jelca -jel- gismu

x1 burns/[ignites/is flammable/inflammable] at temperature x2 in atmosphere x3.

Default x2/x3 to normal temperatures in air; ignite (= jelcfa), flammable/inflammable (usually = jelka'e or jelfrili). See also fagri, kijno, sigja, livla, sacki.

In notes:

fagri
x1 is a fire/flame in fuel x2 burning-in/reacting-with oxidizer x3 (default air/oxygen).
kijno
x1 is a quantity of/contains/is made of oxygen (O); [metaphor: supporting life/combustion].
livla
x1 is a fuel/energy-source for powering x2.
sacki
x1 is a match [incendiary device] made of x2.
sigja
x1 is a cigar/cigarette/cigarillo made from tobacco/smokable substance x2 by x3.
jelbo'i
x1 is a molotov's cocktail/bottle bomb containing x2
jelka'e
x1 is flammable / inflammable under conditions x2
jelnanba
n1=j1 is toasted bread made from grain(s) n2.
mudyfagri
f1 is a wood fire burning in/reacting with oxidizer f3.