Standard Furnace Components Flashcards by Chase Wilson-Dull

List the different configurations of a furnace

Up flow
Down flow
Horizontal

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Why is a thermostat better for controlling the furnace than a light switch

Set to turn on when the temperature drops below a certain temperature

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One there is a call for heat in a furnace what happens next

Completes electrical circuit that opens gas valve

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3 examples of operating controls

Thermostats
Fan controls
Transformers
Gas valves
Motors

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Give 3 examples of safety controls

Limit switches
Thermocouple

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List the different types of standing pilots

Aerated
Post aerated
Non aerated

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What is the range of voltage that a thermal couple can produce

20-30 millivolts dc when heated

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How much should the flame surround the thermal couple tip

3/8- 1/2

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Define thermopile

Thermocouples wired in series

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Another name for thermopile

Power pills or pilot generators

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What components make up the flame safeguard

Disc, plunger, dropout spring, pole piece, electro magnet

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What energizes the power unit

Power from the thermocouple energizes the electromagnet in the power unit

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What keeps the plunger in the power unit closed

Electro magnet

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Combination gas valve components, list them

On pilot off knob
Pressure regulator
Power unit
Thermocouple connection
Pilot adjustment
Electrical connections
Operator
Pilot connection
Gas inlet
Gas outlet
Pressure tap

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What is normally used to detect temperature in a temperature sensing device

Bi metal strip expands and contracts
Hot junction and cold junction

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List the different types of temperature sensing devices

Strip type
Spiral type
Disc type
Bellows type
Liquid bulb type

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What are different categories of thermostats

Mechanical
Electronically

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What are the possible contacts in a mechanical thermostat

Mercury bulb

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Describe the purpose for a heat anticipator

Prevents temperature overshooting

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The variable heat anticipator need to be set to match what

Must Match the current draw of the control circuit

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Electronic thermostats use what type of temperature sensor

Thermistor

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List the possible ways that an electronic thermostat receives power

Can be battery powered or powered from the control circuit ( power stealing)

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What’s an advantage about a programmable thermostat

Program different times you want the heat on

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List the setting for fan control

Fan on: between 120-140
Fan off: between 90-100

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If a high limit control were to open what would it cut power too

Gas valve will lose power and close stopping flow of gas

Where are roll out switches located

Above the burners

What does a combination fan/ limit control use for temperature sensing device

Bi metal

What is the max temperature setting for a high limit switch

250f

Describe the primary windings in a transformer

Connected to the power source which brings power into the transformer, wraps around an iron core

Describe the secondary winding in a transformer

Also wraps around the core and is used to power a load

How does a transformer operate

Magnetic induction

What style of transformer is used more often in hvac

Step up transformer

How are transformers rated

Va rating (volts x amps = watts

List the parts in a fan belt driven motor

Shaft, keeper, pulley

Describe heat exchanger

Transfers heat produced by burners

What is the purpose of a draft diverter

Provides a pressure balanced flue

What is the job of a burner

Transforms combustible fuel into heat

What are the two different types of burners

Up shot In shot

List the parts of a burner

Mixer head Mixer face Primary air shutter Mixer throat Venturi tube Orifice Burner ports Burner head

What regulates the amount of air entering a burner

Primary air shutter

List what information can be found on a rating plate

Approval agency Orifice sizes Altitude I put rating Fuel type Electrical requirements

How many milivolts are in 1 volt

1/1000 v

What is the most common thermopile voltage

750 milivolts

Which way should the ladder diagram be read

Left to right

When a schematic is shown is the power on or off

Power off

A milivolt system is good because it can run a control system without the presence of line voltage, what are the disadvantages

Amount of controls it can operate Length of wire Power generated by thermopile weakens over time

What color is the hot wire in an electrical circuit

Black

What color is neutral in a electrical circuit

White

What are our limits when working with electricity

Servicing or changing controls Repairing wires Making minor upgrades to existing hvac systems

Who should work on electrical panels

Electricians

What does a flow chart represent

The process of how the equiptment operates

What is the Sequence of operation for a furnace

Pilot on Call for heat Burner ignite Fan comes on System runs until call for heat ends Thermostat reaches temp ending call for heat Burner shuts down fan keeps running Fan shuts down ending heat cycle

What is an expanding pilot

Hybrid of continuous pilot, flame is always lit but at a much smaller size than required

What is the difference between an intermittent and an interrupted pilot

Only ignited when there is a call for main burner ignition- pilot flame extinguishes when main burner has been ignited

What does HSI stand for

Hot surface ignition

What is the most common pilot used in todays industry

Aerated

What is the color of the pilot orifices for natural gas and propane gas

Silver and brown

All pilots must be equipped with?

Mounting brackets

Thermocouples have ?

Hot and cold junctions

What is a safety shut down test

Disconnecting the thermocouple lead from the control, main burner shoild shut off

What is another name for a high limit switch

ECO energy shut off

A flame should enevelop the thermocouple how much

3/8 to 1/2

What color should the flame be on a pilot light

Blue as possible

A thermocouple should read what on an open circuit

32 open 17 closed

The response time on a gas valve should not exceed how much time

180 seconds for standing pilot appliances up to 400 MBH

What does a step down transformer do and how is it rated

Steps down voltage from 120 to 24 It is Va rated

What type of control is a fan switch

Operating

How can an appliance be denergized

Door switch, breaker, furnace switch

Name three instruments used to determine gas pressure of an appliance

U tube, digital, analog

What is the proper manifold pressure for natural gas

3.5” wc

What is the proper manifold pressure for propane

11” wc

How can you test a transformer to see if it’s functional

Continuity test

What are the three designations for the wires in the line voltage circuit

Hot, neutral, ground

Standard Furnace Components Flashcards

(73 cards)