Answer:
Yes facing of the main door should be decided through Vastu. If facing of main door should not according to Vastu, than many problems are facing by house owner. Such as enemy, fire,economic,accident cases and others.
So main door should be keep in North-East and East-North facing doors are most suitable for flat/house. East to East North East direction and North to North North West is the best direction of facing main door. .
For example;