Sandustry Thermal Buffer Guide: Heat, Cold, Lava and Cinder

Understand the machine's job before placing it

The Thermal Buffer turns temperature into a manageable factory resource. It can collect heat or cold and support processes that need a stable thermal condition. Its useful capacity is therefore not only physical space: the direction and amount of stored temperature determine what the next input will do.

Treat a hot buffer and a cold buffer as different operating states. Label the intended state and isolate incompatible sources. A buffer crossing through zero may stop producing the expected result even while materials continue to arrive, so temperature should be observed alongside material flow.

Follow the documented input and output rules

The official page documents interactions with Fire, Lava, and Snow. Update #3 adds the current Lava rule: when the Thermal Buffer is cold, meaning its temperature is negative, Lava adds less heat and turns back into Cinder instead of being fully consumed. The returned solid needs somewhere to leave.

The phrase less heat is comparative, not an exact rate. Do not publish or design around a guessed number. Measure the starting temperature, the amount of Lava introduced, the ending temperature, and the Cinder returned in a controlled v0.5.6 cell. Repeat only after restoring the same starting condition.

Build a serviceable layout

Give Lava a limited input pocket and Cinder a separate gravity or conveyor exit. Keep the temperature source serviceable so Snow, Fire, or another documented input can be stopped without opening the Lava path. Provide containment that v0.5.6 Lava does not destroy.

Install an upstream shutoff and leave free space around the output. If Cinder accumulates against the buffer, the material cycle can stall even though temperature remains available. Keep artifact-room experiments separate because Update #3 fixed a case in which a Thermal Buffer consumed Lava while surrounding terrain self-healed.

Measure sustainable throughput

Treat Thermal Buffer as one boundary in a longer chain. Start with empty or recorded buffers, count how much heat or cold sources, including controlled Lava reaches the input during a fixed interval, and compare that with stored temperature and returned Cinder under the v0.5.6 cold-Lava interaction leaving the output. Record material still inside the chamber. A growing reserve before the machine identifies an intake or processing limit; a growing reserve after it identifies a collection or destination limit.

Do not infer an exact rate from a short animation. Let startup material clear, repeat the interval, and test again after saving and loading. If supply arrives in bursts, record both average flow and the largest burst. Add parallel capacity only after the same boundary limits two clean observations. Otherwise extra machines can hide a routing fault while consuming space, power, heat, cold, or scarce construction resources.

Diagnose the first failed boundary

If Lava disappears without returned Cinder, verify that the buffer was still below zero at the moment of contact. If Cinder appears but the process slows, inspect output clearance and whether repeated Lava input has warmed the buffer toward zero. Recreate the starting temperature before comparing batches.

If behavior changes only inside an artifact room, confirm v0.5.6 and reproduce it in an ordinary test cell. This distinguishes the special self-healing environment from the general machine rule. Preserve the affected save before digging or exposing more Lava.

Apply the v0.5.6 version notes

The negative-buffer Lava return is new in v0.5.6 and supersedes older explanations that treat Lava as fully consumed in every Thermal Buffer state. The same patch raises Lava density to 200 and lets it destroy Fluxite, Redsoil, and Strataform, so both input routing and containment need review.

Update #3 also fixes the artifact-room self-heal interaction. Remove old workarounds one at a time, test a small batch, and reload the save before declaring the route repaired. A current-version recovery copy should remain available until the line completes a normal long run.

Validate the design in a small test cell

Build one isolated Thermal Buffer with a limited input sample, visible output pocket, and a way to stop supply. Label the game version and active mods. Observe the expected transformation, any byproduct, where each pixel settles, and what happens when the destination fills. Then clear the cell and reverse the loading order if two materials share space. A repeatable small test gives a stronger design basis than a screenshot of a large factory.

After the test passes, copy the geometry into production while keeping access to the input, output, and removal controls. Leave enough room to inspect or drain the machine without opening a neighboring line. Recheck the route after patches that mention the machine, its materials, density, heat, fluids, energy, or building events. Keep the prior measurement with its version so a future change is visible instead of becoming an unexplained slowdown.

Use the pre-launch checklist

Before opening full supply, confirm that the input really is heat or cold sources, including controlled Lava, the planned result is stored temperature and returned Cinder under the v0.5.6 cold-Lava interaction, every required power or temperature connection is active, and no incompatible material can enter. Verify output clearance, overflow capacity, a shutoff point, and a safe path for the player. Take one recovery save before connecting a rare or destructive input.

During the first long run, compare starting and ending inventory at every boundary. Watch for material trapped inside building cells, a mixed network, a full destination, and a reserve that only delays failure. If the line remains balanced through its normal burst and restart conditions, record the observed rate and promote the module as the factory's current versioned standard.

Field facts

Troubleshooting

• Returned Cinder blocks the input.

  Stop Lava, clear the dedicated Cinder route, and reopen a limited feed only while the buffer remains negative.

• The same Lava batch adds a different result.

  Compare starting temperature and game version; restore the same negative state before measuring again.

• Artifact-room behavior differs from a test cell.

  Confirm v0.5.6, preserve the save, and isolate the room-specific self-healing interaction from the normal buffer rule.