Boil off question - water vs wort.

[Donoroto]

Ambient humidity also affects boil-off rate.

 

[Mont Y. Märzen]

Should be stable enough...It's 240V so I need to plug into the oven outlet, which means
room temps. Hoping a box fan in the window will help remove the majority of the steam
(I can position the unit close enough to the window I think). I can't see myself doing any
brewing in the summer...way too hot, and I can't provide any cooling for fermentation.

Air flow affects boil-off. So as long as you use it every time on the same speed, your estimation should be fine.

 

[Mont Y. Märzen]

Most brewing texts recommend Level 4 Vigorous.
Many brewers swear by Level 3 Rolling

A 240V system should have no trouble reaching 4. Most 5gal 120V systems struggle to maintain 3.

My friends who hold Level 3 always struggle with cloudy beer unless it ages for a month, even with finings. Mileage may vary.

I'd say go for Level 4, measure there. Be VERY accurate in pre & post boil measurements. Correct for water/wort temp.

 

[Mont Y. Märzen]

OK. I was under the impression that the boil should always be as vigorous as possible to flare off as much DMS as you can. What circumstances would require a less vigorous boil (besides potential boil over)? Thanks.

Less a DMS problem these days (but yes, judging homebrew, it still happens) as long as you leave the lid off, but less vigorous boils just don't make as good of a hotbreak or get the same reactions with the still suspended proteins. You'll also get less maillard reaction as well, but unless you want a straw-water beer, that usually isn't an issue.

 

[Mont Y. Märzen]

You need a source of ‘make up’ air, since the fan can’t depressurize the house by much. Leave the other window open so the air flows.

There will be steam. Enough to remove the wallpaper if you don’t deal with it.

Don't recall the maker, but look up "Steam Slayer". It is a lid with a blow off tube that you run water into on the side to condense the steam as waste water. That will drastically reduce your needed strike volume as you will lose less to the boil at any vigor level. You'll have to dial-in the proper heat level on your element to achieve the proper vacuum, but once you do, it will be gravy.

If you have to brew indoors, that is much preferable to a window fan.

 

[Mont Y. Märzen]

Your wort should be at a "rolling" boil, that is it should be actively moving. I also have an all-in-one system and get a similar boil-off rate with water or wort (the temps are essentially the same). Things that can affect boil-off rate are humidity and altitude (or barometric pressure).

With an active boil you should not see any significant scorching - I get a light brown layer on the bottom but it is rasily removed - a little Bar Keepers Friend or similar works wonders!

As does a little Phosphoric acid soak!