Thermodynamics. The exhaust temperature of the data centre has to be significantly higher than the temperature of the thing you want to heat, especially if that

Thermodynamics. The exhaust temperature of the data centre has to be significantly higher than the temperature of the thing you want to heat, especially if that heat is to be transported any appreciable distance. Otherwise, the heat will not flow in the right direction. With data centres these days trying to keep chip temperatures as low as possible, this really makes the temperature gradient very low. An alternative would be to pump in a little bit more energy and use the exhaust heat as a source for a heat pump.