Brewing with lid on boil kettle?

i watched an episode of brewing tv last night. They were doing a stove top extract boil. The kept the lids 1/2 to 3/4 of the way covering the pots all through the boils. Is this correct? I do extract with specialty grains, on a stove, exactly like they were doing and I thought leaving the lid on was a no-no. Am i wrong?

That should be fine. According to tests I’ve read, as long as you have 15% open space, you should be fine.

I thought that boiling realesed certain “unwantedables” from the wort/boil, and keeping the lid on made them stick to the underside of the lid, and reenter the wort? Is that untrue?

for what it’s worth. i leave my lid on half way. easier to keep a good boil that way (especially on windy days)

its true. IIRC, the theory is that the tiny amount on the under side of the lid is insignificant compared to the amount of steam leaving the kettle at a constant rate. and whatever does drop back into the kettle, evaporates first, and leaves via steam.

anyway. i still take off the lid, give it a good shake to release droplets, and put it back on (half way). and rotate it so the wet side is off the kettle. about every 5-10 minutes. i don’t know if that really helps. but gives me some peace of mind

+1 :cheers:

Im brewing tomorrow so I will be going with the 1/2 on 1/2 off lid trick with a shake and turn every so often! Thanks!

For an added bit of safety, you can increase your boil to 90 minutes. 30 minutes no hops, then add your 60 min hop addition (if you have one).