The heavy timber frames the workers had been assembling were nothing compared to what Su Xiao had in mind for the central pavilion. They needed monoliths- four colossal ironwood trunks that had been curing under heavy tarps.
"The weight is too great. We aren't lifting those by hand, we let the iron do the work"
Mu Wei rolled his sleeves as he directed. Using the thick ropes and high-grade pulleys, he set up a classic block-and-tackle system, anchoring the heavy lines to a sturdy tree uphill. His voice rang out again,
"Group one, walk the line backwards when I give the signal."
He took his position at the base of the deep stone plinth to guide the pivot.
"Group two, handle the stabilizing ropes on the sides. Steady and smooth. Heave!"
With a collective, rhythmic pull, the workers moved. The iron pulley spun around effortlessly multiplying the men's strength. The foot of the giant ironwood pillar slid forward with a solid thud that echoed through the camp. The massive timber rose smoothly into the sky, cutting a sharp magnificent silhouette against the mountain.
Within two hours, all four pillars stood perfectly vertical, aligned with geometric perfection. The sheer height and wide spacing left the workers in tremendous awe as they stared at the well-balanced, and elegant structure stand firm.
At the abandoned building, Yan Huai had fallen asleep after the medicine took effect. Su Xiao grabbed the medical instrument to wash off the dried blood and prep a cold compress for his fever. She didn't use the water from the space to avoid risking exposure. Instead, she walked to the back of the property where the mountain rock face meets their land. As she walked to the shaded rocky recess behind the main foundation line, she heard it. There, hidden beneath a ledge of frost-rimmed slate, was a crystal-clear mountain spring. She brushed away a layer of the crisp snow to see a a rhythmic bubbling of the spring bursting straight out of a deep fissure in the bedrock.
She dipped her fingers in. It was biting cold, but completely liquid and unfrozen. It was running with an aggressive, lively current. Because the water was under high pressure deep within the mountain and constantly moving, the heart of the spring couldn't freeze. As she stirred the chilling water and watched it flow over the rocks and disappear into the frozen dirt, she had an epiphany.
In ancient times, people carried water in heavy wooden buckets through the snow. It was exhausting and dangerous, and buckets would freeze overnight. She looked up at the massive ironwood pillars raised high and notes that the spring is physically higher than the house's foundation. She pulled out the scrap parchment and charcoal stick she carries with her and starts sketching a dual-pipe layout.
If she connects terracotta pipes to the high spring source and buries them underground, the natural slope will create enough water pressure to push the water directly into the house without a single pump. The problem was how to keep it from freezing?
If water sits still in a pipe during winter, it expands, freezes and cracks the pipe, ruining the entire foundation. Just then, she had an immediate idea. She could use geothermal method. The trenches will be dug deep-well below the mountain frost line, which is where the depth of the earth stays a constant, unfrozen temperature.
She maps the water intake pipes to run directly alongside the hot smoke flues of the heating system which would be dug alongside it. The radiant heat from the floor-heating system will wrap around the water pipes like an electric blanket, ensuring the water inside stays warm, and completely liquid even in a blizzard.
That way, they had access to hot water in the cold and cold water in the summer. To prevent the water from freezing at night when the house is asleep, a "bleed valve" is added for an overflow outlet in the kitchen and bathroom area. By keeping a tiny, continuous trickle of water moving through the pipes and draining out,the water never stays long enough to freeze as moving water doesn't turn to ice.
For the heating system, she didn't plan to build a fireplace in one room and leave the rest of the house freezing. It was also impractical to have a fireplace in all the rooms which is why she planned to use her knowledge of thermodynamics, conduction and convention to build an integrated subterranean network called Dikan.
It was a floor flue system but it's biggest flaw was smoke stalling and carbon monoxide poisoning. If a flue pipe cracks or the draft falls, the rooms would be filled with deadly smoke. The pipes cannot be perfectly flat, instead, it slopes upward at a tiny, strict three-degree angle from the outdoor furnace. The furnace was best situated outdoor to avoid staining the high timber eaves or choking them in sleep. To heat the massive house, it needs to be fed heavy logs and cleared of ash constantly. This would shatter the elegant aesthetic of the house as the servants haul bark-peeling logs through the living spaces.
The mountain provides a natural intake draft, pushing the clean heat through the pipes which the deadly soot vent safely in the canyon. Since hot air wants to rise, the slight incline forces the draft to keep moving forward naturally even through tight bends. During the summer, the valve can be shut off ensuring the house doesn't turn into an oven. If the hot air moves too fast, it could crack the stone. So the pipes branch out into individual rooms which slows the air down and forces it to linger under the floorboards just long enough to transfer into the stones than rushing straight to the chimney.
The three systems took two lanes. The center lane for the fire as they generate a massive amount of heat. The right lane for the water parallel to the heat flue, separated by a safe, six-inch layer of packed sand and gravel. The sand acted as a regulator just enough to keep the water from freezing, but not too much to its scalding. The last lane was for the drainage system.