Leaving lid on till boil is reached

[ramloese]

Is there anything to support the claim that leaving the lid on while achieving a boil (and thus minimizing boil time), and then of course remove it during boil, might lead to a poorer beer?

 

[flars]

No. I leave the boil kettle cover partially on all through the boil to reduce the amount of applied heat needed to maintain boil temperature. When using all Pilsen malt I periodically wipe the heavy condensation from the under side of the lid though this may not be necessary. Just a precaution to avoid DMS formation in the wort.

 

[mongoose33]

There have been all kinds of approaches to using the lid. I always use it while ramping up the heat prior to boil.

The only concern I ever see expressed is that the boil is supposed to get rid of DMS precursors, and the concern was that they'd condense on the lid and drip back in. People have tested that in their "not quite perfect but pretty reasonable" experimental methods and found no concern.

There are even some who found that boiloff seemed about the same with the lid on as off.

If you're new at this brewing thing, there are all kinds of other places to worry over than whether the lid on during ramp-up will hurt.

BTW: This is one reason why I like having an external thermometer on my kettle--I can tell when it's getting close to a boil, so that with just 5 or 10 degrees to go I remove the lid so I don't find myself inadvertantly getting a boilover.

 

[rekoob]

@mongoose33 +1

 

[mabrungard]

The only concern I ever see expressed is that the boil is supposed to get rid of DMS precursors, and the concern was that they'd condense on the lid and drip back in. People have tested that in their "not quite perfect but pretty reasonable" experimental methods and found no concern.

There are even some who found that boiloff seemed about the same with the lid on as off.

Hot wort enables DMS precursor (aka: SMM) to convert to DMS. There is NO need to boil wort to enable that conversion from SMM to DMS. However being a chemical reaction that operates under Arrhenius reaction rate, the hotter you get the wort, the more rapid the conversion to DMS. During this conversion period, there is NO need to vent the kettle. Simmering the wort while fully covered produces the same amount of conversion of SMM to DMS.

Once most or all of the SMM is converted, then its appropriate to vent the kettle and allow DMS to volatilize. DMS is highly volatile and it only takes about a half hour to fully expel DMS from wort. There is no need to vent the kettle throughout the entire conversion period.

PS: if the boiloff rate is the same with or without the lid, either the experimenter didn't measure accurately or the lid doesn't fit very well. It is the exchange with the atmosphere that governs the water loss from the kettle. A fully covered kettle will always boiloff at a lower rate than an open kettle.

 

[mongoose33]

Hot wort enables DMS precursor (aka: SMM) to convert to DMS. There is NO need to boil wort to enable that conversion from SMM to DMS. However being a chemical reaction that operates under Arrhenius reaction rate, the hotter you get the wort, the more rapid the conversion to DMS. During this conversion period, there is NO need to vent the kettle. Simmering the wort while fully covered produces the same amount of conversion of SMM to DMS.

Once most or all of the SMM is converted, then its appropriate to vent the kettle and allow DMS to volatilize. DMS is highly volatile and it only takes about a half hour to fully expel DMS from wort. There is no need to vent the kettle throughout the entire conversion period.

PS: if the boiloff rate is the same with or without the lid, either the experimenter didn't measure accurately or the lid doesn't fit very well. It is the exchange with the atmosphere that governs the water loss from the kettle. A fully covered kettle will always boiloff at a lower rate than an open kettle.

One example to which I was referring was here:

http://brulosophy.com/2016/10/31/the-boil-lid-on-vs-lid-off-exbeeriment-results/

In the piece was this picture showing the results of a boil w/ the lid off and the lid on:

I'm actually OK with the idea it doesn't matter, in terms of volume, whether you put the lid on or off. You're creating vapor pressure w/ the boil, and unless the lid is sealed--at which point you have a pressure cooker and DON'T DO THAT--then that vapor has to go somewhere. Out the edges around the lid is where it goes.

 

[chezhed]

PS: if the boiloff rate is the same with or without the lid, either the experimenter didn't measure accurately or the lid doesn't fit very well. It is the exchange with the atmosphere that governs the water loss from the kettle. A fully covered kettle will always boiloff at a lower rate than an open kettle.

Dang humidity variance I just lost a half gallon in my process because of lower humidity than previous brew....other conditions being consistent. I have always boiled with lid off....I am now probably changing that attitude.
How does one account for humidity in the boil off loss anyway?

 

[mabrungard]

While humidity is a factor, its not likely to be the major factor affecting evaporation loss. Wind speed has a huge effect on how much 'exchange' there is between your kettle and the atmosphere. Remember, the relative humidity is 100% near the surface of the boiling wort.

 

[homebrewer_99]

I have an old cardboard box (end flaps removed) that I place over/around my Bayou burner and brew pot to act as a windbreak.

 

[eric19312]

Dang humidity variance I just lost a half gallon in my process because of lower humidity than previous brew....other conditions being consistent. I have always boiled with lid off....I am now probably changing that attitude.
How does one account for humidity in the boil off loss anyway?

Watch your volumes and adjust your boil vigor to reach target end of boil volume.

 

[rhys333]

Is there anything to support the claim that leaving the lid on while achieving a boil (and thus minimizing boil time), and then of course remove it during boil, might lead to a poorer beer?

I leave the lid on during pre-boil heating, and I've never had an issue. I take it off completely for the boil, but I don't seem to waste any gas as I have one of those Tall Boys that boils with minimal heat applied. I boil off 1.5 gallons in 60 minutes, but I could dial it down to 1.