Energy Savings >> Linkageless Burner Upgrades

TEC specializes in retrofitting existing burners with linkageless combustion controls in order to optimize combustion efficiency. This typically results in savings in the 3% to 10% range. Sometimes greater savings can be achieved, but these are dependent on a number of factors. (See our FAQ for more details.)

In perfect combustion, fuel and air would be mixed at a ratio that would result in 0% excess oxygen in the flue (exhaust) gasses. 100% combustion is not possible, but by reducing the excess oxygen to the lowest possible percentage while still keeping CO (carbon monoxide) levels at a safe threshold, significant savings can be achieved. 20% of air is comprised of oxygen, therefore reducing excess oxygen from 6% to 3% would lower the excess air found in the combustion gasses from 30% to 15%. Air requires energy to heat it and that energy is better spent heating your living or working space than heating the environment—via your chimney.

Most burners in operation employ one servo motor to drive the various fuel valves and air shutters (a non-linkageless system).

These valves and air shutters are interconnected through a series of shafts and linkages and thus move in relationship to one another to achieve the correct mixture of fuel and air. The problem with having only one servo motor regulating the air and fuel input is that it is hard to achieve the exact fuel-air ratio at various points along the firing range.

For example, let’s say the highest combustion efficiency achievable from a specific boiler is 84.6%. With a non-linkageless set up, the burner could be adjusted to achieve peak efficiency at 10% of firing rate (low fire) and 100% of firing rate (high fire). However at any other point along the combustion curve peak efficiency would be very difficult to achieve.

Consistent fuel efficiency along the firing range, which is improbable with a single fuel burner, is impossible with a multi-fuel burner on a non-linkageless system. With multi-fuel (gas-oil) burners one of the fuel’s combustion efficiencies will be compromised, since the air shutter opens to the same degree irrespective of the fuel being burned.

Linkageless combustion controls maximize combustion efficiency as each fuel valve and air shutter are regulated by an independent servo motor and the air shutter servo motor is programmed to open at different rates for different fuels. There are real advantages to having fuel and air inputs being regulated by separate servo motors.

The independent servos are controlled by a micro-processor that is programmed to achieve peak combustion efficiency along a combustion curve that can have as many as 24 points.

Some systems such as Honeywell’s Control Links are relatively inexpensive and perform only fuel-air ratio control. They require an external PID load controller and flame safe guard (see installations). The control may have an internal load controller and flame safe guard incorporated into the processor and have additional features such as checking the fuel valves’ integrity (valve proving).

Siemens LMV 51 and 52 controls are an example of full-featured controls (see installations).

Apart from load control, there are systems that can do a variety of ancillary functions such as lead/lag, outdoor reset and even water feed. Autoflame’s line of combustion management controls offers complete boiler management.

Each system has its advantages and disadvantages. TEC can service and install any of the leading systems.

Additional savings can be achieved by incorporating oxygen trim into the combustion control. Oxygen trim will automatically trim air and/or fuel inputs by sampling combustion gasses (you can read more about oxygen trim in our ancillary section).