I have a 10 gallon igloo round cooler and noticed a lot of heat loss. I initially wrapped the mash tun in a sleeping bag to keep the temperature stable, but I read somewhere that the lids are pretty much hollow so I drilled holes in the top and filled it with foam insulation. My first mash with the insulated top resulted in negligible heat loss over 75 minutes.
I'm building a mash tun soon and this will be the first thing I do to it if I use a cooler. very useful post
Thanks for the idea with the spray foam insulation. How many holes did you drill? And did you have to seal off the holes to prevent them from contacting water or are they ok with that?
The igloo cooler has raised sections that look like a Trival Pursuits wheel. I drilled a hole in the center of each one and put spray foam in them. It was my first time using it and it was way too many holes. If you are worried about water getting in you could put some sealant over the drilled out holes after the spray foam has set. It takes a day or two for it two firm up completely.
I was just having the same problem with my new Home Depot cooler I put together and used on my AG brew saturday. I went from 151 to 144 during the hour even after pre-heating the cooler. Still got my expected OG of 1.070 per the recipe, so I'm not complaining!
That government is best which governs the least, because its people discipline themselves. — Thomas Jefferson
Just drilled and filled my lid with spray foam following jhallorans idea. Of course I couldn't bring myself to drill any less than one hole per spoke. It was just too fun. Thanks for the idea, I can't wait to try this out in a few days.