Lid on or Lid off?

[Swiller]

This probably applies to all brewing methods.
My boiler like others has a lid is it best to leave it off
during the boil? I have heard if it is left on it can cause
off flavours by holding back things that need to be
boiled off?
Any advice would be appreciated.

[Kev888]

I have mine 'mostly' closed; it helps to retain the heat, but if I have it too far on then I get it all bubbling up (and out). As I understand it, provided steam can freely escape without having to build up pressure then you shouldn't be trapping the unwanted stuff.

Prior to this I tried it mostly closed but with various vent/extraction hoses - some worked better than others but I missed being able to control stuff by positioning the lid.

Cheers
kev

[Swiller]

Thanks Kev I usually keep the lid on
my boiler as it has vents to let steam
escape easily and not under any pressure
so I will carry on that way.

J

[EoinMag]

Thanks Kev I usually keep the lid on
my boiler as it has vents to let steam
escape easily and not under any pressure
so I will carry on that way.

J

You should really be taking the lid off, especially if you ever move to lagers, you'll need to boil off DMS or DiMethyl Sulph?ide or ate, can't remember which one it is but it's the smell/taste of cooked cabbage, and not something you want in your beers.

[Kev888]

you'll need to boil off DMS or DiMethyl Sulph?ide or ate, can't remember which one it is but it's the smell/taste of cooked cabbage, and not something you want in your beers.

Yes definately, but my understanding is that DMS is quite volotile so provided the steam can feely escape then thats more than enough to let out the DMS at the same time.

Cheers
kev

[Redimpz]

I go for lid on until it boils. keeps more heat in, it takes long enough to get to the boil without losing heat, once it hits boiling though I take the lid off and reduce the heat so that it is "rolling". tend to put the lid back on for chilling though so as to reduce the risk of anything getting in as the temp drops.

[EoinMag]

Definitely lid on until it boils, that not in question, it's the most thermally economical way to go, but once up to a boil the lid comes off. Everywhere I read says lid off and rolling boil, so that'd be my advice as it follows common knowledge, that said I BIAB which on the other side kicks common knowledge in the nuts, so YMMV.

[Kev888]

Everywhere I read says lid off and rolling boil, so that'd be my advice as it follows common knowledge, that said I BIAB which on the other side kicks common knowledge in the nuts, so YMMV.

Hmm, it may be that I need to investigate it again then - I was fairly convinced that it is indeed one of those common myths that have grown up, they do after all use mostly enclosed boilers in many breweries, but i've been wrong many, many times before so probably worth double-checking.

EDIT: BTW, this post from Aleman was what initially put my mind at ease about DMS; after that I did various searches and it appeared as long as the DMS/steam can get out happily nothing that I could find suggested how a partially closed lid would matter. Theres a lot of rumour though so its challenging to sort out fact from fiction - have you come across anything in particular that I could read up on it?

Cheers
kev

[jimp2003]

In John Palmers How to Brew on the web he says:

"DMS is continuously produced in the wort while it is hot and is usually removed by vaporization during the boil. If the wort is cooled slowly these compounds will not be removed from the wort and will dissolve back in. Thus it is important to not completely cover the brewpot during the boil or allow condensate to drip back into the pot from the lid. The wort should also be cooled quickly after the boil, either by immersing in an ice bath or using a wort chiller."

[boingy]

I boil with lid on and a small-ish steam escape pipe. No DMS problems - it is all driven off with the steam.

What I would say is that I always cool with the lid off. As the temperature drops I don't want condensate dripping off the lid back into the brew.

[jimp2003]

I brew outside on gas and leave the lid partially on mainly to shield the brew from the wind.

I would not put the lid on fully as I would be paranoid that it would encourage a boilover that you would not see until it came spewing out of the boiler.

[EoinMag]

I think the thing that would mostly concern me is the condensate dropping back into the boiling liquid, so you are just inefficiently removing DMS. Palmer as a source would not particularly sway me in either direction as he's hit and miss with his stuff anyway but a great basis for good homebrewing, just not eminently quotable.

[jimp2003]

I think the thing that would mostly concern me is the condensate dropping back into the boiling liquid, so you are just inefficiently removing DMS. Palmer as a source would not particularly sway me in either direction as he's hit and miss with his stuff anyway but a great basis for good homebrewing, just not eminently quotable.

He might not be eminently quotable but at least you agree with his views on this.....

[Lugsy]

I can only just get a 20 litre pan to boil on my hob (I know, time to look at a proper gas burner soon!) so during my boil I leave the lid partially covering the pan so that condensate can run off onto the hob (much to SWMBO's delight) and only cover fully for a couple of minutes at a time every so often to bring the temperature back up to a good boil. It's not ideal and I'd rather boil totally uncovered but I don't suffer from DMS as far as I'm aware. I cool in a bath of cold water with the lid fully on so the cooling wort isn't exposed to too many airborne nasties but I'll get myself an immersion cooler soon and then I'll need to chill uncovered but for a lot less time.

[Swiller]

Mmmm, I seem to have sparked quite a debate.
The reason for my original post is I made a pils
clone which has a slight chemical taste and wondered
whether it was down to keeping the lid on during the
boil. My boiler will boil with the lid off I keep it on
to reduce loss of wort by evaporation. I read sometime
ago that placing a plastic bowl or plate on top of the
wort reduces the surface area meaning less evaporation?
Maybe I will give this a go.