My heater will ignite when I first turn on the Heater for the jacuzzi and the burners will stay lit until the water reaches the set temperature. When the water comes down in temperature it will try to reignite and the burners will not light. Meanwhile the gas is building up and when it tries to ignite flames come out of the top and the burners still don't burn. Of course I turned the heater off. Can anyone help me out with a possible diagnoses. Thank you