I’ve been monitoring my mash and realized I was losing heat in the mash tun over 60 min. I brew in a 10-gallon Gott (orange round) cooler. After reading a tip here, I insulated the lid with spray foam insulation. That didn’t seem to help much at all - on my last brew, I lost 4 degrees over an hour.
I preheated with very hot water, shot high on my strike temp, and adjusted with ice cubes until I hit my mash temp. I stirred very well and checked it over the course of 5 min or so, then put the lid on tight. I threw 3 blankets over the top to hold in heat, and still lost 4 degrees! This is really frustrating.
One thing that could be a factor is that the sides of the cooler seem to be separating. There is a bulge running vertically up the inner cooler wall, where it’s separating. I think this is from dumping the hot water in.
Should I just retire that cooler and buy a new one? That would be a bummer, because it’s still in really good shape. I guess I could also start doing a small infusion about halfway through the mash. Let me know what has worked for you.