There is another factor which can influence the fan rate and that is the ammonia gas level. It should be 25 ppm or less. If the ammonia level is too high at the correct RH level, then increase the fan rate to dilute this gas. Fans on central plenums or on perforated PVC pipe ducts under the flooring in farrowing or nursery rooms can frequently be justified to hold lower ammonia levels and pull heat from the ceiling down to pig level. Another option to reduce ammonia levels is to use a pit additive.
Ammonia is a more expensive item to measure accurately.
This means purchasing a control which has wiring to handle the heater also. Set the heater to turn on when it drops 2F below your set temperature. Don't locate the thermostat in the path of the heater blower. Trained personnel is the last item to make this ventilation system work smoothly. The pork producer needs to be trained by the ventilation installation company representative or attend educational meetings to understand mechanical ventilation.