I keep my bottled syrup in chest freezers, in fact one is a freezer held at about 20F the other is a cooler held at about 35F.
I will be building a walk in cooler next year to hold my barrels. It will be based on using a "cool Bot" to operate an air conditioner. While I have not had spoilage without, I sometimes don't like packing a whole barrel of one grade at the same time. With the walk in cooler, I will feel far better about using half of a barrel and holding the other half in the cooler. As it is, I sometimes do half but then I fear loss and don't hold the other half for more that 3-4 days before bottling that too. If you do enough retail to pack a barrel or 2 into retail containers all at the same time you may not need or benefit from a walk in cooler. I have great sales from about Oct.-Dec. but in much of the rest of the year, especially in the hot months, my sales are slower.
I do not have 3 year old stock, I did have 3 barrels left from 2017 season just after the 2018 season, but they are gone, I now only have barrels with 2018 syrup in them, and the way sales are going I may be out by next Jan.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.