What is mulank, and why does it carry less weight than rashi or the birth chart in choosing a door?
Mulank is the digit sum of the birth date: born on the 1st it is 1, on the 11th 1 + 1 = 2, on the 13th 1 + 3 = 4, on the 18th 1 + 8 = 9. Indian astrology gives it little weight because India runs by tithi, not by date; if dates mattered, tides, amavasya, purnima and eclipses would fall on fixed dates. Doors by mulank follow the planet of each number (1 Sun East, 2 Moon North-West, 3 Jupiter North-East, 4 Rahu and 7 Ketu South-West, 5 Mercury North, 6 Venus South-East, 8 Saturn West, 9 Mars South), but the rashi and the birth chart should decide.
Related questions
Mulank 4 and 7 point to a South-West door. If Rahu is exalted in the chart, can one keep a South-West main door?
It has been seen that people whose Rahu is exalted, at a good degree and giving good results, had South-West doors without much trouble. Even so, a South-West door should be avoided. Where one exists, do the main door usara with seven sea-salt lumps given in this class, which gives very good results.
The kundli chart was shown with directions. How are those directions used, and what can a kundli tell about a house?
Go by the houses, not the numbers written in them: the top house is the 1st house (East) and the 4th house is North. If the planets on the North side are strong, the North direction is very good for the person. A kundli can even reveal where a person's house is, where its door is, how many windows it has and where a nearby river, pond or temple lies, so a map of the house can be drawn without seeing it.
Are three doors in a straight row inauspicious?
They can be either. In the South and West, from where negative energy comes, three doors in a row on padas where doors should not be are inauspicious. In the North and East they are auspicious: temples, all built facing North or East, have three or five doors in a row, as do royal palaces, so the blanket belief that they are bad is a myth.
Can doors be opened anywhere by vastu, or must the birth chart be checked?
Check the birth chart. If the Sun in the chart is debilitated and you forcibly open an E3 or E4 door, it will be wrong and not appropriate at all.
Do the directions of the kundli houses shift when the rashis or planets in them change?
No. The 4th house is always North, the 1st East, the 10th South and the 7th West, with the sub-directions between them. Like water flowing in a river, planets and rashis keep moving, but the direction a house represents stays fixed whichever planet or rashi comes into it.
Do we need to know the facing of the house to take its degree?
No. The facing is the side of the main door, opening or road, and using it is only one easy way to read the degree. What matters is to find where North lies; once one direction is known, the rest follow at 90 degree steps.