How hard should the boil be?

[sladeywadey]

So the consensus guys is that it is ok to boil with the lid partially on without any dms issues. Correct?

My boil off is around 18% lid off..

[Eric]

As soon as the sparge is complete I pop on the lid until it comes up to the boil. At that point the lid is removed and the wort stirred until it calms down when I would think most of the highly volatile components would evaporate. The lid is then replaced until a good rolling boil is evident when either the lid is moved over to allow steam to escape and keep the boil rolling well, or the IC is dropped in and the lid dropped on that leaving about an inch clear all round.
I don't see the point of taking off the lid to have a cooler boil yet loosing as much or more liquid due to less restricted evaporation as the undesirables are a relatively small proportion.

[DeadFall]

I've noticed the bitterness is smoother on the beers I've done with my 2.75kw element compared to the 2kw job in the same vessel. But that could be that I was also suffering cutouts with the 2kw job and blew it up bypassing the thermostat, so I was getting a few minutes rolling boil followed by five minutes of nothing.

[Kev888]

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.

Yes, it would likely be fine if the fan could cope with the heat and moisture etc. Although unless you have a loose lid or need for a particularly long or narrow flue then I'm not sure you would actually need to assist the steam etc escaping.

I've used 40mm waste pipe and later improved that to (100mm?) foil extractor ducting which worked well without assistance, running it down-hill to allow condensation to run out rather than collect or run back to the boiler. The main issue I had is that (like having a lid on a saucepan) it increases the risk of boil-over unless you can regulate the heat - my setup didn't allow that so I needed to be vigilant at the start of the boil and lift the lid if necessary; the tendency to foam up seems to decrease as the boil progresses though.

Some people use extractor hoods instead, and there you would need a fan (or an enormous flue) to draw in and capture the steam.

Cheers
kev

[Kev888]

As soon as the sparge is complete I pop on the lid until it comes up to the boil. At that point the lid is removed and the wort stirred until it calms down when I would think most of the highly volatile components would evaporate. The lid is then replaced until a good rolling boil is evident when either the lid is moved over to allow steam to escape and keep the boil rolling well, or the IC is dropped in and the lid dropped on that leaving about an inch clear all round.
I don't see the point of taking off the lid to have a cooler boil yet loosing as much or more liquid due to less restricted evaporation as the undesirables are a relatively small proportion.

Thats almost exactly what I do, too. If I take the lid off completely then the boil vigour decreases detrimentally, though probably it would matter less if I had far more heating power than I do.

Cheers
kev

[RobWalker]

So the consensus guys is that it is ok to boil with the lid partially on without any dms issues. Correct?

My boil off is around 18% lid off..

Providing you're using UK malts I would say yes. US Pale and Pilsner Malts can produce much higher levels of DMS, but UK malts will produce very little DMS.

If your only aim here is to reduce boil off, don't worry about it. You can add water back in post boil and reducing boil off won't have any positive effects on the beer, unless you have another reason to reduce boil off...

[sladeywadey]

Fair points Rob - I'd rather not have to keep adding water at the end if I can help it.