I used hot water the first time, then I saved those 3gal to use again. I have a 5gal aluminum pot for a water pot and a 3gal enameled pot for my milk. Its handles sit nicely on the edges of the larger water pot.
Update on last night's batch. Another possible failure. With less acid and less rennet (folloewed the instructions this time) the milk didn't set up nearly as fast or as well as the night before. I may have stirred the rennet in too much, I don't know. The pH looked better. Anyway, I was tired so I went ahead and cut the curds and heated them, leaving them in the 108F water for a couple of hours while I went to bed. I woke up at midnight at got up to drain the whey and hung the curds in cheesecloth. This morning I put them in a bowl and added salt. This time the product was very sticky. I tried microwaving a portion and it still didn't seem to want to melt and be smooth. It was time to go to work at that point so thats where things stand.
I'll get this eventually, although it may wait for some easier cheeses to be made. My first shipment of cheesemaking stuff is out for delivery so I'm excited.