NATE CORE QUESTIONS WITH CORRECT ANSWERS RATED A+

Why would you want to introduce fresh air into an occupied residential structure? - To create a neutral pressure within building. A ducted distribution system that is not in the conditioned space and is well sealed on the supply side but has numerous leaks on the return side can create? - A positive pressure within the conditioned space. What are some of the drivers that can create a negative pressure within a building? - The duct system, A central vacuum systems, chimneys and exhaust fan. For combustion to occur what three elements are necessary ? - Oxygen, fuel and heat. The process for combustion - A chemical reaction. Why are humidifiers commonly used along with furnaces and heat pumps during the heating season? - To improve comfort within the occupied space by increasing the moisture content of the air. Which has the greater capability to hold moisture? - Hot air. The greater the difference in temperature between wet bulb and dry bulb - The lower the %RH A dry bulb temperature? - Can be off of a common thermometer and is the standard by which most customers rate the heating and cooling systems in their homes. What are the basic essentials of human comfort? - Temperature, relative humidity and air velocity. A joist is - A horizontal structure member. A stud is - A vertical structure member. A stud is - Attaches to the top plate and to the sole plate and is typically placed on 16'' centers in residential. The material that covers the weather side of the rafters is - Sheathing. A pier and beam foundation would be used for - A house built over a crawl space. A differential pressure gage can - Read differential pressure and read a pressure relative to the atmosphere. The tool necessary to determine proper evacuation of a refrigeration system is - A micron gage. 14.7 Pisa is equal to - O Psig Electric is - The flow of electrons through a conductor. Voltage in an energized electrical circuit can be thought of as - Electrical pressure How is current flow measured in an electrical circuit? - With an ammeter A miliampere - 1/1000 of an ampere Whenever current flows through a conductor - A magnetic field wil be established around that conductor. If a conductor is moved though a field of magnetic flux - A current will be induced in that conductor. In an induction transformer the winding that receives the source voltage is called - The primary winding. If the primary voltage on a step down transformer is 110 volts and there is a 5:1 turns ratio, what is the secondary voltage? - 110/5 = 22 volts AC Given a domestic hot water heater with 4500/4500 watt elements and non simultaneous operation, what is the anticipated amp daw on an energized element when 220 volts is read at that element? - I= p/E. 4500/220=20.44 amps. Given a 1/2 hp blower motor that draws 6 amp. And 118 volts during operation. A wattmeter read 638. What is the power factor for this circuit? - Pf= wattmeter reading/ v x a reading Pf= 638 watts/ 118 x 6 = 0.90. A diode in an electronic circuit - Acts as a conductor in one direction and as an insulator in the other direction. What happens to the voltage in a series circuit - It divides across wash of the loads. What happens to the current in a series circuit - It is the same at any point in the circuit. What happens to current in a parallel circuit? - It divides across each of the loads. What happens to the voltage in a parallel circuit? - It is the same at any point in the circuit. What should the voltage reading be across a good set of closed contacts in an energized circuit? - 0 volts. What should the voltage reading be across a good set a open contacts in an energized circuit? - The applied voltage. What would cause a voltage drop across a set of closed contacts? - Pitting or dirt. Continuity refers - A continuous, uninterrupted circuit.