What happens to the furnace pressure when the cracking heater is shut down?
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Everyone, I have a question that needs answering: if a heating furnace stops operating suddenly, how will the pressure inside the furnace change? Why does the signal of low blower pressure appear? If the outlet pressure is very low, does that mean that the negative pressure in the furnace increases after the heating furnace stops operating suddenly? Could you explain it in more detail? Thank you!
What exactly does stopping the furnace include? A low outlet pressure of the blower may indicate a problem with the blower, which is why the outlet pressure is low.
The furnace suddenly went out, and the pressure of the blower was low, indicating that the pressure inside the furnace was low at that moment, which caused the fire to be extinguished. It is necessary to analyze why the furnace pressure is low.
This post was last edited by Gangda Dadi on 2015-11-2 08:18. If both the main burner and the pilot light of the heating furnace are extinguished, and if the blower stops operating, then the furnace chamber will gradually reach normal pressure and remain at that pressure thereafter； If the blower is operating, the furnace chamber will gradually move toward normal pressure and then to positive pressure. That is, after the heating furnace is shut down, the negative pressure in the furnace chamber disappears and it becomes at normal pressure or positive pressure. The low outlet pressure of your fan is due to the disappearance of negative pressure in the furnace, which results in low inlet pressure for the fan; that’s why the outlet pressure is also low. (Heating furnace without induced draft fan)
The blowers and exhaust fans are operating normally; the heating furnace went out mainly because the fuel gas, fuel oil, and pilot light were all cut off. I mainly want to know the trend in the air pressure inside the furnace after the flame goes out due to the interruption of the fuel gas supply to the furnace.
There is no problem with either the blower or the exhaust fan; it is suspected that a malfunction in the interlock system caused the furnace to stop operating. What I mainly want to know is: the change in furnace pressure after the flame goes out due to a sudden cut-off of the fuel gas. The first phenomenon that occurs is an increasing oxygen content; however, since the furnace is originally under negative pressure, how will the pressure change?
I guess the negative pressure in the furnace will increase. Here are my conclusions: Assuming the fuel gas is methane and it burns completely, the total amount of (CO2 + H2O) produced as a result of the reaction between methane and the oxygen in the air is equal to the total amount of (CH4 + O2) consumed. When the fuel gas is cut off, no more CO2 and H2O are produced ； With the damper positions of the blower and exhaust fan remaining unchanged, since the volume of gas entering is less than before, the negative pressure in the furnace increases, that is, its absolute value rises