Chapter 5.2.2 - Electrical Principles

The physical laws of electricity and related calculations will assist the designer in
relating the equipment alternatives to the available energy resources, circuits
required, and performance validation. Electricity is the movement of electrons, the
negatively charged particles of atoms, through a conductor (e.g., wire) and known as
current. Materials that impede electron or current flow are known as insulators, or
dielectric materials (e.g., plastic, glass, and wood). A conductor or series of conductors
is known as a circuit.

A circuit consists of a voltage source that utilizes a conductor to allow the flow of
current to the load.The current flow is measured in amperes, or amps.The capacity
of a conductor to carry current is called its ampacity. The force that causes electrons
to move through the conductors is called the electromotive force, or EMF, of the circuit.
This is also known as the potential difference, or the imbalance in a circuit that
causes current flow. This is shown in a wiring diagram by labeling one side of the
power source as positive and the other side as negative. Current flows from the negative
to the positive and is generally referred to as amps and volts.

Thinking about electricity as water flowing through a pex tube is a good way to
understand the difference between amperage and voltage.Water in the tube is like
current in the circuit, measured not in gallons per minute, but in amperage. Both can
be measured in volume and do work. However, the water must move due to water
pressure from a pump or gravity to do work, normally transfer heat from the boiler to
the radiant panel.With electricity you need both volts and amps to run the heater.The
pex tubing used in radiant hydronic systems is like the conductor in the electric circuit.