Today's condensing boilers are much different than their predecessors. Condensing boilers feature efficiencies over 90% with Triangle Tube's Prestige and Challenger boilers reaching AFUEs of 96% and 95% respectively. Much of these efficiency gains come from much 
better control of the combustion process.
High efficiency boilers use a sealed combustion process where a fan brings air and fuel (natural gas or propane) into the burner. In most cases this air is brought into the boiler from the outside. This avoids the creation of a negative pressure zone in the house and also avoids sending heated air out the flue pipe. A gas valve senses the air pressure from the fan and allows a precisely metered amount of gas into the burner.
The fan speed will determine how much gas is consumed and how much heat is produced. The boiler's control will determine how fast the fan should go based on the heating load. When the heating load is low, the fan will slow down, drawing less gas, and producing less heat. This provides two benefits. First, the combustion process is more efficient when it is burning at "low fire" than it is at "high fire". So the more time the boiler operates at lower firing rates the more fuel efficient it is. Second, this minimizes the cycling of the boiler from "on" to "off". Cycling both reduces the fuel efficiency and increases the wear on the hydronic heating system.
The gas-air mixture is burned on a burner head. The Prestige burner head is shown here. The flame is controlled on the burner head to maximize the efficiency, which minimizes emissions. These burner heads are highly engineered to hold the flame properly throughout the range of firing rates. The flame is lit by the ignitor, which is the orange rod shown in the picture. Unlike the standing pilots used in boilers in the past, today's high efficiency boilers use electronic ignition, eliminating the waste from burning the standing pilot.
This process is much more precise than the traditional atmospheric burners in older boilers. Triangle Tube has designed boiler combustion processes to maximize the efficiency of their boilers. As technology evolves, tomorrow's boilers will continue improve their efficiency.
better control of the combustion process.High efficiency boilers use a sealed combustion process where a fan brings air and fuel (natural gas or propane) into the burner. In most cases this air is brought into the boiler from the outside. This avoids the creation of a negative pressure zone in the house and also avoids sending heated air out the flue pipe. A gas valve senses the air pressure from the fan and allows a precisely metered amount of gas into the burner.
The fan speed will determine how much gas is consumed and how much heat is produced. The boiler's control will determine how fast the fan should go based on the heating load. When the heating load is low, the fan will slow down, drawing less gas, and producing less heat. This provides two benefits. First, the combustion process is more efficient when it is burning at "low fire" than it is at "high fire". So the more time the boiler operates at lower firing rates the more fuel efficient it is. Second, this minimizes the cycling of the boiler from "on" to "off". Cycling both reduces the fuel efficiency and increases the wear on the hydronic heating system.
The gas-air mixture is burned on a burner head. The Prestige burner head is shown here. The flame is controlled on the burner head to maximize the efficiency, which minimizes emissions. These burner heads are highly engineered to hold the flame properly throughout the range of firing rates. The flame is lit by the ignitor, which is the orange rod shown in the picture. Unlike the standing pilots used in boilers in the past, today's high efficiency boilers use electronic ignition, eliminating the waste from burning the standing pilot.
This process is much more precise than the traditional atmospheric burners in older boilers. Triangle Tube has designed boiler combustion processes to maximize the efficiency of their boilers. As technology evolves, tomorrow's boilers will continue improve their efficiency.
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