Comment by miduil

Yes, plenty - sometimes data centers are built together with apartment or office complexes for this particular purpose. Unfortunately that already pinpoints the core limitation, due to the low-temperature of the data centers. The higher the temperature difference is, the more affective heating becomes - with air cooled systems it requires preparation to ensure that can be used for heating.

Also data centers need physical space, and often - you need heating where there is not a lot of space (cities), and for "district heating" you need higher temperatures usually.