HVAC Vol 4

(601) How is static electricity best controlled?

Grounding, bonding, humidifying

(601) Grounded wires carrying off static charges

neutralizes the difference in electrical potential

(601) A fuel spill should be reported when how many gallons or more is leaked or spilled?

25

(601) A leak of 35 gallons should be reported to the state regulator within

24 hours

(602) When the viscosity of an oil is decreased, how does it affect the oil?

Easier to pump

(602) Which type of condition could cause a blocked burner?

Sludge in oil

(603) Which procedure is best to use for efficiency if the tank is below the level of the burner?

A two-stage pump with a two-pipe system

(603) Why is a galvanized pipe not used with fuel lines?

It can cause corrosion problems

(603) Why is a gate valve located on the tank side of the strainer?

So that the suction line is isolated when cleaning the strainer

(604) Liquefied petroleum gas (LPG) is stored and transported in

it liquid state

(604) Ten percent of a liquefied petroleum gas (LPG) tank is not filled to

accommodate for expansion

(605) The action that happens to the safety shutoff valve in the main burner line once a pilot flame is detected is it

is opened

(605) Which device removes any accumulated gas in the combustion chamber burner?

Blower

(606) What are the three categories of gas supply systems?

Low, medium, and high

(607) Identify what you would use to determine if water is in the oil

Tank stick with water finding paste

(608) Identify all necessary elements that must be present for combustion?

Heat, air, and fuel

(608) How much of the flue gases are made up of nitrogen?

79%

(608) Why is carbon monoxide undesirable in flue gases, besides the fact that it is dangerous?

Its presence in flue gases represents a waste of fuel

(608) The turndown of a burner is the ratio of the

maximum firing rate to the minimum firing rate

(609) Identify the relationship between excess air and complete combustion

Excess air is needed for complete combustion

(609) The condition that affects infiltration losses is the volume of

outside air that leaks through cracks and crevices

(610) A pressure-gun burner achieve flame turbulence by

causing the air to whirl as it leaves the gun tube

(611) The effect too much air has on a flame is that it makes it

short, noisy, and tends to pull away from the burner

(611) Identify the cause of a high CO2 reading during combustion

Insufficient draft and over firing

(612) Where does the signal to open and close a gas valve come from on modern equipment?

Control board

(613) Ho does an inspirating burner bring in primary air?

Venturi action

(613) The pulse burner introduce gas and air

in operating phases

(613) Where does gas and primary air mix in a premixing burner?

Before they reach the burner port

(613) How long will an intermittent pilot stay lit?

During the entire run period

(614) The mixture of air is affected by a reduced gas velocity because it allows for

complete mixing before it exits the burner ports

(615) What affects the voltage generated by a thermocouple?

Temperature difference between hot and cold junctions

(615) The relationship between a sensing thermocouple and a standing pilot is the

thermocouple senses the standing pilot and determines if it is lit correctly

(615) Hot-surface ignitors are located in relation to gas flow by a location in which

gas will pass over it when the gas valve opens

(615) The way the control module can determine if the glow coil is hot enough to ignite the fuel is due to the resistance of

glow coil or a time delay

(615) A solid-state device can detect the presence of a flame because the pilot flame conducts the

current to the grounded pilot

(616) Which type of work is checked for completion during the pre-operational inspection of a gas burner?

Installation, repair and cleanup work

(616) Identify what the thermocouple is inspected for during pre-operational inspection?

Carbon deposits, corrosion or heat damage

(616) How long should you wait for gas to clear from the combustion chamber?

5 minutes

(617) How often should you remove, dismantle, and clean a main burner?

At least once a year

(618) A forced draft affect oil burners because it

increases their oil burning capacity

(618) The effect a nozzle has on high pressure oil passing through it is it

produces a fine mist

(618) A gun type burner get its 10,000 volt electric spark from the

step-up transformer

(618) Where is the high pressure gun type nozzle's angle of spray located?

On the side of the nozzle

(619) What is the combustion chamber inspected for during an oil burner pre-operational inspection?

Pools of unburned oil

(619) Which action should be taken if pools of unburned oil have flooded the combustion chamber?

Soak it up with rags and purge the combustion chamber

(620) How is the spark moved into the path of the oil spray?

Air from the fan will blow the spark into the path

(620) Which action should follow an air or oil pressure adjustment?

Flue gas analysis

(621) How do commercial burners vary their firing rate?

Electrically or electronically according to the load demand

(622) Why should you not use photocells to detect gas flames?

Because a well-adjusted gas flame emits too little visible light

(622) How does a cad cell detect light from an oil flame?

Light-sensitive cadmium sulfide

(622) A factor the flame rod system depend upon is the

flames ability to conduct current when an electrical potential is applied across it

(623) The purpose of the preignition function is to ensure

there is an arc when the oil starts to flow

(624) What is a common cause of overheating the heat exchanger on a gas fired burner?

The blower not running

(625) Identify the purpose of the draft hood

Maintain constant head on the combustion system

(625) Which device(s) creates the resistance that blowers must overcome?

Furnace air passageways, filters, and ductwork

(625) Where does return air enter on an upflow furnace?

Through the bottom or side of the blower compartment

(625) Negative pressure is corrected in a well-sealed building by installing

a make-up air unit

(626) How is the furnace fan control connected with the blower motor?

In series

(627) When the thermostat is turned down past the ambient temperatures the burner should

shut off

(627) Which action is the first step in checking the safety limit control?

Turn power OFF and disconnect the blower circuit

(628) Which type of control is not usually located on the radiant heater?

Thermostat

(629) Which inspection process is performed after the radiant heater pre-operational inspection?

Operational test

(629) How many seconds should the thermostat be turned off to take the system out of lockout?

60

(630) What should be done before making any thermostat adjustments for a forced air furnace?

Ensure no exposure from heat or too cold from windows, doors or drafts

(630) The fan's OFF temperature setting is generally set for how many degrees above the desired room temperature

5 to 10 F

(630) If you need to remove soot from the heat exchanger, what would you use?

Vacuum cleaner

(631) How is a radiant heater's combustion air intake inspected?

Disconnect air intake and inspect internally using a flashlight

(632) Which effect does an increase in pressure have on the boiling point?

It increases it

(632) Which formula is correct when you need to determine the temperature of water in a steam boiler?

square root of the psi x 14+198

(633) Where is the internal feed pipe located in a steam boiler?

In the water space near, but not touching, the bottom of the steam drum

(634) What must the mechanical draft systems overcome?

All draft losses

(635) water-hammer is avoided in the piping system by using

flashtanks

(635) What does the probe-type low water cutoff depend on to operate?

The flow of a low electrical current

(636) Feedwater attaches to discharge below the boiler water line so it

doesn't disturb normal water circulation

(636) The check valve location is in the feed line

near the boiler

(637) Why are condensate returns necessary?

Because some steam converts back to water

(638) Thermostatic traps react to a difference in

temperature between steam and condensate

(638) Condensate is subcooled in a thermostatic trap by allowing

it to back up in the trap and a portion of the upstream drip leg piping

(638) Which action does condensate trapped in a coil prevent?

Even steam distribution

(639) Which return water temperatures are condensing boilers designed to support?

Low

(639) Why are the internal parts and stack of a condensing boiler constructed of corrosion resistant material?

Because the condensation can become corrosive

(640) Why are make-up water requirements low in a closed boiler system?

The water circulates in the closed system

(640) Which characteristic affects the amount of water that flows through a pressure regulator?

Spring tension

(640) Identify the proper position of bypass valves during normal operation

Closed

(641) The action that will happen to the safety relief valve if the boiler and system rises above the set pressure of the valve is it will

open

(641) Identify the relationship between an aquastat's pump control pump control and cool water on a boiler

The control prevents the circulation of cool water

(641) Which connection prevents air and gases that are released from the heated water in the boiler, from entering the distribution system?

The diptube

(642) Which device operates the switch that stops power to the main burner on a float-type low water cutoff?

Float

(642) Which device does a hot water system use to handle the expansion and contraction of water?

Expansion tank

(643) Which type of tests should water gauge glasses be checked for during a pre-operational inspection?

Clear visibility of the gauge glasses from the operating floor

(644) Which position should the inlet and outlet valves of the circulators be in when filling a boiler system?

Open

(645) Identify what must be done if an expansion tank loses its air cushion

The tank must be charged

(645) How is only the water level raised in an expansion tank?

Open the air vent valve until desired water level is obtained

(646) How is diesel fuel supplied to the combustion chamber on a WH-400 system?

A motor-driven fuel pump

(647) How is the fuel mist ignited in a WH-400 system?

Sparks from the electrodes

(648) When will the heat control switch (HCU) energize the fuel burner motor and spark igniter on a 130k heater?

If sensor temperature is lower than programmed value

(648) Identify what the burner control unit do after ignition on a 130k heater

Monitors combustion through a photocell

(649) Identify the maximum circuit breaker size for a 130k heater

20A

(649) When does the "protective overheating switch-off" occur on a 130k heater?

When airflow is blocked by kinked ducts or blocked main air blower intake

(649) Which state will occur if the burner control unit (BCU) locks out and is reset three times during the same burner cycle on a 130k heater?

Latch-up