Cornish Boiler

The Cornish Boiler is the entry vessel: one flue in an iron or steel shell, 800 L of water and steam together, 32 L/s of steam out, and a choke pressure of 5 atm. It is a multiblock, not a block: a brick firebox with a hatch door, a plinth, a vessel raised in three stages from the block you place, and a pipe outlet for the exhaust, all inside a box 3 wide, 3 high and 8 long. This page is the build and the first firing; the operating numbers are on Boilers.

#	Colour	Name	Matches
1		Cornish Boiler (block)	ppex:boilercornish*
2		Pipe Passthrough (Straight)	ppex:pipe-passthrough-fire-*
3		Pipe Passthrough (Bend)	ppex:pipe-passthroughbend-fire-u*
4		Fireclay bricks	game:claybricks-good-fire
5		Empty (air)	game:air*
6		Empty (air, or a pile of coal)	@(air|coalpile)
7		Reserved space (kept clear)	exlib:structurefiller
8		Iron hatch door	game:cokeovendoor*
9		Pipe Outlet	ppex:pipe-outlet-fire-u

Every block is drawn in its default orientation: the layout carries no facing data, so the build order below names the facings.

Materials

Block	Cells
Cornish Boiler (block)	1
Pipe Passthrough (Straight)	2
Pipe Passthrough (Bend)	1
Fireclay bricks	33
Iron hatch door	1
Pipe Outlet	1

The site

Clear a box 3 wide, 3 high and 8 long before you place anything: 2 cells at the near end for the firebox and its door, 4 for the vessel, and 2 more at the far end for the exhaust and the back wall. The floor of the firebox sits one level below the boiler block, so the box starts one cell below it and reaches one cell above.

Snow counts. A snow layer over any cell of the footprint reads as a block, not as air, and will hold the structure incomplete with nothing obviously wrong.

Orientation

Stand where the firebox is to be and place the block in front of you. The vessel rises away from you; the two cells you are standing in become the coal slot and the door, the door at the far one. Get this wrong and the whole thing has to come down: there is no rotate.

Hold ctrl and shift and right-click the block at any point to outline what is missing. The projection shows the empty cells and the chat lists them by name and count, so "still needed: 6 x Fireclay bricks" is a shopping list, not a riddle.

Build order

1. Lay the water line first. It runs under the firebox floor, where nothing can reach it later: a Pipe Passthrough (Bend) in fireclay, turned up, directly under the boiler block, and straight fireclay passthroughs running from it out under the coal slot and the door. Carry the pipe on from there to wherever the water comes from.

2. Wall the firebox. Fireclay bricks around those two cells, floor, sides and roof, with the hatch door in the middle of the end wall at the boiler's own level. Leave the cell between the door and the boiler empty: that is where the coal pile goes.

3. Set the exhaust. A fireclay Pipe Outlet facing up, at the far end in the vessel's upper row, with the cell directly below it left as air. Stand an ordinary chimney on it, or run a pipe from it to a smoke stack.

4. Brick the plinth and the back wall. The vessel rests on a course of fireclay bricks, and the far end is closed with them.

5. Raise the vessel. Right-click the boiler block with each stage's materials in your hotbar. The base appears when the block is placed; three stages follow.

   stage	materials
   base extension	6 iron or steel plates, 4 nails and strips, 8 fireclay bricks
   flues	8 iron or steel plates, 4 iron or steel rods, 4 nails and strips
   casing	8 iron or steel plates, 8 nails and strips, 4 iron or steel rods, 36 fireclay bricks

   The fireclay bricks here are the item, not the wall blocks of the firebox.

6. Take the steam off the top. The steam connector is the cell on top of the vessel two along from the boiler block; the pipe goes in the cell directly above it. Everything else on top is solid.

The reserved cells around the vessel are not blocks you place. The construction claims them itself and they hold the collision of the finished machine.

The three sides

Feedwater enters underneath, through that bend passthrough. The boiler draws from it on its own, up to 10 L/s, and stops at half its capacity so there is always room for steam.

Steam leaves the top connector, and nothing else. Until a pipe sits above that cell the neck is open and the boiler simply bleeds steam into the air.

Exhaust leaves the far end. It must be able to go somewhere: a chimney on the outlet draws exactly what the fire makes, and an open pipe end does not.

First firing

1. Open the lid: hold right-click on the top of the vessel, one cell along from the boiler block. It is a hold, not a click.
2. Pour in water, one container at a time. A stack of buckets loses everything but one bucketful. The boiler needs 150 L before it will do anything.
3. Close the lid.
4. Lay a coal pile in the firebox slot behind the door and light it.
5. Wait. The look-at line counts up through "Heating up", and the first steam comes about three minutes after lighting.
6. Watch the outlet pressure climb on the steam line and not on the boiler. The vessel and the run equalise, so a long line takes longer to come up.

When it goes wrong

It says the structure is incomplete and everything looks built. Show the outline. The usual culprits are the cell under the outlet, which has to be air, a snow layer, and a passthrough turned the wrong way.

Nothing happens after lighting the coal. Either the water is below 150 L or the exhaust has nowhere to go. A choked boiler says so on the look-at line and snuffs its own fuel pile after 10 seconds.

The wrench will not finish the build. Electrical Progressives' Advanced Wrench fails silently on these multiblocks. Use the vanilla one.

Steam but no pressure. An open end somewhere on the steam run bleeds 8 L/s. Turn on the network highlight and walk the line.

It exploded. See Boilers: a Cornish sitting at 5 atm, still firing, with the lid shut, for 30 seconds is the one case that does it.