Getting the coil connections leak free was much more difficult than I thought it would be. Twice I tried to tighten up the top compression fitting to stop a drip and just couldn't get enough leverage on the wrenches to turn the nut more than 1/16th of an inch. I finally removed the coil and did the tightening outside the kettle. After finally getting it all put back together, no leaks! The performance of the coil was similar with respect to temperature transfer. The maximum gain in temperature I could coax out was 3 degrees and I will still need to keep my HLT approximately 3 degrees above my mash temperature. One big advantage of the upgrade is that due to the low position of the coil I only have to add a small amount of cold water to cool the HLT after dough-in instead of adding 4 gallons to cover the coils then raising the temperature again. Another is that I have better control of the temperature of the wort as it leaves the coil by using the output ball valve of the pump. With the old small diameter coil tubing the flow was very restricted which is why I nearly always got a 3 degree gain. Now with the flow wide open the gain is only about one degree. By closing the valve I can increase the gain!
I also did a mash-out test. I increased the temperature of the thermo-controler to 175 and adjusted the ball valve to about 15%. With this combination I was able to bring 6.5 gallons of water in the mash tun from 153 to 168 in approximately 10 minutes. My plan during an actual brew would be to lower the controller to 170 when the MLT reaches 166 and open the valve to full with the lid off the HLT. I would then let mash-out recirculate for another 5 minutes before rigging the system of sparging. The temperature in the HLT should continue to rise up to about 170.
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