Three-Way / Multi-Way Switch

Related terms

• Tonnage

  AC/heat-pump cooling capacity (1 ton = 12,000 BTU/hr). Sized by a load calculation, not square footage rules of thumb — oversizing hurts…

• Thermostat

  The control that calls for heating/cooling. Programmable and smart models cut energy by matching conditioning to occupancy.

• Two-Stage / Modulating

  Equipment that runs at partial capacity most of the time for efficiency and comfort, ramping up only on extreme days.

• Tankless Water Heater

  An on-demand heater with endless hot water and no standby loss. Higher install cost; gas units often need larger gas/vent lines.

• UEF (Uniform Energy Factor)

  The standardized water-heater efficiency metric for comparing models; higher UEF means less energy per gallon delivered.

• Tank Water Heater

  A storage water heater keeping a tank hot. Lowest upfront cost; standby losses and limited capacity are the trade-offs.

• Variable-Speed Blower

  An ECM blower that ramps output to match demand for steadier temperatures, better humidity control, and lower electricity use than single…

• Tamper-Resistant Receptacle

  An outlet with internal shutters preventing object insertion, code-required in dwelling living spaces.