Johnson Controls HF93B-1 Deep Well Air Release. The F93 Series Air Volume Controls for Deep Wells control the amount of air in the residential water storage tanks of deep well water systems. Deep wells are more than 25 ft (7.6 m) deep. F93 Series Controls automatically maintain air volume in the storage tanks of deep well water systems by allowing air to escape from the tank and into the surrounding room when the water level in the tank drops (increase of air volume). F93 deep well controls open the air valve on a fall in tank water level to bleed excess air from the tank at pressures up to 100 psig (690 kPa). The F93H has a minimum pressure release valve to avoid lowering tank pressure below 25 psig (172 kPa). Use this model on applications where water may be rapidly drained.