Yes to the reservoir for crashing. If your run calculates 30,000 Btu/hr, you can go up to a 2.5 or 3 HP. If you stretched out the run time by lowering heat, you could get it done with a 2 HP, there is a different style for most chillers, 2 HP being the cut off for the smaller sizes and 3HP for larger sizes which are for sure more hefty. Cost difference could be as much as 3 thousand dollars.