Wort chiller versus ICE chiller

I usually do a 5 gallon brew with approx. 3 gallon extract batch wort mixture in my brewpot so am adding approx 2.5-3 gallons of water ice after boil-off. Will this work as a chiller to bring the temp down for SG test and yeast-pitch? A true poor man's chiller. What say you???

If you're mixing equal parts of cold and hot then you can expect the temperature to split the difference. If there's a phase change involved (ice to water) then you can expect to come a little more to the cool side.

Assume 1 gallon of water at 200F and 1 gallon of water at 40F then you'll get 2 gallons at around 120F. You can do the math using the latent heat (if I remember my thermo correctly) for the energy required to convert ice to water then add that into the overall calculation if you are using ice.

Short answer, no I don't think you are going to get equal parts to chill a hot wort down to 70F. My first (and only so far) was done in a 100qt crawfish pot. I set the pot into a galvanized tub and ran the hose into the tub. This gave me a constant temp cool water bath and chilled my wort down to 70F in just about 10 minutes.

ya, like Jay said, you'd likely get quicker results if you use an ice water bath in your sink. Use a sanitized spoon to stir the wort and put more ice into the bath as needed. I was doing 3.5G boils and it would take me about 20-25 minutes to get down to pitching temperatures using a large bag of ice. The combo of chilled top-off water and an ice bath will get you there much quicker.