How hard should the boil be?

[guypettigrew]

A short while ago I bought a Buffalo boiler through the ads here. Thanks, James!

It works superbly, reaching the boil much faster than my previous boiler as it has a 2.6Kw element rather than a 2kW element. It's also larger, so there are no worries about it boiling over.

Being more powerful means it's possible to achieve a much stronger boil. If the lid is off, the wort rolls about in the boiler and is clearly boiling. If, however, I put the lid loosely on so the steam can easily escape it boils like a mad thing! Small geysers of wort thrown up, everything getting really shaken about.

Which is best, please? Is it possible to boil too hard? Or is the more powerful boil the best? There won't be any difference in temperature, at least I don't think so.

Thanks.

Guy

[barry44]

i always boil with the lid off completely.

I heard something about off flavours in covered.

[pantsmachine]

Open or partial lid boil, your choice but not closed lid.

[Rick_UK]

Wire in a temp controller so you can turn it up or down?

I had this with my old bucket boiler chez immersion element - I just kept the lid off to avoid boil overs.

Rick

[mabrungard]

The boil should produce a good 'roiling and rolling' at the surface, but it should not be leaping out of the kettle. I have a 5.5kw ultra low watt density element that I use on 20 to 25L batch sizes. If I turned my element controller to 100%, the wort would literally leap out of the kettle...the boil is that energetic. But I turn the controller down to somewhere in the 40 to 50% range and I can get a nice roil in the wort surface and I can see the hops and trub circulating. With the kettle partially covered, I boil off about 3.5 to 4 L per hour at that power setting. That is about right in my experience. An overly energetic boil will evaporate a lot more than that rate.

[RobWalker]

I'm lead to believe that hitting the boil nice and strong is a good thing, regardless of overall boil...viciousness. no science to back that up mind.

[Eric]

With a 2.4kW element in a 30 litre boiler, the stronger the boil, the better my beer. I have found it advantageous to protect the boiler from cold air and use a loose lid to control the rate at which heat escapes. In some circumstances excessive heat can cause some boiler contents to burn.

[BenB]

I'm working on the principle that unless there's scorching on the element the only downside of an overly vigarous boil is more fluid lost. But than can always be added back in afterwards. Preferably before draining the boiler.... But I do have a 3kw SCR dimmer switch with a kettle lead and socket at the ready in case I ever want to reduce my boil ferocity. With my last brew over 90 minutes and 3kw on a 19L brew I lost 17% through boil off

[Charles1968]

The point of a rolling boil is that it agitates the liquid - agitation increases the rate of the chemical processes you want to take place, including protein coagulation and alpha acid isomerization. As long as the water is rolling, you've got enough movement. It doesn't need to be a violent boil, which will cause splashing or, worse, burning on the bottom of the pan.

A bit of agitation also helps extract hop aroma after the boil. It's a good idea to keep your hop bag moving or to stir for a while if the hops are loose.

[daddies-beer-factory]

Lid fully off to prevent dimethyl sulphide (cooked cabbage flavour) !!!

[guypettigrew]

Thanks all

Today's boil was very vigorous. The lid was tilted on the boiler so all the steam could escape. Interestingly (to me, anyway!) the liquid lost during the boil was exactly the same as with a more gentle boil. About a gallon an hour. Must mean something, but I'm not sure what!

Guy

[Eric]

Lid fully off to prevent dimethyl sulphide (cooked cabbage flavour) !!!

It might be worth considering how many commercial brewers have completely open topped boilers and not a smaller sectioned flue, DMS has a boiling point of 37C .

[Kev888]

Yes I agree, in my experience a relatively modest gap or flue is more than sufficient to avoid DMS problems, not only does it boil off easily but it won't condense on the lid, which is heated well beyond that temperature by all the steam. In my case its actually advantageous, since the boil I get with the lid partially on is much more convincing than with a completely open kettle. I believe DMSO has higher boiling and condensation temperatures, but its still well below that of water.

WRT to the boil ferocity, you don't need to cause massive geysers but its better IMO to be over-vigorous than under. Unless theres a problem with boiling over, I wouldn't be concerned myself, though I can see it may be annoying in having to top-up towards the end of the boil. Perhaps you may get a slightly darker beer or more tendency for burnt-on wort if the element isn't low enough watt-density.

Theres a link between gravity and hop utilisation too, which I forget exactly, IIRC higher-gravity wort is better up until a certain point but I can't recall the details of if/when that becomes excessive.

Cheers
Kev

[tourer]

Yes I agree, in my experience a relatively modest gap or flue is more than sufficient to avoid DMS problems, not only does it boil off easily but it won't condense on the lid, which is heated well beyond that temperature by all the steam. In my case its actually advantageous, since the boil I get with the lid partially on is much more convincing than with a completely open kettle. I believe DMSO has higher boiling and condensation temperatures, but its still well below that of water.

WRT to the boil ferocity, you don't need to cause massive geysers but its better IMO to be over-vigorous than under. Unless theres a problem with boiling over, I wouldn't be concerned myself, though I can see it may be annoying in having to top-up towards the end of the boil. Perhaps you may get a slightly darker beer or more tendency for burnt-on wort if the element isn't low enough watt-density.

Theres a link between gravity and hop utilisation too, which I forget exactly, IIRC higher-gravity wort is better up until a certain point but I can't recall the details of if/when that becomes excessive.

Cheers
Kev

Question, would a wort be OK if the lid were left on and an extractor fan fitted to the lid??? I ask this question because it's impossible to move my boiler
(it weighs over 100 cwt or 60kg) outside and i dont want to fill the shed with steam. Sorry to encroach on the post but it is relevant.

[Eric]

Yes I agree, in my experience a relatively modest gap or flue is more than sufficient to avoid DMS problems, not only does it boil off easily but it won't condense on the lid, which is heated well beyond that temperature by all the steam. In my case its actually advantageous, since the boil I get with the lid partially on is much more convincing than with a completely open kettle. I believe DMSO has higher boiling and condensation temperatures, but its still well below that of water.

WRT to the boil ferocity, you don't need to cause massive geysers but its better IMO to be over-vigorous than under. Unless theres a problem with boiling over, I wouldn't be concerned myself, though I can see it may be annoying in having to top-up towards the end of the boil. Perhaps you may get a slightly darker beer or more tendency for burnt-on wort if the element isn't low enough watt-density.

Theres a link between gravity and hop utilisation too, which I forget exactly, IIRC higher-gravity wort is better up until a certain point but I can't recall the details of if/when that becomes excessive.

Cheers
Kev

Question, would a wort be OK if the lid were left on and an extractor fan fitted to the lid??? I ask this question because it's impossible to move my boiler
(it weighs over 100 cwt or 60kg) outside and i dont want to fill the shed with steam. Sorry to encroach on the post but it is relevant.

No problem other than the fan needing to be up to those working conditions as maybe half, or more, of the energy supplied will be lost from the top of the wort. It may therefore be worth investigating using a form of ventui.