I used a full tablet of vegetable rennet on a gallon of storebought whole milk (with 1/8tsp of CaCl2 sol'n). I wasn't taking any chances that the milk wouldn't coagulate well! Hopefully the cheese won't be bitter, I figured since it was boiled in whey that it would be OK. Anywa, I got a very nice coag in about 40 minutes. I cut, let the curds heal then warmed to 105F slowly. I cooked there for 20min with minimal stirring that didn't break up the curd badly. Then I transferred to cheesecloth in a colander for a short drain before pressing under 20lb of weight in a basic cheese mold. I flipped the cheese after that and pressed another 20 minutes. I cut the cheese in half and then quarters and it held togehter very nicely. Heated the whey to 190F nd added the chunks, all eight pieces were floating within 10min. I stewed them at 180F for another 15min, they shrank quite a bit which I expected. I can't imagine that a block of soft cheese slightly under an inch thick would need to be cooked for an hour before it reached temp internally.
After I was done stewing the haloumi, I added some vinegar to make ricotta. Looks like it worked too. The haloumi is brining in the fridge now, I plan to pan fry some tomorrow night.