Oxyhydrogen will combust when brought to its autoignition temperature.  For the stoichiometric mixture in air, at normal atmospheric pressure, autoignition occurs at about 570 °C (1065 °F).  The minimum energy required to ignite such a mixture, at lower temperatures, with a spark is about 20 microjoules.  At standard temperature and pressure, oxyhydrogen can burn when it is between about 4% and 95% hydrogen by volume.
When ignited, the gas mixture converts to water vapor and  releases energy, which sustains the reaction: 241.8 kJ of energy (LHV) for every mole of  burned.  The amount of heat energy released is independent of the mode of combustion, but the temperature of the flame varies.  The maximum temperature of about  is achieved with an exact stoichiometric mixture, about  hotter than a hydrogen flame in air.
When either of the gases are mixed in excess of this ratio, or when mixed with an inert gas like nitrogen, the heat must spread throughout a greater quantity of matter and the flame temperature will be lower.