Fermenter Headspace

[markarena]

Hi everyone! Long time lurker first time poster.

I've recently done my first all grain batch (it's an American Pale Ale), which yielded about 7-8L of wort in the fermenter, as that's the limit of my aluminium pail for the boil. I put this into a glass fermenter that you would normally put 23L or so into.

My question is: is it a good thing to have this much headspace in the fermenter? I have noticed that air is being drawn into it through the airlock, which can't be good.

 

[lagers44]

Hi Mark

Welcome aboard. I wouldn't worry about the headspace as some English breweries use open vat fermenters. I would be concerned about the air being sucked in but that'll stop as the temp differential equallises. Just make sure the water in the airlock is sterile but if you pitched good yeast it should be OK. I've not had problems in years of brewing.

Good luck...keep brewing

Lagers

 

[rich_lamb]

The headspace is not an issue.

Air is being drawn in? - I assume this means the airlock is on while the wort cools down?
Generally, you cool your wort before you pitch and then put the airlock on, and it's pretty much exposed to air during that time so if you're letting it cool with the airlock on it can only be better. Maybe overkill though.

You may also quickly come to the conclusion all that work for 7-8L means you need a bigger kettle... new burner... more mashing gear... etc. etc etc

 

[Swinging Beef]

8 litres?
wierd.. I thought every was bigger in WA.

 

[Ronin]

Hi everyone! Long time lurker first time poster.

I've recently done my first all grain batch (it's an American Pale Ale), which yielded about 7-8L of wort in the fermenter, as that's the limit of my aluminium pail for the boil. I put this into a glass fermenter that you would normally put 23L or so into.

My question is: is it a good thing to have this much headspace in the fermenter? I have noticed that air is being drawn into it through the airlock, which can't be good.

I brewed 10L batches for a few years after I first went all grain for several reasons, kettle space limitations amongst them. I always fermented in my standard 23L fermenter and never had any issues at all. Once the fermentation starts it's all CO2 in the headspace anyway.

 

[markarena]

Thanks everyone for your comments.

I am restricted by my boil kettle right now, I could go a bit more if I did a split boil, but the simpler I can make my all grain experience right now, the better. My extract brews go to about 20L.

This batch was cooled down before it went into the fermenter. For the last week it has periodically drawn in air. I suspect this is because its in an area that the fermenter is exposed to day/night temperature variation. My temperature control is lousy right now, until I get my fridges in the shed, which is this week.

I was interested in what situations air would be drawn into the fermenter, and I thought the headspace might be an issue, but it could be just the position of the fermenter.

 

[Ronin]

Thanks everyone for your comments.

I am restricted by my boil kettle right now, I could go a bit more if I did a split boil, but the simpler I can make my all grain experience right now, the better. My extract brews go to about 20L.

This batch was cooled down before it went into the fermenter. For the last week it has periodically drawn in air. I suspect this is because its in an area that the fermenter is exposed to day/night temperature variation. My temperature control is lousy right now, until I get my fridges in the shed, which is this week.

I was interested in what situations air would be drawn into the fermenter, and I thought the headspace might be an issue, but it could be just the position of the fermenter.

As in the wort's been in the fermenter without pitching any yeast? Once fermentation has started you should have positive pressure and not much should be getting drawn in, even with temperature variation.

If fermentation has finished, I use to rack my 10L batches into 10L jerry cans you can get at bunning/mitre 10 which can be sealed airtight.

 

[markarena]

No, the yeast is in there. In fact it's overdue to be bottled by a few days.

 

[markarena]

8 litres?
wierd.. I thought every was bigger in WA.

I am talking WA litres of course. Good pickup!

 

[chris.taylor.98]

When I used to use airlocks, I did have occasions where the air would drawn in (backwards) through the lock.

This was usually when doing beers with high gravity OG during the lag phase (right at the start).

I am suspecting in this case the yeast does not have enough oxygen and is trying to suck in more oxygen before it enters the anaerobic state.

Try aerating the wort more thoroughly and/or pitching more yeast to avoid this in the future.

As others have said headspace is not really an issue, in fact not enough headspace is more troublesome prospect.

Other causes for the airlock to flow backwards are sudden changes in ambient temp, which can cause pressure differentials between the beer and its surroundings, particularly at the end of the fermentation cycle when CO2 is no longer actively beginning produced.

 

[markarena]

Thanks Chris. My aeration method is shaking the crap out of the fermenter for a minute before I pitch yeast. I used the dried American Ale yeast, US-05 I think it is, rehydrated in pre-boiled water cooled to 35-40C. I'm thinking my laundry is acting like a hothouse in the day, although I'm pretty sure the intake of has only happened at the end of fermentation, not at the beginning. Is an infection of some kind also a cause for this kind of thing?

 

[mika]

Nope. Infection would generally cause fermentation and keep the air out. Just the temperature changes (not good) and the local changes in pressure. The bucket type airlocks are meant to be better for this.

 

[rich_lamb]

I doubt you'd have to worry about infection. At least your airlock is providing an obstructed path into the fermenter.
But your immediate problem is the temperature fluctuations which are not great for fermentation anyway. Try a low-tech solution like sticking it in some cupboard that stays at a more even temp.

On a side note: if you want to increase your volumes for a fixed kettle size you could boil slightly higher gravity beer in your kettle, and dilute it a bit into your fermenter. You need to make a few minor allowances when doing this, like hop utilisation will be a bit lower.

 

[buttersd70]

agree with B&T, you could do a concentrated boil....with the volumes you have, you wouldn't really be able to push it up all the way, but you could fairly easily increase from 7-8 L to 10-12L. The lower the required OG is, the easier it is to do this without it becoming a kerfuffle.

 

[markarena]

I did have some brews in a walk-in linen cupboard, which was great for consistency, but it's too cold at the moment (about 15C) and the fermentation was getting stuck. I have a brew belt and that's too hot, I recall seeing the temp getting to 30C odd.

I gotta get to the bottom of this air intake thing... is it likely to be related to a glass fermenter as opposed to plastic? I'm guessing glass would be more sensitive to temperature variation. What about the airlock? Mika mentioned the bucket type airlock being better, why is that?

 

[buttersd70]

I did have some brews in a walk-in linen cupboard, which was great for consistency, but it's too cold at the moment (about 15C) and the fermentation was getting stuck. I have a brew belt and that's too hot, I recall seeing the temp getting to 30C odd.

I gotta get to the bottom of this air intake thing... is it likely to be related to a glass fermenter as opposed to plastic? I'm guessing glass would be more sensitive to temperature variation. What about the airlock? Mika mentioned the bucket type airlock being better, why is that?

The air intake is related to the volume required to contain a gas relevant to changes in temperature and (in this case,atmospheric) pressure....as the temperature drops, the volume required to contain the gas drops, and as the actual amount of gas is the same, and the volume of the container can't change due to glass being hard, it will suck more air in to fill the fixed volume of the container. This can be demostrated by half filling a pet bottle with hot water, sealing it, and putting it in the fridge....the sides will suck in. crack the seal, and it sucks air into it, returning the container to it's original volume. Do the same with glass, and the glass will implode. due to the pressure imbalance, because the sides cant contract enough.

The blow off tube in a bucket counters this, because there is enough air in the tubing so that when it sucks in, it starts to suck water up....but if the tubing is long, it doesn't have enough suction for the water to get all the way through the tube and into the fermenter. The air in that length of tube is greater than the air required to replace the volume change of the air in the top of the fermenter.

 

[mika]

I meant this kinda thing. They don't seem to run backwards like the traditional 'S' style. Roy will have them in stock. They're a bugger to push into the grommet though, stem seems to be slightly larger than the S style for some reason.

 

[buttersd70]

Oh, ok. With you now, I misread what you meant. Yeah, better than the s-type, because as long as it's not over filled,the water doesn't have a direct path into the downwards tube, so any air it sucks in 'filters' through the water (or sanatiser) in it, without sucking the water in.

 

[rich_lamb]

So you've got a cool cupboard, and a heat belt. Problem solved.

Go get a cheap timer switch and use it to drive your heat belt "some of the time". With a bit of adjustment you can get the average temperature you want within a couple of degrees. It's cheap-and-dirty temp control, but people do it and it works.

Better still a thermostat controller, but it seems you are in more need of a big kettle

 

[brendo]

So you've got a cool cupboard, and a heat belt. Problem solved.

Go get a cheap timer switch and use it to drive your heat belt "some of the time". With a bit of adjustment you can get the average temperature you want within a couple of degrees. It's cheap-and-dirty temp control, but people do it and it works.

Better still a thermostat controller, but it seems you are in more need of a big kettle

I have used this method with a good deal of success.

I have also wrapped fermenters in old doonas/sleeping bags etc - helps to keep the temp a bit more stable - particularly in winter.