i see most wort chillers are an immersion type. would it not work to circulate the hot wort itself through an ice bath? some years ago, 15 or so i used to homebrew. at that time i had access to scrap kegs aplenty. i took one, cut the top out, patched the holes and installed 50 ft of coiled 1/2" copper line with a port on the bottom  to drain the line. my intention was to fill the keg with ice, water and rock salt to keep the temp of the water low and drain the wort from the boil kettle through the coil to the fermenter. flow is easily controlled via a valve. i will have a modified gravity fed system with pumps. any pros/ cons/ feedback on such a thing?

It can work, look at plate or counterflow chillers.  The problem with your idea now is an old keg is $40-50 in most places, and the copper and fittings you would need are going to run about $40 as well, and that's BEFORE you do any labor to it, so you might as well buy a plate chiller for $90-100.  

Personally I use an immersion with a pump that recircs and whirlpools the wort.  This works really well, but a pump will set you back $150...I like to do the tinkering too, so if that is what you WANT to do, go for it :)

Plate chillers are the way to go, you have to worry about clogging from trub but that's easy to control.

I tried it, but hot wort is just too hot.  Immersion chillers still take a while with cold winter water running through them.

plate chillers, can run from the hose or a recirc pump with ice water.



either way they are better than a immersion chiller

So you guys that use the plate chillers, how much of an issue is trub? I built an immersion chiller and really would rather upgrade to plate chiller. But from what I have heard, the plates can get really tough to keep sanitary and clean.

There's several ways to mitigate it. The most popular is the angled pickup tube which is fairly effective but I prefer a "bazooka screen" along with a whirlpool for a few mins to let all the trub collect prior to running it through the chiller. I've had a couple of problems with clogs, (brewing an IPA with whole hops,) over the years but nothing major. Some guys prefer hop bags which contain most if not all the hop pellets/leaves but you loose a little IBU so add 10-15% over recipe.

I use a 300 mesh hop spider



when i first run, let boiling wort go through to kill anything not dead, the chill run wort done to 65 degrees.



when I'm done, I backflush with hot water a couple times, then drain



before i use it, I dump it into a bucket of star san



Ive haven't had a problem with cleaning or trub.



Before i got my hop spider hops was a problem



 

So the addition of a hops spider might be helpful then. Any good recommendations on how to build one or where to buy good ones? I have seen the PVC with steel mesh, but I don't have the biggest vote of confidence for that setup.

http://utahbiodieselsupply.com/brewingfilters.php





expensive but they work awsome. They also work for filtering any grains that get into the wort from the mash tun.



I used panty hose for a long time, but this is so much better

Interdasting.....They are quite expensive, I take it you have one? Build quality looks pretty good, true?

I'm poor folk so this is what I did:  HopTaco  Been working for a few years with a pump and shirron plate chiller

brick shit house quality.



Its probably tied for #1 or 2 of the best brew accessories I've used.



10 gallon batches with 12oz of hop will fit no problems

its SS so you can clean it with normal cuastic agents if needed (let hot break foam on it).

No dumb ass funnels/ nets/screens/ to dick with or sanitize. Remove it after boil, dump hops, spray with water from the hose, use again.



Screens that are in the kettle have to be removed to get all the shit out and its a pita to wash around. It also doens't slow down or get stuck when all the hops builds up-seen it happen. Since you just lift out, its easier to clean.



lastly you can use it for screening other processes in the brew op if you want.



I have the 6x14 that works in my keggle, but I would go bigger say 8x16 since I've moved to even larger batches and I want to try whole leaf.



Not required but a good investment none the less.



 

A plate chiller will work for your needs. I use an immersion chiller and I love it. I get ice water in a bucket and use a water pump to create a continuous flow of ice water through the chiller. This works great for my needs, but a plate chiller is a huge upgrade.