Mash tun heat loss

I am getting ready to make the switch from a cooler mash tun to a old keg for a mash tun and am curious just how much heat would be lost with a lid on and no insulation. I would think that with 20 or so lbs of grain the temp wouldn't drop all that much over the course of an hour.
Any thoughts

-Ander

any reason you wouldnt insulate? I lose about a degree in a 60minute cooler mash. Without insulation in a keg im guessing its gonna be a decent amount more than 1 deg/hour loss. Just wrap insulation around it...

Hard to quantify unless someone has intentionally let thier mash sit in a SS kettle and mixed it often to see what the temp loss actually ammounts to. (keep in mind the mash near the edges will cool drasitcally compared to the center)

Id say you will be looking at a noticeable loss, especailly compared to your cooler. You are correct, the center will not cool much, but the cold spots around the edges will be quite pronounced. (all that heat you feel on the outside of the kettle is heat escaping the mash) The outside of your cooler feels cool to the touch because you are losing, well, next to nothing. Compare that to burning your hand on the outside of a kettle MLT, and that shows you how much MORE heat you are losing.

Id either insulate the heck out of it, or plan for a RIMS or HERMS in the future. Heck, I still use a HERMS in my cooler setup.

POL Hit it on the nose this is my set up as well and in cold conditions garage temps 40-50 in the winter I still have to monitor temps. I use a fireproof piece of insulation (due to the burners on each side). Unless you plan on using a burner for direct firing and bump it when needed you should wrap it! If I did not insulate, my RIMS SYSTEM would struggle to maintain my mash temp.

I agree. You need to insulate it. I use Reflectix and put a blanket on the lid. With that, I don't lose much if any in warm outside temps, but in cold temps I'll still lose a degree or two (even with lots of grain).

I'd agree with "The Pol" as well. You will lose a substantial amount without insulation or a recirculation through a HEX.