Hello, with regards to extract brewing, do you all use lids on your brew kettle or keep them on only during certain times of the brewing? Cheers,
no lids! Oh, except while it’s cooling to keep stuff out of it. 
-OCD
Keeping the lid on while boiling is a bad idea. Even with extract there is a risk of DMS (cooked corn and vegetable flavors and aromas), boiling drives this off, but with a lid on it’ll go back in your beer. In addition, if you keep the lid on you’re much more likely to get boilovers.
I recall hearing that as long as you have 15-20% open space on the top of your kettle you’ll be OK. So, lid partially off at least.
I only lay mine on the keggle opening for the last 15 minutes to sanitize it and I still leave it open by about 40%.
+1
all the commercial kettles have 10% or less on the vent, so I am not sure that we as homebrewers aren’t a little extreme on the lid usage.
True, but they have excellent ventilation and likely power vents.
OTOH, we aren’t commercial brewers so what applies tp them may not apply to us.
The main reason I stated earlier about the commercial breweries is that they cannot remove the lid and the condensation drips back into their kettle. I understand they may have a fan pulling on the kettle but they don’t have a way to remove the lid as we do, and their beers aren’t butter bombs.
Installing a flexible metal duct and power vent doesn’t seem like it would be difficult to make and give it a try. A metal flexible dryer vent pipe should work and be quite handy so you could swing it away anytime you wanted. 
Added: I think I’d put a trap close to the lid, maybe a couple feet away and drill a small hole in it so any condensed steam could drain away from the brew pot. jmo…
I think he means he wants to put a lid on the brew pot or keg. Connecting a powered vent to the lid is what I was talking about, not a vent hood. 
Man, I really gotta start reading entire posts… :
Thanks for all the replies! I’ll keep the lid off. Gee w-toe, think my apartment manager would let me do that? ;D
One way to find out!
The Saw! I saw the Saw.
I want on this board to embrace the saw, from early on.
Damn. I wanted to be the first to point at the saw…I missed that saw. You aren’t leaving it in the move, are ya?
Oh no. The saw stays with me, and will be forever part of Three Taverns Brewers.