G - Pilots, pilot burners, thermocouples and Thermopiles

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What is an Interrupted pilot

Ignited when there is a call for heat but goes out when the main burner is lit

What is a drop out point

A closed circuit milli voltage reading at the instant the plunger is released by the electromagnet

What is a proved pilot

Activation of a flame failure device

Can you use a joint compound on thermocouple threads

No

Can a pilot orifice be re drilled

No. It is made of pot metal

What is an intermittent pilot

Only ignited when there is a call for heat

What is an ECO

an energy cut off or high limit switch

What is power unit

Enegerized by the thermocouple or Thermopile and holds the safety gas valve open or safety switch closed

What is the main function of a pilot burner

Ignite the main burner

How do you do a safety shutdown test

Ignite the main burner and disconnect the thermocouple. The burner should then off immediately

How much power is used to operate the blower motor

Line voltage (110 or 120)

How is a pilot burner usually ignited

Manually

What is pull in voltage

Minimum milli voltage output of the Thermopile required to energize and open the gas valve to the main burner

What is a post aerated pilot burner

Most popular and common residentialy and light commercial appliances. An air duct beside the flame burns out dust and debris Also called incineration or target

What is the secondary function of a pilot

Operate flame failure devices by heating the thermocouple or Thermopile

What will excessive heat to the Thermopile cause

Premature burn out

What is an aerated pilot burner

Produces a sharp blue flame but the primary air inlet is susceptible to blockages causing the flame to carbonize. Important to frequently clean

What German physicist discovered that heat can create electricity

T.J. Seebeck

What is safe hookup

The automatic safety control is limited to only the main burner so if the pilot goes out gas will continue out of the main orifice. Prohibited for use in propane

What is an expanding pilot

The flame is always burning much like the continuous but the flame is increased when it lights the burner

How does a thermocouple work

The pilot applies heat to the thermocouple. The lead transports voltage to the power unit and if the heat is removed there is no power to hold it open

What must be done to a combination valve if an appliance is used on a propane installation

The regulator must be bypassed and the valve is operated in a fully open position

What is response time

The time it takes the thermocouple to cool sufficiently to cause the electromagnet to de energize and close the gas flow off

Where should a pilot flame be on a thermocouple

The top 3/8" to 1/2"

What is a non aerated pilot burner

Uses only secondary air to achieve combustion. Often found on gas stoves and clothes dryers Also called non linting or non primary

Where should the lead not be bent

Within 1/2" of either end it cannot be bent and shouldn't within 1" of either end

What is the maximum temperature of the ECO

the same as the temperature setting of the pressure relief valve (usually 200 to 210 F)

What is the difference between and open circuit milli volt check and a close circuit

You have to manually light the main burner to test on open You need a test adapter for closed as it will be normally operated

How is a pilots flame size adjusted

A needle valve

Where must a pilot be located

-Mounted where it can be safely lit -Properly positioned with respect to the main burner -Not exposed to falling debris during operation -Main burner flame should not touch the pilot -Must have ample air supply -Shall not recieve full force of main burner -Shall light the main burner under all conditions -never impinge on a burner or any other surface

How tight should a thermocouple be

1/4 turn more than hand tight

How much power should the thermocouple produce on an open circuit test

17 to 32 mV

What shall a response time not exceed on a unit 400,000 BTU

180 seconds on both natural gas and propane

How much power is used to operate the main control in a burner

24V

What voltages can a Thermopile produce

250 to 1000 mV

How long should it take the pilot to light the main burner

4 seconds

What shall the response time not exceed on a unit over 1 million BTU

4 seconds for both natural gas and propane

How much larger must the grounding are be than the flame sensor

How much should a thermocouple produce on a closed circuit test

8 to 17 mV

What is the maximum length you should use on a Thermopile

80 feet

What shall the response time not exceed on a unit 400 MBH to 1 million BTU

90 sec natural gas 20 sec propane

What are the three pilot burner designs

Aerated Non aerated Post aerated

What is a turn down test

Also known as effective ignition test. Conducted to ensure that the pilot will satisfactorily ignite the main burner when it is reduced in size enough to prevent drop out. Factors such as a dirty pilot can cause this

How does a safety valve work on a power unit

An electromagnet attracts the plunger and holds it in the open position. A manual reset button must be depressed and held while lighting

When replacing a thermocouple what size should you use

As close as possible to the original

What is 100% safe hookup

Automatic safety control that shuts off both the main burner gas and the pilot gas

How much power should the thermocouple produce

Between 17 and 32 mV

What is a continuous pilot

Burns 24 hours a day 7 days a week whether or not the main burner is fired

What is a thermopile

Consists of several thermocouples connected in series. Therfore the total milli voltage output is higher than that produced by a single thermocouple

What are the 4 types of pilot burners

Continuous (standing) Expanding Intermittent Interupted


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