"80% efficient" gas furnace design and sequencing
If the appliance has a galvanized pipe coming out of the top of the appliance it is considered 80% efficient if it was built within the last 25 years.
These appliances still use the heat from the exhaust gasses to remove them from the structure.
They use inducers to help remove the burnt gasses.
Most of the controls for these furnaces are similar to 90% efficient appliances.
These appliances still use the heat from the exhaust gasses to remove them from the structure.
They use inducers to help remove the burnt gasses.
Most of the controls for these furnaces are similar to 90% efficient appliances.
Parts of an 80% efficient furnace
The vent gasses leave the appliance through the silver pipe at the top of the appliance.
The inducer is located below the vent pipe.
A pressure switch is located to the left and above the inducer.
Gas supply comes in from the left and ends at the gas valve.
The black pipe on the right of the gas valve is called the manifold. It distributes the gas to small diameter brass orifices which feed the gas to the burners. The burners in this appliance are called inshot burners because they shoot gas into the burners and draw air with the gas to mix air and gas to prepare it to burn.
The gas burns, liberating heat which conducts through the heat exchanger wall. A circulating fan is located below the heat exchanger to pass air over the heat exchanger to pick up the heat and distribute it throughout the structure. Next
The inducer is located below the vent pipe.
A pressure switch is located to the left and above the inducer.
Gas supply comes in from the left and ends at the gas valve.
The black pipe on the right of the gas valve is called the manifold. It distributes the gas to small diameter brass orifices which feed the gas to the burners. The burners in this appliance are called inshot burners because they shoot gas into the burners and draw air with the gas to mix air and gas to prepare it to burn.
The gas burns, liberating heat which conducts through the heat exchanger wall. A circulating fan is located below the heat exchanger to pass air over the heat exchanger to pick up the heat and distribute it throughout the structure. Next
