Originally Posted by CaptnCully
I did this and the outside of the hops got really dry and crumbly before the center was even close to dry. Maybe I did not have enough air flow... temp was 128*
Too much heat...too little airflow.
Heat is applied to lower the relative humidity. This helps drive moisture out of the hop cone because the air has the capacity to hold more water. The big boys do it so they can dry their entire days harvest fast enough to be ready for the next days harvest to come in.
Temperatures above 100F drive out your oils and other flavors. Temperatures above 140F degrades the alpha acids that give you bitterness. So they bring in massive amounts of air, heat it up to increase its desire for moisture and then pass them over the hops.
In your case, you added heat but there wasn't enough air movement so you just cooked the hops.
Why wasn't there enough air movement? A fan's airflow is dictated by the speed of the blade, shape of the blade and the pressure drop imparted on it. Speed and shape are decided by the manufacturer. Pressure drop depends on how much stuff you are trying to push the air through.
The box fan you used can probably do 2,000 CFM without anything in its way. (0 pressure drop). Put one of those 50 cent furnace filters (Just a mesh of fibers that you can see through) and the air flow drops to about 800 CFM. Put a second and the air flow drops to 350 CFM. Throw some hops in there and your airflow is negligible. Use a high quality filter and air flow is zero. Without airflow, the water can't be swept away.
By far, the best and least expensive method is to lay them out about 1 cone deep in a dry area on a screen. If you want to speed it up, blow air across them. If you really want to speed it up, put a dehumidifier in the space to drop the humidity level.