Service Course Review Flashcards
Service Course Review
What is this part called? (Be specific)
Direct spark ignitor
What is this part called? (Be specific)
Silicon carbide ignitor
What is this part called? (Be specific)
Inshot burner
What is this part called? (Be specific)
Silicon nitride ignitor
What type of burner is this?
Upshot burner
What is this part called? (Be specific)
Flame rectification sensor
What is this part called? (Be specific)
Gas valve
What is this part called? (Be specific)
Flame rollout switch
What is this part called? (Be specific)
High limit switch
What is this part called? (Be specific)
Dual run capacitor
What is this part called? (Be specific)
Blower assembly
What is this part called? (Be specific)
Condenser fan motor
What is this part called? (Be specific)
Contactor
What is this part called? (Be specific)
Reciprocating compressor
What is this part called? (Be specific)
Evaporator coil
What is this part called? (Be specific)
Circuit board / control board
What is this part called? (Be specific)
Heat exchanger
What is this part called? (Be specific)
Inducer motor
What is this part called? (Be specific)
Piston / metering device
What is this part called? (Be specific)
Pressure switch
What is this part called? (Be specific)
Burner assembly
What is this part called? (Be specific)
Scroll compressor
What is this part called? (Be specific)
Squirrel cage
What is this part called? (Be specific)
Thermal expansion valve (TXV) / Metering device
What is this part called? (Be specific)
Transformer
What is this part called? (Be specific)
Manual disconnect switch
What is this part called? (Be specific)
Expansion tank
What is this part called? (Be specific)
Super boost
What is this part called? (Be specific)
In line fuse
What is this part called? (Be specific)
Surge protector
What is this part called? (Be specific)
Auto fill valve
What is this part called? (Be specific)
Air seperator
What is this part called? (Be specific)
Mixing valve
What is this part called? (Be specific)
ECM Protector
What is this part called? (Be specific)
Dirt magnet
What is this part called? (Be specific)
Circulating pump
What temperature do flue gases condense at?
135°f and less
What is this part called? (Be specific)
Thermocouple
What is this part called? (Be specific)
Thermopile / Powerpile
What determines the acidity of condensate?
Amount of carbon
We are there to prevent _.
Headaches
If the blower wheel is dirty the amperage will go?
Up
If the evaporator coil is plugged the blower motor amperage will go?
Down
How often should burners be cleaned?
Every 4 years (Sooner if using propane or if equipment has not been maintained)
Why do we need to clean / replace the burners?
Bad burners will blow your heat exchanger and a new heat exchanger will be very expensive. The number one reason of heat exchanger failure is bad burners.
Will also make the furnace burn very inefficiently, which will increase energy bills
What are 8 ways to tell a burner is failed/failing? (Be specific)
1.Rust in the carry over tracks
2. Impingement on the interior of the heat exchanger
3. Flame colour
4. Equipment efficiency
5. Dancing flame
6. Flame rollout
7. Delayed ignition
8. Combustion analysis
What enters where the yellow arrow is pointing?
Primary air
What enters where the blue arrow is pointing?
Secondary air
What enters where the red arrow is pointing?
Fuel
Which part of the burner is the yellow arrow pointing towards?
The venturi
Dirty burners do irreversible amounts of damage to which components?
1. Heat exchanger
2. Flame rectification sensor / Flame rod
3. Ignitor
What can be offered when a customer has dirty burners?
Offers:
1. Remove and clean burner assembly
2. Install stainless steel burners
3. Replace due to failure / Replace preventatively
Addition offers:
1. Replace flame sensor / flame rod
2. Replace ignitor
How often should ignitors be replaced?
It is recommended that your ignitor be replaced every 5 years due to expected lifespan
Which type of hot surface ignitor is extremely fragile?
Silicon carbide
What temperature do hot surface ignitors reach?
2400°f
What is the purpose of a hot surface ignitor?
To INSTANTANEOUSLY ignite the flame
Ignitor amps should be higher/lower compared to its rating?
Higher
As ignitors expand and contract their resistance _
Increases
What are 5 ways to determine an ignitor is failing/failed?
1. Low amperage
2. Spotted or marked
3. Insulated
4. Delayed ignition
5. Broken
What do you tell a customer when explaining why a hot surface ignitor should be replaced?
We need to replace your ignitor because a bad ignitor will cause improper combustion and can result in flame rollout or delayed ignition. Your ignitor must reach 2400°f for proper combustion.
What is the purpose of the flame rectification sensor?
To prove cross burner ignition
What unit of measurement is used when testing a flame sensor?
µA (Micro amps)
How many µA (micro amps) are in an amp?
1,000,000
What is a poor reading when testing a flame sensor?
2.2 or less µA (micro amps)
What is an ideal reading when testing a flame sensor?
2.5-10 µA (micro amps)
What is the base of a flame sensor made of?
Porcelain / Ceramic
How does a flame sensor prove cross burner ignition?
Flame ionization
What unit of measurement is used when testing a thermocouple / thermopile?
mV (millivolts)
How many mV (millivolts) are in a volt?
1,000
How many mV (millivolts) should you expect to see in an open test of the part pictured?
30mV
How many mV (millivolts) should you expect to see in an open test of the part pictured?
750mV
How many mV (millivolts) should you expect to see in a closed test of the part pictured?
15mV
How many mV (millivolts) should you expect to see in a closed test of the part pictured?
350mV
A thermocouple is a safety control.
True/False
True
A thermopile / powerpile is a safety control.
True/False
False
What is the purpose of a thermopile / powerpile?
Generate enough power to open the gas valve
Thermocouple / Thermopiles are power __________ .
generators
A failed / failing flame sensor can cause?
Short cycling
What do you tell a customer when explaining why a flame sensor should be cleaned / replaced?
We need to clean or replace the flame sensor because a bad flame sensor is very innefficient and will cause short cycling of the furnace that can damage ignitors, switches, and motors from starting frequently.
Just like starting your car over and over it is damaging your engine and using a ton of fuel
How often is it recommended to replace a flame sensor?
Recommend replacement every 5 years.
What is flow through?
When the gas valve is de-energized and still marginely open causing candelling or small amounts of gas to leak at the orifice.
Can be cause by dirt or debris not allowing the gas valve to fully seat closed or a faulty valve.
What 2 voltages are gas valves controlled by?
1. 24v
2. 350mV
What is the purpose of a gas valve?
To regulate fuel output to the equipment
Controls equipment efficiency
Why are the ignitor and flame sensor almost always placed on oposite ends of the burner assembly?
Prove cross burner ignition
Determing the efficiency if the input of the appliance is 116,000 BTU/H and rthe output is 92,000 BTU/H
79%
92,000 ÷ 116,0000 = 0.79
Determing the output if the input is 140,000 BTU/H and the piece of equipment is 93% efficient
130,200
140,000 x 0.93 = 130,200
Determine the input if the output is 76,000 BTU/H and the efficiency is 80%
95,000
76,000 ÷ 0.80 = 96,000
What are the 5 steps to conducting a high limit test?
1. Fire the furnace
2. Remove the limit leaving the wires connected
3. Insert thermometer in limit cavity
4. Let equipment run for 15 minutes
5. Check temperature rise while equipment is running
Stay with equipment at ALL TIMES while it is running
-If temp does not exceed that of the rating on the limit switch than the switch it faulty
-If the temp does exceed that of the rating on the limit than there is another cause for the limit tripping
A high limit is a normally __ switch
open/closed
closed
A fan limit is a normally ___ switch
open/closed
open
A flame rollout is a normally ___ switch
open/closed
closed
A switch reading L170-40 will open at what temperature?
170°f
A switch reading L170-40 will close at what temperature?
130°f
A switch reading F140-20 will open at what temperature
120°f
A switch reading F140-20 will close at what temperature
140°f
Why does a flame rollout switch have a manual reset?
To prevent the customer from cycling furnace power without having a licensed technician investigate the cause of the rollout
How many CFM per ton for an air conditioner?
400cfm
How many CFM per ton for a heat pump?
450cfm
What is the difference between delayed ignition and flame rollout?
Delayed ignition is a buildup of gas before being ignited.
Flame rollout is when the flame has nowhere to go.
What do we tell the customer when we need to replace a safety limit switch?
We need to replace the safety limit switch because safety limit switches are there to protect your equipment from overheating and prevent a hazardous situation.
What do we offer when a safety limit switch has failed or is failing?
Offers
Replace preventatively or replace due to failure
Additional offers
Blower cleaning
Rollout switch
Maintenance - gas pressures
What do you tell a customer when a gas valve is failing / failed?
We need to replace the gas the gas valve because a faulty gas valve can drastically reduce equipment efficiency and can become hazardous. Gas valves with flow through or that are out of calibration can do irreperable damage and ultimately prevent the furnace from working completely.
What is a byproduct of burning refrigerant?
Phosgene gas
How much does 1ft³ of water wiegh?
62.4lbs
How often should a gas valve be replaced?
Never. A gas valve should last the lifetime of the equipment.
If a gas valve has come in contact with water and has begun rusting what are you required to do?
A tag the equipment.
A gas valve is a safety device and must not come in contact with water.
What type of equipment only has a primary heat exchanger?
Non-condensing equipment
Heat exchangers must be sloped? And why?
Must be sloped forwards to prevent condensation from pooling at the back and rusting out the secondary heat exchanger
What are 3 ways to test a heat exchanger for failure?
1. Visually
2. Combustion analysis
3. Smoke bomb
What do you tell a customer when they need to replace their heat exchanger?
We need to replace the heat exchanger because the combustion analysis is showing CO at dangerous levels and can cause death! We need to shut down the appliance immediately for your safety
How often should you need to replace your heat exchanger?
NEVER, your hx should have lifetime warranty however if the burners are not taken care of every 2-3 years it will destroy your heat exchanger, As well as other causes like high gas pressure, plugged secondary or blower wheel. All preventative during maintenance
What is the max temperature for slab in-floor heating? And why?
120°f
To prevent cracking in the concrete
What is the maximum temperature for cast iron radiators?
140°f
What is the maximum temperature of baseboard fin tube radiators
160°f
If you have water in the blower assembly you most likely have?
Leaking secondary heat exchanger
Heat exchangers are designed to maintain a temperature rise of?
30-60°f
Is a trap needed on a collector box? Why?
Yes
To maintain a neautral pressure and prevent the inducer motor from pulling in ambient air and causing a water backup
What type of heat exchanger is pictured?
Stainless steel self cleaning fire tube
What type of heat exchanger is pictured?
Brazed plate
What type of heat exchanger is pictured?
Shell and tube
Where do you often see shell and tube heat exchangers?
Pool heaters
What do you tell a customer when their heat exchanger is failing/failed and needs to be replaced?
We need to replace the heat exchanger because the combustion analysis is showing CO at dangerous levels and can cause death! We need to shut down the appliance immediately for your safety
How often should a heat exchanger need to be replaced?
NEVER
Your hx should have lifetime warranty however if the burners are not taken care of every 2-3 years it will destroy your heat exchanger, As well as other causes like high gas pressure, plugged secondary or blower wheel. All preventative during maintenance.
A heat exchanger that is not condensing is ____ efficient.
more/less
less
Every heat exchanger that is not condensing is on average 35% less efficient
The faster the air flows through the heat exchanger the ____ heat it will transfer and the _____ its temp rise will be.
more/less
higher/lower
The faster the air flows through the heat exchanger the more heat it will transfer and the lower its temp rise will be.
What are 3 additional things you can offer when a heat exchanger is failing/failed?
Additional offers
1. Stainless steel burners
2. Blower and secondary heat exchanger cleaning
3. New furnace
Ideally your inducer amperage will be ____ than its rating?
higher/lower
lower
Inducer motors always have start capacitors?
True/False
False
Inducer motors have run capacitors
Can we change capacitors on inducer motors? Why?
No.
If the capacitor on an inducer motor is failing it is because it is discharging due to motor beginning to fail.
Which wire should an ammeter be placed around?
Hot/Neutral/Ground
Neutral
What tool is used to measure the rotation speed of the motor shaft on a rooftop/package unit?
Tachometer
What are 4 ways you can identify an inducer motor is beggining to or has failed?
1. Visually
-Rust
-Cracking / breaking
-Oil leaking
2. Listening for rattling or bearing wear
3. Using a manometer on the pressure switches to determine the amount of draft being pulled
4. Amperage is higher than RLA rating