HVACR116 – Trade Skills Plumbing, HVAC, Electrical Overview

Plumbing, Heating, and Air Conditioning

Objectives After completing this unit, you will be able to perform the following tasks: o Explain the basic principles of plumbing design o Identify the plumbing symbols used on drawings

Introduction Residences have a plumbing system consisting of a water supply system; a water distribution system; and a drain, waste, and vent system (DWV) o Water supply system provides a source of water o Water distribution system provides hot and/or cold water o Drain, waste, and vent system disposes water after use

Plumbing Materials Copper resists corrosion, but is expensive Plastic is light, noncorrosive, and easily joined o Must have a temperature rating of 180°F o Not suitable for some applications Cast iron is strong and resists corrosion o Used where DWV piping passes through the foundation and outside the building Black iron is used almost exclusively for gas piping

Fittings Couplings: join two pipes in a straight line Union: allows disconnection without cutting Elbows: change piping direction Tess and wyes: have three connections to allow a second pipe to join the first from the side Cleanouts: provide access to sewage for cleaning Valves: stop, start, or regulate water flow

Figure 35–1. A coupling is used to permanently join lengths of pipe. Figure 35–2. A union allows the piping to be disconnected easily. Figure 35–3. Street 90° elbow and 45° elbow. Figure 35–4. Sanitary tee and wye. Figure 35–5. A cleanout allows access to the system.

Design of Supply Plumbing In most communities, water is distributed through a system of water mains under or near the street o When a new house is constructed, municipal water department taps this main o A water meter is installed where water enters the house and measures water used o Cold-water and hot-water distribution piping runs through the house

Figure 35–6. Hot- and cold-water piping.

Drainage Waste and Vent System Main purpose of a drainage system is to remove wastewater and solids from a building o A drain is installed at each fixture o All individual drains are connected to create a building drain, which connects to the sewer  Sewer conveys wastewater and solids to a municipal sewer, septic tank, or other point of disposal

Drainage Waste and Vent System (cont’d.) Vents allow air circulation to equalize positive and negative piping pressures Traps are fittings that fill with water to prevent sewer gas from entering the building o As water rushes through a trap, it is possible for a siphoning action start  Vent openings allow air pressure to enter the system and break trap suction

Figure 35–7. Water hammer arrester. Figure 35–8. A trap fills with water to prevent sewer gas from entering the building. Figure 35–10. Venting a trap allows air to enter the system and prevents siphoning. Drainage Waste and Vent System (cont’d.)

Figure 35–11. DWV system.

Plumbing Plans Floor plans show all plumbing fixtures by standard symbols Fixture dimensions are provided by manufacturers on rough-in sheets For simple plumbing, plumbers prepare estimates and bids For complex plumbing, plumbing contractors draw a plumbing isometric

Heating, Ventilating, and Air Conditioning Plans for residential construction do not usually include sheets for HVAC (heating, ventilating, and air conditioning) o Floor plans include basic information  Location of furnace, air-handling unit, or air-conditioning unit  Diffuser and air return locations

Figure 35–15. The air cycle in a forced-air system.

Electrical

Objectives After completing this unit, you will be able to perform the following tasks: o Identify the electrical symbols shown on a plan o Explain how the lighting circuits are to be controlled

Current, Voltage, Resistance, and Watts To do work, electrical energy must have movement o Current is movement  Measured in amperes o Voltage is the force behind an electric current o Resistance is the ease or difficulty with which the current flows  As resistance goes up, current flow goes down

Current, Voltage, Resistance, and Watts (cont’d.) Amount of work electricity can do depends on current amount and current force o Electrical work is measured in watts  Watts is found by multiplying amperes by volts Figure 36–1. Current, voltage, and power ratings of some typical electrical devices.

Circuits For current to flow, it must have a continuous path from power source, through electrical device, and back to its source (i.e., a circuit) Figure 36–2. A complete circuit includes a path from the supply to the device and back again.

Circuits (cont’d.) A switch allows the continuous path to be broken Using two 3-way switches, the circuit can be controlled from two places Material carrying electric current is a conductor o When two or more wire conductors are bundled together, they make a cable

Figure 36–3. A switch is used to break (or open) the circuit. Figure 36–4. Three-way switches allow a device to be controlled from two locations. Notice that if either switch is activated, the device will be energized. Figure 36–5. This cable has two circuit conductors and one ground conductor. Courtesy of Anaconda Wire and Cable Division.

Circuits (cont’d.) Conduits are made by pulling individual wires through steel or plastic pipes o Used in larger buildings In houses, cables containing wires plus one ground conductor are common o Ground does not carry current and protects from shock

Circuits (cont’d.) o Ground-fault circuit interrupter measures current flow in hot and neutral conductor If a faulty device allows current to flow through a person, GFCI stops all current flow immediately  National Electric Code® requires their use on circuits for outlets installed outdoors, in kitchens, bathrooms, garages, and near water hazards

Circuits (cont’d.) Service feeder cable ends at a distribution panel o From the distribution panel, electrical system splits into several branch circuits  Each branch includes a circuit breaker or fuse o Circuit breaker or fuse opens the circuit if current flow exceeds rated circuit capacity

Figure 36–6. The electrical service is split up into branch circuits at the distribution panel.

Circuits (cont’d.) National Electrical Code® specifies the design of safe electrical system o Items include:  Kinds and sizes of conductors  Locations of outlets and devices  Overcurrent protection  Number of conductors allowed in a box  Safe construction of devices  Grounding  Switches

Electrical Systems on Plans Residential construction drawings include electrical information on floor plans o Only symbols for outlets, light fixtures, switches, and switch wiring are included o Exact location may not be included o Wiring is left to electrician’s judgment and electrical code regulations

Electrical Systems on Plans (cont’d.) Switch wiring for light fixtures show which switch controls each light fixture Figure 36–7. Switch legs on a plan.

Electrical Systems on Plans (cont’d.) In split wiring, one-half of the outlet is always hot; the other half can be opened by a switch Figure 36–8. Split-wired outlet.