An ohm (Ω) is the unit of electrical resistance that measures how much a component opposes the flow of electrical current through a circuit. Resistance is fundamental to understanding electrical behavior in HVAC control circuits and solar systems. Higher resistance increases power loss as heat.
Technical Details
One ohm is defined using Ohm’s Law: V = I × R, where 1 ohm represents the resistance of a conductor that allows 1 ampere to flow when 1 volt is applied. Resistance is measured using an ohmmeter. Common HVAC components have specific resistance values: thermostat heating elements, compressor windings, and motor coils all have measurable ohmic values. Resistance changes with temperature, wire gauge, and material composition.
HVAC Diagnostics
Technicians measure resistance in compressor windings to detect electrical faults. A shorted winding shows near-zero ohms, while an open circuit shows infinite resistance (OL on meters). Motor windings typically measure between 2 and 20 ohms depending on motor type and size.
System Efficiency Impact
Higher resistance in electrical connections increases energy losses and heat generation. Loose connections develop additional resistance over time. Maintaining low-resistance connections improves HVAC efficiency and component lifespan.