The SMSCOM Twin Fan 4.5A & 7A Mk2 controllers represent a real step forward in automatic temperature control. Unlike other controllers that simply shunt fans from idle to full speed after the temperature is exceeded, the Twin Controller automatically calculates the exact running speed for your fans to maintain the temperature you set. This new method provides more accurate temperature control, limits fan noise and guarantees negative pressure inside the room. Simply plug in your fans set the temperature and the Pro Twin Controller will take care of the rest.
Please note: Though digital fan speed controllers (like this one) are a very cost-effective solution, they may generate a humming sound, and in particular when attempting to run at very low speed with smaller extraction/intake fans. This is an unavoidable consequence of using pulse width modulation to regulate fan output. We highly recommend our SMSCom Hybrid Fan Speed Controllers or the Rhino Silent range of fan controllers, which instead use heavyweight transformers and run completely silent.