The flame or whatever it was had enough heat, but it was hard to control.
( ( ( ( ( ( ( ( The flame ) or ) whatever ) ( it ( was ( had ( enough heat ) ) ) ) ) , ) but ) ( it ( was ( hard ( to control ) ) ) ) ) . )
(ROOT (S (S (NP (NP (DT The) (NN flame)) (CC or) (NP (NNP whatever))) (NP (PRP it)) (VP (VBD was) (VP (VBN had) (NP (JJ enough) (NN heat))))) (, ,) (CC but) (S (NP (PRP it)) (VP (VBD was) (ADJP (JJ hard) (S (VP (TO to) (VP (VB control))))))) (. .)))
The flame was hard to control, but had enough heat. 
( ( The flame ) ( ( ( ( ( was ( hard ( to control ) ) ) , ) but ) ( had ( enough heat ) ) ) . ) )
(ROOT (S (NP (DT The) (NN flame)) (VP (VP (VBD was) (ADJP (JJ hard) (S (VP (TO to) (VP (VB control)))))) (, ,) (CC but) (VP (VBD had) (NP (JJ enough) (NN heat)))) (. .)))