Martin has 2 great points. I started with a Therminator when they first came out, but it can't cool the wort any colder than your tap water. So in the Summers, when I brew lagers, I got a Duda 20-plate chiller that I put in-line. The first chiller gets tap water and the second gets ice water pumped through it with a little sump pump. Works like a charm.Tom,
And I highly recommend placing a thermometer on the wort output and use valves on both the water and the wort so you dial in the wort temperature.
So if you live in the Great White North, I would recommend one of the 20-plate chillers. If you brew sometimes when your tap water is warmer than you want the wort, get a second 20-plate chiller. It's still a lot cheaper than a Therminator or a Chillzilla.
I am wondering if the 20-plate chiller is easier to clean than the 30-plate chiller. The more plates involved worries me about getting trub, break material, and hops trapped w/in the unit. Have you had any problems cleaning the unit with PBW and/or back flush setup? I also live in the Denver area and would like to buy only one chiller. I am thinking about getting the B3-23A 20 Plate Beer Wort Garden Hose Chiller with 1/2" male NPT so I can add quick disconnects.