Pilots, Pilot Burners, Thermocouples And Thermopiles Flashcards
4 types of pilots
Continuous
Expanding
Intermittent
Interrupted
A continuous pilot( also known as_____) burns 24/7
Standing pilot
What is an expanding pilot and how does it work
Hybrid of a continuous, the flame is always lit but at a much smaller size. Increases in size when there’s a call for heat
What is an intermittent pilot
Only ignited when there is a call for heat usually by spark, pilot remains on throughout burner cycle and is extinguished when main burner cycles off
What is an interrupted pilot
Similar to interment pilots, expect that the pilot extinguishes when the main burner has ignited, monitored by a separate flame sensor
Where are non aerated pilots found use what type of air
Clothes dryers and gas cooking
Secondary
Pilot orifices are what color for natural gas and propane, which one has the larger orifices
Nat gas is silver metallic
Propane is brass
Nat gas has the larger orifices
Most common pilot light is?
The post aerated pilot light
What are the main functions of the pilot
Ensure ignition of main burner and main safety device with thermocouple
Secondary Safety feature in pilots is called, what does it do
Proved pilot, shuts off main burner, and sometimes pilot burner
Difference between safe hook up and 100% safe hook up
Safe hook up main burner gas is shut off pilot gas is not. 100% turns off pilot light and main burner
You should always replace the thermopile with the same millvoltage out put. True or false
True
How long does it take the thermocouple to heat up
30 to 60 seconds
All propanes system must be a safe hook up or 100% safe hook up
100% safe hook up
How tight do you turn a thermocouple connection
No more than one quarter turn beyond finger tight
What is an ECO
Energy cut off switch, another name for high limit
Why do thermopiles have extra voltage
Used to operate both the safety device and control valve to main burner
What happens if your thermocouple gets excessive heat
Excessive heat will prematurely burn out thermocouple
What is the acceptable voltage range for an open circuit
17mv to 32mv
What is the acceptable voltage range for an closed circuit what is needed to complete the test
A test adapter is needed
8mv to 17mv
Drop out range is, what does that mean for the thermocoupler
0.75mv to 6 mV, needs to be replaced
If a gas valve fails, what position does it fail in?
Closed
When should the turndown test be done?
On appliances under
And exceeding 400mbh
Response time shall not exceed how long? Can be detected by?
180 seconds, an audible click as gas valve snaps closed.
What is response time
The time it takes the thermocouple to cool and cause the power unit to de-energize gas valve
What will happen if the relief port is blocked in a diaphragm gas valve?
Pressure can not escape, and the valve remains closed
What position does the actuator in a diaphragm gas valve end up if the diaphragm ruptures?
The actuator remains closed
Junctions of a thermocouple are called
Hot and cold
If mV fall into this range What should you do
Check pilot flame and electrical connections
What are these 5 descriptions on the test chart
- Check pilot flame and electrical connects
2.acceptable range
3.check power unit
4.replace thermo coupler
5.drop out range
All pilots must be equipped with what
A mounting bracket and fastened on main burner to ensure satisfactory ignition.
What are orifices designed to do
Control Gas flow
What high limit safety switch comes with a manual rest
Flame rollout
What is the recommended spark gap for the pilot ignition spark?
⅛”
What happens if the burner flame impinges on the burner or any other metal source
The flame will cool and cause incomplete combustion
Describe aerated pilots
Uses primary air and a mixing tube
Describe non aerated pilot
Uses only secondary air, slight yellow flame
When converting nat gas to propane what do you need to do?
Change gas orifices, pilot orifices, gas valve
When you depress the knob.on the gas vavle what happens.
The power unit closes the gas unit opens
