▁chim ney ▁rather ▁than ▁into ▁the ▁room ▁( which ▁reduces ▁efficiency ). ▁The ▁biggest ▁problem ▁with ▁leaving ▁the ▁air ▁controls ▁fully ▁open ▁on ▁many ▁st ov es ▁is ▁“ over f iring ”. ▁Over f iring ▁is ▁caused ▁when ▁too ▁much ▁heat ▁is ▁generated ▁within ▁the ▁fire ▁chamber , ▁which ▁will ▁lead ▁to ▁war ping , ▁bu ck ling ▁and ▁general ▁damage ▁to ▁the ▁st ove ▁and ▁its ▁internal ▁components . ▁D ifferent ▁st ov es ▁have ▁different ▁numbers ▁and ▁types ▁of ▁air ▁controls . ▁ ▁Modern ▁building ▁techniques ▁have ▁created ▁more ▁a irt ight ▁homes , ▁forcing ▁many ▁st ove ▁manufact ur ers ▁to ▁design ▁their ▁st ov es ▁to ▁permit ▁outside ▁air ▁int akes . ▁Out side ▁air ▁can ▁improve ▁the ▁overall ▁efficiency ▁of ▁the ▁st ove ▁as ▁a ▁he ater ▁by ▁drawing ▁cold ▁comb ust ion ▁air ▁directly ▁from ▁the ▁outside ▁instead ▁of ▁drawing ▁pre he ated ▁air ▁from ▁the ▁room ▁that ▁the ▁st ove ▁is ▁in . ▁Many ▁modern ▁st ov es ▁can ▁option ally ▁use ▁an ▁outside ▁air ▁int ake . ▁Many ▁manufact ur ers ▁supply ▁the ▁necessary ▁parts ▁in ▁k it ▁form ▁( an ▁Out side ▁Air ▁Kit , ▁or ▁O AK ). ▁When ▁considering ▁an ▁outside ▁air ▁k it , ▁it ▁is ▁important ▁to ▁know ▁that ▁the ▁air ▁must ▁come ▁in ▁from ▁below ▁the ▁level ▁of ▁the ▁st ove . ▁For ▁example , ▁a ▁bas ement ▁st ove ▁may ▁not ▁safely ▁use ▁an ▁outside ▁air ▁k it . ▁This ▁is ▁to ▁prevent ▁a ▁revers al ▁of