Comparing Single-Stage and Two-Stage Heating

October 28, 2013
Ross and Witmer

Comparing single-stage and two-stage heating is easy when you realize that a single-stage furnace offers only two heat outputs: zero percent and 100 percent. Anything in-between isn’t possible with a single-stage burner. While many homeowners might not see anything wrong with full-blast operation, especially on the coldest day of the year, at most other times during the winter your home doesn’t require 100 percent heating output. It wastes energy and doesn’t generate consistent temperatures in living spaces.

Two-stage heating provides a secondary heat output of approximately 65 percent. When temperature conditions warrant, the system automatically stays at the lower output setting.

For comparing single-stage and two-stage heating, here are some the advantages of a lower heating output:

  • Energy efficiency – A single-stage furnace is at 100-percent output whenever it’s on. By comparison, a new two-stage heater operates at 100-percent output less than 25 percent of the time. This means that 75 percent of the winter it’s consuming about 35 percent less energy than the single-stage unit.
  • Increased comfort – One of the telltale differences between one-stage and two-stage furnace operation are abrupt temperature swings. Temperatures in living spaces may vary up to 10 degrees above or below the thermostat setting as the unit cycles on and off repeatedly at full output. In lower output mode most of the time, a two-stage furnace runs longer and heats more consistently. This typically results in fluctuations of less than two degrees above or below the thermostat’s target temperature.
  • Less wear and tear – Furnace components last longer when they’re gradually heated and run longer heating cycles. Single-stage and two-stage furnace comparisons show that lower output produces longer expected service life and fewer maintenance and repair issues. Rapid heating followed by quick cooling in full-blast operation causes expansion and contraction that prematurely ages parts of the furnace, particularly the expensive heat exchanger. Two-stage furnaces start in the lower output mode, heat gradually and run extended “on” cycles.

For more advice about comparing single-stage and two-stage heating in the Gaston area, contact Ross & Witmer today.

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