Firepit

Size	N/A
Where	Outside

Warning: USING firepits cause Pollution

A firepit allows for the safe burning of wood with the help of flint and tinder to start the fire. The residue of a firepit is charcoal. Fish and vegetables can be grilled over the fire. Additionally, some items can be burned in a firepit to produce ash or lime.

Source

This building becomes available once you have learned the Controlled Burn tech. The Firebuilding skill is also required to light it.

Cost

• 40 Firebricks
• 80 Slate

Built Outside (Self > Projects > Charcoal).

Use

• Produce Charcoal from 200 Wood.
• Add up to 20 of each type of Fish and Vegetables, except Leeks, to grill them. You will need a Sharpened Stick for each type of food being grilled.
• Add up to 100 Leeks, 100 Dried Flax, and/or 100 Dried Papyrus to produce Ash.
• Add up to 100 Limestone to produce Lime.

Starting the fire

You need 1 Flint, and at least 1 Tinder to start the fire.

Each attempt to light a fire can:

• Succeed;
• Fail - you can try again immediately;
• Fail and consume the Tinder - you will need to add more before trying again.

You will sometimes gain skill in Firebuilding by attempting to light a fire.

Stoking the fire

Once a fire has been lit, you have the option of stoking it if you have a Sharpened Stick or an Iron Poker. If you have both, it will let you choose which to use. Both seem to act identically other than that the poker does not seem to have a chance to burn up. Stoking a fire correctly keeps it burning longer, which increases its charcoal, ash, and lime yields. Stoking does not affect grilled food yields.

A firepit runs through the following stages:

• A very dim warmup stage, immediately after lighting. Stoking the fire at this stage will put the fire out immediately and you will recover all materials except Tinder unburned.
• Burning merrily: a normal stage where the fire is orange. Stoking the fire at this stage will put it out, but not immediately - it will go to the "smouldering out" stage first. This phase can last for anywhere from 10 to 45+ seconds.
• Periodically, the fire will brighten then dim (orange -> yellow -> white -> yellow -> orange) over a period of 14-15 seconds. You must stoke the fire exactly once during each of these phases. If you correctly stoke the fire, it will continue burning and return to the previous "normal" stage at the end of this stage. If you do not stoke the fire in time, it will become "smouldering out".

If you look at the center of the fire with a color picking program it is trivial to know when a stoke phase occurs. The Hue of a fire will be 60 during the no-stoke phase, and then the Hue will drop to 0 for the stoke phase.

• Smouldering out: The fire has gone out and the firepit is cooling. This stage takes approximately 5 minutes. You will get a message in Main ("Your firepit has smouldered out") when the fire finishes cooling. At this point, the final products are produced and can be taken from the firepit.

It is possible to leave the byproducts of firepit usage (charcoal, lime, ash) inside the firepit and still use it.

Other Tips

• When you first start, it is imporant not to panic-- the flames are going to seem to fluctuate between the stages. What you are looking for are the times when it holds the color-- long stretches of orange-- a solid few seconds of yellow-- the blinding white and so on.

• Wait for the Orange. You do your thing after orange-- and after staring at orange for so long-- the change to yellow/white is an obvious one and you can stoke.

• For record purposes, it helps to type the stoke number into main-- so you can keep track of how many stokes you've done-- and the approximate time spent.

Yield

The yield of a firepit depends on:

• The number of ingredients originally added.
• For lime, ash, and charcoal: the time (not number of stokes!) the firepit burned for.

Optimal load

The yield formula appears to involve some integer truncation. This means that you do not have to fully load the firepit to get maximum yield! The optimal loads for each resource are:

• n*16 Limestone (16, 32, 48, 64, 80, 96)
• n*40 Leeks (40, 80)
• n*20 Dried Flax (20, 40, 60, 80, 100)
• n*20 Dried Papyrus (20, 40, 60, 80, 100)

For example, if you have 20 limestone, add 16 to the firepit and keep the other 4. Adding 20 limestone will yield the same as adding 16. If you put less than 16 limestone in, you won't produce any lime.

This also means that you shouldn't fully load a firepit with maximum amounts of everything. Only load 96 limestone and 80 leeks, not 100 of each, and you will still get the same yield.

Sample yields

This table shows yields for a full firepit and stoking times up to 60 minutes. Note that the actual burn time will be approximately 6 minutes longer due to warmup/cooldown periods.

stoking time (teppyminutes)	charcoal	lime from 96 limestone	ash from 100 dried flax	ash from 80 leeks	ash from 100 dried papyrus
0	25	13	11	4	17
5	30	16	14	5	23
10	34	19	15	6	28
15	38	20	17	6	32
20	41	22	18	7	36
25	43	23	19	7	39
30	45	24	20	8	42
45	51	28	23	9	50
60	56	30	25	10	57

Vegetables and fish always yield 1 grilled food for every 1 ingredient, regardless of stoking time.

Yield Formula

These formulas match the test data (see the discussion page) very well, and were used to generate the above table.

 t = int( (burning duration in teppyseconds) / 30 )
 charcoal = int( t^(1/3) * 11 )
 lime from limestone = int( t^(1/3) * int(limestone/16) )
 ash from flax = int( t^(1/3) * int(flax/20) )
 ash from leeks = int( t^(1/3) * int(leeks/40) )
 ash from papy = int( t^(1/2) * int(papy/20) )

As a note, I haven't quite figured out how to use the firepit correctly and I often stoke it at the wrong time, making the fire go out prematurely. Often this yields low amounts of ash, lime and charcoal, but recently something strange happened: I had three fires going, two loaded with 96 dried flax and 100 limestone, one with just 96 dried flax. The first went out prematurely after a few minutes only with 7 ash (IIRC), the second shortly thereafter with, I think, even lower yields. However, the last one lasted maybe 10-20 seconds longer before it ended prematurely and yielded 24 ash (26 lime and 48 cc)! It had then run for about 3-5 minutes, which shouldn't yield such amounts according to the above figures. -- Tumaini

Are you sure you didn't load the 3rd one with papyrus, not flax? 24 ash sounds about right for 100 papy for 5 mins --Inkoaten 18:28, 19 March 2009 (EST)

Yes, I'm absolutely sure, since I don't have a single papyrus at the moment. -- Tumaini