Hydronic Heating

Related terms

• Junction Box

  An enclosure where wires connect; all splices must be in an accessible box, never buried in a wall. A common code violation in DIY work.

• Humidifier (Whole-House)

  A unit added to the furnace adding moisture in winter for comfort and to protect woodwork and floors.

• Knob-and-Tube Wiring

  Obsolete early-1900s wiring with no ground. Often must be replaced during remodels and can affect insurance and insulation.

• HSPF2

  The current heating-season efficiency rating for heat pumps (replaced HSPF in 2023). Higher means more heat per unit of electricity.

• Line Set

  The insulated copper tubing connecting the outdoor condenser to the indoor coil. Replaced or flushed when changing refrigerant type.

• Hose Bib / Sillcock

  An exterior faucet; frost-free types extend the valve inside the wall to prevent freeze-burst. A common winter failure point.

• Load Calculation (Electrical)

  An NEC calculation of total demand to verify the service/panel can carry added loads. The basis for whether a service upgrade is required.

• Heat-Pump Water Heater

  A hybrid tank that pulls heat from surrounding air — 2–3x more efficient than electric resistance. Needs space and produces cool exhaust…