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District of Columbia-HVAC Heating and Air Conditioning Online Practice Test

These are actual questions from our online practice test.

We have included a question from each chapter of the test. Every question will be multiple choice. The answers are not included with the sample.

Sample Questions

# Chapter Title Question
1 Temperatures, Furnaces, Valves and Hydronics

Excessive heat or pressure may cause the system to fail. At least one combination over-temperature and over-pressure relief valve is always fitted to the system to allow the steam or water to vent to the atmosphere in case of the failure.

2 Compressors, Ducts, Furnaces and Exhaust Hoods If the ignition on a gas boiler is not achieving a spark you should check ____________.
3 Compressors, Refrigerants, Valves, Air Conditioning and Thermostats What are the two types of compressor drives?
4 Evaporators, Lubricants, Pipelines and Water Pressure The shell of a shell and tube or shell and coil condenser acts as __________.
5 Water Use in HVAC Systems Through the use of variable speed pumps, ______________ water systems are realizing greater efficiencies.
8 Solar Thermal Panel Wiring, Installation and Equipment

#8 AWG THHN/THWN-2 Stranded Copper PV Cable

500ft Spool

Available colors: Black, Green, Red, White, Blue

  • 90°C Dry - 75°C Wet/600 Volts
  • Gasoline and Oil Resistant II
  • Machine Tool Wire

(Stranded): 90°C Dry

  • Appliance Wire: 105°C Dry



  • _________________ volt building wire for use in commercial and industrial applications 
  • 14 AWG - 2 AWG is marked VW


  • Color coded, heat and moisture resistant PVC (polyvinyl chloride)


  • Nylon (polyamide), clear on 14 AWG - 2 AWG colors
  • Nylon on 8 AWG - 2 AWG black
9 Solar Collector Installation Insulated pipes to and from collectors should be buried _____ , in ground-mounted systems.
10 Solar Thermal Systems, Panels, Collectors and Formulas

 Assuming that the average COP of the heat-pump water heater is 2.0 — a fairly conservative assumption — it takes 0.0855 kWh to raise the temperature of a gallon of 50°F water to 120°F. So 2,000 kWh can produce ______________________ gallons of hot water a year, or 64 gallons a day — exactly equal to the amount of hot water that the U.S. Department of Energy assumes is used by the average American family. So, once you’ve paid for the system, you get “free” hot water.

11 Solar Thermal, Electric Currents and Formulas

The actual power density varies slightly since the Earth-Sun distance changes as the Earth moves in its elliptical orbit around the sun, and because the sun's emitted power is not constant. The power variation due to the elliptical orbit is about 3.4%, with the largest solar irradiance in January and the smallest solar irradiance in July. An equation  which describes the variation through out the year just outside the earth's atmosphere is:

H is the radiant power density outside the Earth's atmosphere (in W/m2);
Hconstant is the value of the solar constant, _____________ kW/m2; and
n is the day of the year.

12 Pipe Configurations and Pipe Systems Regarding removal of pipe, the line shall be first disconnected from all sources of gas and then thoroughly purged with __________, water, or inert gas before any cutting or welding is done when piping containing gas is to be removed.
13 Gas Pipes, Vents and Pumps It takes centrifugal force to produce flow for the ________________ pump.
14 Two Pipe Cooling and Heating Systems _____________ % of cooling speed in heating can be generated through the modern two pipe system which has variable sized pumps, operating at high speed in cooling and reduced speed.
15 Distribution Systems In doing a kW analyses or wire to water efficiency test the secondary pumping system motor should be run at no less than _______________ hp.
16 System Applications A water temperature of 200 degrees F with an absolute viscosity, (cP) of 0.30 = a kinematic viscosity, ft 2/s of 0.__________ X 10-5.
17 System Design Data If a water system is operating at 75 psig pressure at an altitude of 1000 ft the atmospheric pressure is 14.2 lb/in 2, so the absolute pressure is ___________ psia.
18 Pump Description The two principal types of centrifugal pumps for HVAC are axial flow pumps and __________ pumps .
19 Installation and Ductwork Gas supply line to a mobile home is commonly _______ inch.
20 Motor Controls and Occupancies Energy sources used for HVAC include electricity and ________.
21 Speed and Curves What is NPSH?
22 Friction A measure of channel flow efficiency is the definition of Hydraulic _________________.
23 Insulation 0
24 Excavating, Clearing Site and Trenching The minimum depth that all stumps should be cleared away in embankment areas is what?
25 Paving, Subsurface, Drainage and Hot-Mix Paving

If the air void are above ___ to ____ %, the mix will permeable to air and  water and will not have the required durability.

26 Installation and Troubleshooting Flame rod sensor proves the presence of a pilot or _________ flame.
27 OSHA Safety, Dig Alert, Asbestos and Code of Federal Regulations, Title 29, Part 1926 According to the APWA Uniform color code, the color red identifies ___________.
28 Employees, Contractors, Insurance, Safety and Fire Extinguishers On a jobsite, you have to have a fire extinguisher for safety purpose within:
29 Basic Blueprint Reading and Plans ____________ lines indicate an entire length in a small space.
30 Basic Estimating and Mathematics

Convert  6 2/3     into an  improper fraction

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