Originally Posted by neb_brewer
That all makes sense. I figured that the BrewTarget number was correct. I just didn't want to go with that without a confirmation from someone more knowledgeable. I haven't been getting great efficiency numbers with just adding 170 degree water. Hopefully increasing the temp of the water so that the actual sparge temp is 170 will help with that.
This is with batch sparging also...don't know if that makes a difference. If I decided to switch to fly sparging would I still heat the water to the 189?
No, fly sparging doesn't really work like that because the heat introduction would be so gradual. I believe that if you wanted to hit 170F on a fly rig you'd be best off mashing out and then using 170F water.
If you do notice a bump in efficiency with the hotter water, I would suggest looking into your process a bit. At sparge time, you should already be done converting.