Sparge water 180 F ????

If I mash at 150, then step to 155, can I sparge with 180 F water to get the grains to 168 F in the sparging process and thereby get it to convert finally at around 158- 160?

And in the stepping process can I add boiling water to raise the temp, or is that so hot it will kill the process?

Not sure what you're asking in the first part, but I assume you're talking fly sparging, so I'll leave it to someone else...

For the second part, yes you can add boiling water to step it, but just be sure to stir well to distribute the heat.

Why whould you step from 150-155?

Yes, you can infuse any temp water as long as the equilized temp is below 170F.

I guess I am confused about the steps in temps for mashing...
but i thought that I needed to get the lower conversion sugars below 155 and the higher above 155? That's why I was thinking of stepping this way.

There's no need to do a step mash. You will get the results you want by mashing at 152 - 153.

-a.

No - mashing between 150-158 or so produces different flavor profiles. The higher the temp the more unfermentable sugars your going to get. Down in the 152-154 (maybe 155) range your going to get the most fermentable sugars out for a "dryer" beer. But once the conversion is done its done.

You sometimes read about people doing a mashout to get the grain bed up to near 170 so that the sugars are more soluble and wash out better. That is probably what your thinking of.

Mashout temperature also denatures converting amylases, fixing fermentability. If you double-up tasks and use your sparge liquor to raise the mash temperature to mashout levels, fly-sparging can actually increase fermentability, as it takes significantly longer to raise the temperature of the grain bed when fly-sparging as opposed to batch-sparging.

And yes, you can add boiling water to raise mash temperatures without fear of denaturing enzymes.

Bob

Sparge water temp depends on your equipment. My best advice is to dig out your thermometer, start with 180*F sparge water, and figure out how much hotter or cooler you need it to be based on where your grainbed ends up.

My Coleman Xtreme 70 cooler tun has a large heat capacity, so for 5 gallon batches my first batch sparge infusion needs to be about 190*F to achieve mashout. After that I can drop down to 180*F for the second batch sparge and the grainbed stays between 165*F and 170*F throughout the sparging process. When I was using an Igloo 36qt, it had a much lower heat capacity, so my sparge water was 180*F to 185*F for the first infusion and I achieved mashout.

When I fly sparge I do a mashout infusion based on BeerSmith's calculator. I start with 175*F water and by the end I end up with 185*F water to maintain 168*F since I lose heat during the sparge (I have the lid open, I don't have a fancy sparge arm).