A kitchen in the Purple Palace: what Tianchu is named for
The Purple Palace is the walled enclosure around the pole star, and Tianchu is the kitchen inside its wall. The school takes three things from that: eating, supply, land that feeds people. It does not say a kitchen star makes a family rich; the name is about provision.
Chou fits the name. It is an earth mountain, the ox that pulls the plough, the hours before dawn when the kitchen is stocked and cold. A broad, fleshy, low Chou range with flat fields in front looks like the name. A thin, stony, barren Chou ridge does not.
Provision and land: how the school holds Tianchu against the ground
The school's rule is that the sky answers the earth. So Tianchu is held against the ground after the landform is judged. If the incoming range enters on Chou, the master wants a dragon that arrives full: a wide back, soft shoulders, soil deep enough to dig without hitting rock. Then Tianchu confirms a site that can provide. If the range is lean, the star confirms a lean site.
A peak on Chou is read as a storehouse hill, best rounded and heavy. Water from Chou should pool and linger near the site rather than drain off. The Cuiguan Pian gives dragon, cave, sand and water each a star; on Chou it is Tianchu, and it only confirms.
What this means on the ground
Tianchu is the third star clockwise from north on the Tianxing ring of the school's luopan, under Chou, beside Tianshi. From the seat of a grave, stand behind the stone and sight along it; from a house or shop, stand inside the door facing out. Take the sitting bearing three times with phones and keys off the plate.
Then sight each hill and the water mouth. A reading between 22.5° and 37.5° is on Chou, so under Tianchu. For a house, look at what stands on that bearing beyond the door: a market hall, a warehouse, a broad low block or a garden suits the name; a drain, a scrapyard or an empty lot does not.
Common mistakes
Kitchen is an easy name to run away with, so the first mistake is to read it as a verdict about money or food. The name describes supply; the ground decides whether there is any.
The second is reading with a phone or a flat compass. Those give a bearing, usually true north, and Chou sits between Gui and Gen, so a few degrees of error changes the star. The third is counting stars from a map or a satellite image before anyone has walked the ridge. The fourth is being so pleased by Tianshi next door that a peak on Chou gets rounded up to the noble star. Read the degrees, not the wish.
Questions people ask
What star is on Chou mountain?
In the Tianxing school, Chou mountain at 30° north north east carries Tianchu, Heaven's Kitchen, an ordinary star named for the kitchen inside the Purple Palace. The name points to food, supply and farmland.
Does Tianchu mean a site is good for farming or restaurants?
The name points that way, but the star only confirms what the ground shows. Broad, fertile, watered land on Chou with a full range behind it reads as providing; a stony, dry Chou slope reads as poor, whatever the star is called.
How do I tell Tianchu from Tianshi on the luopan?
By the degrees. Tianchu sits on Chou, 22.5° to 37.5°; Tianshi sits on Gen, 37.5° to 52.5°. A peak at 36° is on Tianchu, not the noble star. Read the number before the name.
Book Master Zhang for a site reading on the Tianxing ring, or come to the field course in Ganzhou and learn to sight the peaks yourself.