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Covering the pot during the boil.

Post #1 made 14 years ago
by 2trout
Ive been wondering about this as I hit my brew season here in Colorado.

My slow season at work is winter, so this is the time when I get to brew regularly. Ive only got 5 BIABS under my belt, and it seems the more I brew, the more questions I have.....

SO, this aversion to covering the pot during the boil. I do see a few potential problems with covering such as increased risk of boil over, but I also see potential pluses such as; less water usage due to reduced evaporation, possible indoor(garage) boiling do to reduced water evaporation/steam, less propane usage do to quicker boils and easier to maintain boils( remember, I'm boiling outside in winter :) ), and possibly,(a stretch here) increased hop utilization.

The major negative I read about is "off flavors" possible due to condensation dripping back into the boiling wort. I can imagine this with an aluminum pot/lid - maybe - . If boiling in a stainless steel pot w/ stainless lid, I really doubt the production of any off flavors. I don't get any funky flavors from a stainless pressure cooker; certainly a more harsh environment than my boiling pot.

Has anyone here experienced these off flavors from a covered boil :interesting: ? Just rambling out loud here.

trout
"All I know is that the beer is good and people clamor for it. OK, it's free and that has something to do with it."
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Post #3 made 14 years ago
by hashie
I don't cover my pot during the boil, so can't comment on first hand experience with off flavours. However the general consensus is that during the boil, DMS precursors are boiled off. Having a lid on your pot and allowing the condensate to drip back in to your pot is re-introducing those DMS precursors to your wort, increasing the chances of having beer that tastes off.

The off flavours are not from the lid itself.
"It's beer Jim, but not as we know it."

Post #4 made 14 years ago
by hbnath
It's also part of hitting the right SG...if you don't have some evaporation surely your SG will stay about the same?
I always have the lid off as Hashie says to get rid of DMS precursors too.
I guess it's like most topics on here....each to their own and you take or leave any advice!!!

Post #5 made 14 years ago
by joshua
Good Day, Just my .028Eu, Most of the "MM" the precusor of DMS, is gone from my boil is 30 minutes. My lazy heat source needed the lid, MOSTLY on. I cut 2 holes, in the lid, the size of #10 stoppers. This gives me a good rolling boil, with very few boilover. I still have the lid off center,as the wort boils down,to control boilovers. I may punch another hole and see if it will further controls the boil. The holes really vent steam and many different oders.
Honest Officer, I swear to Drunk, I am Not God.
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Post #6 made 14 years ago
by PistolPatch
My advice is not to play around in this area. There are many reasons. I'm away from home atm but I think I have a good link on this there and will try and dig it up (in about a week).

For now, remember that unless you cover your pot completely or almost completely, it will not alter the evaporation rate by a significant amount. You are better floating a lid on the wort to increase the boil vigour. And you want boil vigour to coagulate proteins (avoid cloudiness) and to drive off volatiles (whatever they are :)).

Short or whimpy boils often cause problems. Float a bowl as a first resort.

;)
PP
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Post #7 made 14 years ago
by Shifter
I certainly have no problem with boil vigor. My Urn lid has a serries of small holes about it's periphery which
allows for a generous escape of steam, coupled with the fact when boiling I use the bag as the hop recipticle the lid does not fit completely. So I manage to maintain a vigorous boil and egress lots of steam which presumably allows any nasties to disapate in to the atmosphere.
Appears to work for me.

Post #8 made 14 years ago
by joshua
Good Day, I have a question about the boil off values, I understand that at Higher Atitudes the boil temperature is lower(97-98C) and the Volume of boil off is much greater due to lower air pressure. Does this affect protein coagulation and Hop Bitterness??? It take much less energy to boil off at Higher Altiudes, and can be made at sea level with a standard vacuum system. I boil inside and would like to Get the steam out of the house.
Honest Officer, I swear to Drunk, I am Not God.
    • SVA Brewer With Over 100 Brews From United States of America

Post #9 made 14 years ago
by stux
Well, I experienced 20L boil off over 90mins with my 50cm wide pot...

All estimates were less I think

I'm at about 275M above sea level
Fermenting: -
Cubed: -
Stirplate: -
On Tap: NS Summer Ale III (WY1272), Landlord III (WY1469), Fighter's 70/- II (WY1272), Roast Porter (WY1028), Cider, Soda
Next: Munich Helles III

5/7/12

Post #10 made 14 years ago
by 2trout
I did forget about the DMS bit. I always felt that every extract brew I did had a similar DMS/corn back round flavor. Thanks for bringing that up Hashie, I dont want to go back to that flavor. Ill be leaving the lid off.

Joshua, Im at 5700' here in Colorado, and I seem to loose around 1.3-1.6G/hr. During my brew day Tues, I started my boil with 8.5G and ended with 6.5G.

So I wont be messing with the covering business. I just leave well enough alone.

trout
"All I know is that the beer is good and people clamor for it. OK, it's free and that has something to do with it."
Bobbrews
    • BME Brewer With Over 5 Brews From United States of America
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