The Importance of Modulation

In general, modulation refers to the ability to adjust a boiler's or water heater's firing rate (input) to meet the heating demand (output) of the system.

AERCO equipment utilizes a fully modulating design that precisely matches firing rate to actual building demand. A 2.0 million BTU/hr. capacity Benchmark boiler can run with as little as 100,000 BTU/hr., or 5%, input. Likewise, the 1.0 million BTU/hr. KC1000 line maintains steady combustion with only 50,000 BTU/hr. input. Drawing only enough fuel to meet actual load changes, each unit will gradually increase its capacity – in precise 1% increments – up to 100% capacity.

Not only is less fuel burned as a result of modulating input, but also heat transfer is enhanced when the AERCO units operate at "part load." Constant operation maintains temperatures within the heat exchanger, yet the reduced input increases the time these combustion gases are in contact with the heat exchanger surface, promoting greater energy transfer and cooler exhaust gases. AERCO equipment features an inverse efficiency curve performing best at lowest loads.

Since the majority of a boiler's operating hours will be under "part load conditions," modulating units promise greater seasonal efficiency.

BMS and Modulation

AERCO's inverse efficiency profile can be fully leveraged by carefully coordinating the operation of multiple units by using the AERCO Boiler Management System. Put simply, it requires less energy for a group of modulating boilers, each firing at a lower load, to heat a building than for a single boiler operated at full or high fire to carry the entire workload.

AERCO's BMS regulates the operation of multiple Benchmark or KC1000 installations, giving each unit firing instructions to maximize the efficiency of the plant as a whole as loads change throughout the day. Operating hours are also distributed evenly across all units, always alternating the lead boiler so that no particular unit receives more work over time than the others do.