Is chilling the wort neccessary?

the recipe we're doing says to chill the wort in an ice bath to 80F within 15-20 minutes...the last recipe we did, we just dumped the wort into the primary which already had our cold water in it

so do we need to do a wort chill before going into the primary?

The idea is to get the wort down to a temp below 80*F before pitching the yeast. As long as the method you are using does that and without introducing bacteria and wild yeasts, you are fine.

Dumping the hot wort in enough cold water as you described is one way. Some people use ice, but if you do, you should make sure it is clean and not harboring harmful bacteria. Many people consider it better to boil water, put it in santized milk jugs, and freeze it rather than use commercial frozen ice.

Wort chillers are generally used by those who do full or almost full boils, since they will likely only have to top off with boiled water or clean ice and can't really add enough to aid in chilling.

The faster you bring your temp down, the better, because it helps you to get a good cold break, leaving most of the proteins that cause chill haze to precipitate out.

Check out the Cooling the Wort chapter from John Palmer's online version of How To Brew.

John Palmer's book is a great online resource for new brewers.

I'll just throw this in there so you can worry about it like I did. There is something called Hot Side Aeration that can happened when you pour hot wort. I had never heard of it until someone on this board mentioned it to me *gives Walker the evil-eye*

Anyway, supposedly if you splash your wort when it's over like 100 degrees or something (can't remember the actual temp) it can get aerated and cause a cardboard type flavor.

Now, I've tried several things to keep from splashing my wort into the bucket including dropping ice in my pot and siphoning from my pot to the bucket. Both approaches have their issues.

I've decided that I can't tell a difference and there are lot's of other things I need to worry about before I go down that road. Besides, that will all be taken care of when I go full boil with a chiller.

Yeah, on my first brew, I was so proud of myself for pouring my 130dF wort onto big chunks of ice in my fermenter bucket from about 4 feet up to get a great aeration. DOH!

The interesting thing about this hobby, or any for that matter, is that you learn great things over time, but usually in the wrong order. Learning about HSA prior to the concept of required cold aeration would have been nice. Kinda makes you wonder how many other things you're doing only HALF-right.

Bobby

Chilling the wort to a temperature that is compatible with the yeast is crucial. The faster you cool the wort the better your beer will be. Quickly chilling the wort reduces the time it will need to spend outside of the closed fermenter and exposed to potential contamination. Chilling also causes cold break. As the wort cools, more of the undesirable proteins coagulate and settle to the bottom as trub. The easiest way for the homebrewer to chill wort is to place the well covered brew pot into a bath of cold water. You will need to change the water a few times as it extracts the heat from the brew pot. The cooler your wort, the more susceptible it is to infection from bacteria and wild yeast. It will take about 1 hour to chill two gallons using this method. Never add cold water to boiling hot wort. This is the primary cause of ‘homebrew aftertaste’ in the finished beer.
Make up water is the term used for the water we need to bring the total volume of wort up to five gallons. It is a good idea to place this water in the refrigerator the night before brewing. The cold water will help bring the wort down to pitching temperature. I know, I just said don’t add cold water to hot wort. Once your boiled wort drops to below 180oF the risk of homebrew flavor diminishes. This is also the temperature where infection becomes a possibility.
Aeration of the wort is critical to good fermentation. This is the one and only time at oxygen should be mixed into the wort. The yeast requires oxygen to start the fermentation process. Remember, this is the only time in the life of your beer when oxygen is a good thing. Place the sanitized fermentation bucket on the floor with the lid off. Open your make up water and pour it into the fermenter. Allow it to splash around and pick up oxygen.

From what I've read and heard from Pope Jamil Z the undesirable production of DMS is the effect of the wort staying hot for to long.
Description: Tastes and smells of cooked vegetables/corn/cabbage or shellfish/seafood.

Cause: Bacterial infection can cause DMS, as well as covering up your brewpot during the boil. DMS is removed from the wort during the boil, so covering it up is obviously going to cause the DMS-laced condensation to fall back into your brewpot.

Remedy: Keep good sanitation procedures, and make sure to keep a rolling, uncovered boil when brewing. Do not cover your brewpot during the boil!
The lighter the beer the more noticable DMS will be although a little is sometimes considered desirable in some light lagers.

DMS is produced anytime the wort is above 140F. The idea is to get the wort below 140 ASAP. During the active boil it's being driven off, but as soon as the boil stops it forms and stays in the wort. If you can't get the wort below 140F in 20 mins, you can also boil for 90 mins to drive off all the SMS which is the raw material for DMS.
I started with a counterflow chiller in my 5gal days and it was perfectly adequate for that size batch. With 10 g batches it took too long so I switched to an immersion chiller and now my wort is to 68F in 20 min.
Checkout www.mrmalty.com

Seems like Ol' grog and Musthavbeer have nailed this one.

It is harder to cool wort that has cool water added to it. the greater the temperture difference the better the cooling effect. Then after cooling you can add your cool water to further cool your wort to pitching temps.

Cool, huh.