The cold furnace ducts · Velstraven

A major room of chapter 4. When you walk in, the room card reads: Frost binds the archive door latch; the service door will not open.

Narrated walkthrough

The cold furnace ducts from its entrance — The cold furnace ducts: how to solve it

Getting there

Chapter 4, third upper floor. The north doorway of the Service galleries and reservoir hub.

What is wrong

"Frost binds the archive door latch; the service door will not open." Ice binds the latch inside a cold metal jacket. A reservoir of cold water sits high on the upper terrace. Its descending tube is broken, and its branch valve sends water to an unused wash basin.

What you can work

Source: The reservoir, 40 L of cold water above the rest of the network.
Heater: The ceramic heating shoe under the reservoir.
Socket: Two open sockets facing each other across a gap in the descending tube.
Branch: The branch valve. It sends water either to the wash basin or down to the door jacket.
Stop: The source stop, shut.
Panel: The jacket's inspection panel, shut over a ceramic latch-heating pad.
Pad: The latch-heating pad behind the panel.
Latch: The door latch, iced inside its jacket.
Door: The archive door.
Drain: Drains the return basin into lower storage.
Reading lamp: Optional light to read the room by: Handle toggles it, Heat lights it, Supply liquid douses it, Place light roots a lasting flame blossom in its cup. It works none of the room's fittings.
Reading shutter: Optional: Handle or Orient opens a high window for daylight from a second angle. It works none of the room's fittings.

Solution

A nudge

Heat goes into the water through its ceramic shoe. Only warm water (above about 35 °C) will thaw ice. The shoe keeps heating until you dismiss it.

The full solution

Climb the service stairs to the reservoir terrace. Aim at the Heater and cast Heat (Fire, Fire, Growth).
Heat goes into the water through its ceramic shoe. Only warm water (above about 35 °C) will thaw ice. The shoe keeps heating until you dismiss it.
What you see: "Heat enters the reservoir through its ceramic shoe." Within a few seconds the Source reads "Warm water fills the reservoir, above the rest of the network."
Aim at the Socket and cast Conduit (Growth, Water, Will).
The tube bridges the broken section, so water can run down the line.
What you see: "A descending conduit joins the exposed service sockets."
Aim at the Branch and cast Orient (Water, Will, Will) once (or Handle it).
The valve sends water to the wash basin by default. One turn sends it down to the door's jacket instead.
What you see: "The branch valve turns; its outlet now leads down to the door jacket."
Handle the Stop and wait about ten to twelve seconds.
Hot water runs down into the jacket around the latch and melts the ice from outside.
What you see: "The source stop opens." The Latch reads "Ice binds the latch inside its jacket; warm water in the jacket is thawing it." and then "The latch is free of ice."
Go down to the archive door. Handle the Latch, then Handle the Door.
With the ice gone, the latch draws back and the door swings.
What you see: "The thawed latch retracts." then "The archive service door catches open." and "The cold furnace ducts settled."

Other ways that work

Heat the latch directly: at the door, Handle the Panel open ("The jacket inspection panel changes access to the ceramic pad."), then cast Heat on the Pad ("The exposed pad warms the frost-bound latch locally."). About six seconds later the ice is gone; Handle the Latch and the Door. No water route needed.
Handle the Branch instead of Orient; it turns the same way.

Watch for

Heat first, water second. The reservoir holds 40 L, which runs out in about 20 seconds. Open the stop before the water is warm and cold water goes to the jacket first.
With the branch left on the wash basin, the water is lost there. Supply liquid into the Source adds 8 L per cast (cold, but the heater warms it), or restart the room.
Without the conduit, the stop reads "…the water spills at the broken section"; nothing reaches the door.
Heat on the outside of the latch jacket does nothing: "…the jacket keeps the warmth from the latch inside." Heat on the closed panel is shielded too.
Heat on the Pad is refused while the panel is shut: "The closed inspection cover shields the latch pad."
The terraces are linked by narrow stairs. Stepping off the upper terrace can drop you into a pocket you cannot climb out of; restart from autosave if that happens.

If it goes wrong

There is no failed state. A latch that is still iced only refuses: "Ice still binds the latch inside its jacket." Wait, or add heat.
Hold R for one second ("Keep holding to restart from the room's autosave"), or use the pause door "Restart from autosave", to put the room back as it was when you walked in: "Automatic room-entry save restored." Rooms you settled earlier stay settled.

Achievements here

Warmth in the Ducts: Solve the cold furnace ducts.

Spells used

Heat, Conduit, Orient, Supply liquid.