful and you'll know when you need to slow down.

+1 to this. I have found out that a lot of my air seepage was through the sight glass if I recirculate at full volume! My sight glass is set just above the false bottom, so most of the grain bed is above it. At full volume recirculation the liquid level in the glass drops to zero and air gets sucked in. If I want to recirculate at high volume I put a plug in the top of the sight glass first.
 
Hmm... that's interesting. I think you want to be below the grain bed though. If you're above the bottom then your sight glass can get clogged just from simple grain build-up. When it's below and you see your liquid level dropping it means your grain bed is so compacted it's not letting liquid filter through - hence stuck mash. Usually it means you're trying to recirculate too fast and you're pulling liquid faster than you can return it which has a vacuum like effect on the grain bed. Once you slow the flow a bit and equalize the exit and return flow then it relaxes and all is well.

One key is when you mash-in don't try to go full-bore. The recirculation should be pretty slow at this point until the bed has a chance to set. And then you can slowly increase the flow and often times you'll get close to or at full flow. But that doesn't mean you shouldn't keep an eye on it. I've certainly had plenty of occasions where 60 minutes into a mash it starts to stick.
 
I have been getting air in my line, right at the valve on my mash tun, when I recirculate. I have checked the clamps on the hoses to my camlocks, took apart my ball valve, and replaced my mash screen, but still get air in the hose. It only happens once the grain bed gets settled. Any ideas where this is coming from? Is it the camlocks?

sounds like a leak somewhere. a steady stream of air is not caviation from the pump. if there is a bit of weight pulling the camlock connection to one side, that could create a small opening near the seal and let air in. an easy test is just pushing the fittings together as hard as you can and seeing if the bubbles stop.

if you see the bubbles in the hose between the mash tun and the pump, i would suspect the camlock on the mash tun. if you see the stream of bubbles only coming out of the pump, i would suspect the camlock on the pump input.
 
I did my first batch yesterday with the new false bottom. I did a Wit which was basically 50% Wheat 50% Pils. I added rice hulls (as I always do with a wheat ale). I started to recirc. and the pump ran for about 15 minutes before air started to form again. Although not great but this was much better than last time. I stopped every thing, restirred the mash and started to recirc again but this time I really slowed down the flow. It worked perfectly. I will try it again on a Bock on tomorrow.
 
Back
Top