Keeping the lid on when boiling

[belfastboozer]

I have been keeping the lid on my wort when boiling to get it to a rolling boil then taking off to finish the boil, I have read that this causes issues with off flavours, I haven't had any issues to date so to save time and gas would it be an issue to leave the lid on?

[Qs]

I think you get DMS issues if you leave the lid on. Thats why I leave it off anyway. I'd be especially wary of leaving it on if you're using pilsner malt. Also if you really want to keep the lid on try wiping the condensation off it as often as possible.

[Hop Bomb]

Yip - DMS. The steam needs some way to escape. Even leaving it open a wee bit would be better than not at all. You need to boil off the precursors to DMS & if you've the lid on the steam will just condense & drop back into your wort & give you much higher levels of DMS in your finished beer.

Why cant you get a good enough rolling boil on gas? Any pics of the boil? Whats your gas setup/kettle size?

[biertourist]

Larger commercial breweries do basically the opposite of keeping the lid on when boiling, they use "wort strippers" instead of boil kettles which look like large brewery boil kettles from the outside but inside they're a cone that has steam running underneath -a thin layer of wort is pumped over the top of the cone and this essentially "flash boils" the wort and drives off the volatile wort constituents that you want to remove within a couple of seconds.

http://www.krones.com/en/products/process-technology/wort-stripping-beer.php


Adam

[UpsidedownA (Andrew)]

If there's no issue with off flavours, then you're not doing anything wrong leaving the lid on for the first part of the boil. Evidently you get enough evaporation as it is.

[belfastboozer]

Yip - DMS. The steam needs some way to escape. Even leaving it open a wee bit would be better than not at all. You need to boil off the precursors to DMS & if you've the lid on the steam will just condense & drop back into your wort & give you much higher levels of DMS in your finished beer.

Why cant you get a good enough rolling boil on gas? Any pics of the boil? Whats your gas setup/kettle size?

I have a 7.5kw gas burner it doesn't have any prob getting the boil going or rollin, I do a 26.5 litre batch at a time

[belfastboozer]

I read that some brewers use a bowl the same diameter of the boil kettle with a small hole cut in the top

[Khannie]

I read that some brewers use a bowl the same diameter of the boil kettle with a small hole cut in the top

Tell me more about this?

I don't think there will be any issues with DMS if you're just getting the wort up to the roiling boil. That was the original question, right? I wouldn't leave it covered the whole time, but I leave mine partially covered and I haven't had any issues yet.