Transfer to fermenter before or after chilling?

Hi,

Should I be transferring my wort into my fermenter as soon as I've finished boiling it in my pot?

Or should I let it cool first?

I can't decide because I imagine that leaving it in the metal pot with its loosely fitting lid too long might introduce bugs, but I'm also not sure about putting boiling wort into my plastic fermenter - might that warp the plastic and cause it to leach chemicals and off-flavours into my beer?

Also, how important is it to chill my wort quickly by putting it in icy water? I've read that this is recommended, but never really got a definitive answer on just how necessary it is.

Thanks!

You'll want to chill it as fast as you can, THEN transfer to you fermenter. It's not a right or wrong thing, it just reduces your risks.

I cool my wort before it goes to the ferm, and I too have read that the wort should be cooled quickly so that yeast can be added as soon as possible to reduce risk of contamination and other reasons that I can't recall. I would suggest checking out some sort of wort chiller, I personally like the DYI counterflow chiller that I made per instructions from a HBT thread I found somewhere in the DIY section a while back (copper tube inside of a water hose). When I would gravity feed the wort thru the chiller I could chill 5 gallons in about 15 or 20 minutes. Anyway, hope that helps.

As bruno and fatcock point out, you want to cool your wort as soon as possible. You could also go with an immersion chiller. They are easier to make and clean, but don't cool the wort quite as quickly. Mine cools a batch down from boiling in about 15 minutes, to about 70. The main reason is to reduce the risk of contamination. A slow cooling method will probably produce off-flavors, such as DMS (butterscotch taste). Also, cooling quickly will allow the haze causing proteins to fall to the trub layer. Hop aroma is also preserved more with rapid cooling.

If i need some added water to get to 5 gal (if i boiled too long) or did not get enough liquid from the grains i use some ice water to bring the temp down faster. When i was extract brewing i got pretty good at knowing how many pounds of ice + how many gallons cold water i used prior to put my wort in - all that happened in my ferementing bucket. now when i use partials or all grains i use a wort chiller in the brew kettle and then put the pot in cold ice water tub. 15-20 mintues im pitching my yeast