Beersmith2 water volume issue

So I have been using iBrewmaster for a while now. I used it to dial in my system and when I use water volumes for mashing, sparging, and preboil everything goes very smoothly. So smoothly that I hit all of my gravity numbers on the nose. I recently purchased a new laptop and decided to buy Beersmith2. I created a new profile for my equipment and transferred all the specifics of my system over for example mashtun deadspace, kettle trub loss etc... So I have now brewed twice using Beersmith's water calculation and both times my preboil volume has been approximately 1 gallon short. Anyone have any ideas as to why this is? Nothing from my brewing process except using BeerSmith2.

One gallon high or low? First thing I would check is deadspace vols for mash tun and kettle, then look at grain absorption, and then boil off rate

JeepDiver said:

One gallon high or low? First thing I would check is deadspace vols for mash tun and kettle, then look at grain absorption, and then boil off rate

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Sorry I meant short. I have everything set the same as the settings I have in the iBrewmaster app. Later this week I'm going double check my mashtun dead space but I highly doubt that it would be the culprit