[kylekohlmorgen]

I still preheat because its part of my process. I've adjusted on the fly when I've forgotten the preheat water, but now its like second nature.

Old habits die hard, I suppose.

It also ensures I get the outlet valve clean  I've forgotten to clean that out once or twice.

[ultravista]

I do preheat my tun and also pull the grains out of the freezer far in advance to allow the mass to warm to room temperature. If a sunny day, the bag will sit in the sun ...

[morticaixavier]

I do preheat my tun and also pull the grains out of the freezer far in advance to allow the mass to warm to room temperature. If a sunny day, the bag will sit in the sun ...

unless you don't put any grain BACk in the freezer it's not really advisable to store grain in a freezer. Everytim eit warms up you get condensation and that can cause moisture damage to the grain.

Dry and cool is ideal. same with coffee beans

[DaveR]

I brewed last weekend and used my standard procedure of getting the strike water in the kettle just right (166 F). I poured it into my mashing cooler (no pre-heating) and added the grain. I used a fast reading digital thermometer right after mash in and sure enough the readings varied by as much a 6 degree F, even after stirring. I left it alone and 15 minutes later the mash had settled exactly where I wanted it to be -- 151 F. At 75 min it only dropped to 150.

I want this batch to attenuate down quite a bit, thus I'm mashing on the low end. I'm using WLP007, aiming for a fairly dry, light colored PA. Three days into fermentation it looks fine. BTW, I used some Fermcap since I was using a 6 gallon better bottle and was concerned about head space. My larger carboys were tied up. Krausen make it to the airlock anyway, but I've seen worse. FWIW I mashed 12 lbs of grain in 15 qts of water using my 5 gallon round cooler (about max for that unit). OG was 1.066. 

[DaveR]

strike water in the kettle just right (166 F).

Correction. Kettle water was 168 F.