Parts and equipment systems Flashcards
Identify equipment components and their uses
1
Q
What is this part called? (Be specific)
A
Direct spark ignitor
2
Q
What is this part called? (Be specific)
A
Silicon carbide ignitor
3
Q
What is this part called? (Be specific)
A
Inshot burner
4
Q
What is this part called? (Be specific)
A
Silicon nitride ignitor
5
Q
What type of burner is this?
A
Upshot burner
6
Q
What is this part called? (Be specific)
A
Flame rectification sensor
7
Q
What is this part called? (Be specific)
A
Gas valve
8
Q
What is this part called? (Be specific)
A
Flame rollout switch
9
Q
What is this part called? (Be specific)
A
High limit switch
10
Q
What is this part called? (Be specific)
A
Dual run capacitor
11
Q
What is this part called? (Be specific)
A
Blower assembly
12
Q
What is this part called? (Be specific)
A
Condenser fan motor
13
Q
What is this part called? (Be specific)
A
Contactor
14
Q
What is this part called? (Be specific)
A
Reciprocating compressor
15
Q
What is this part called? (Be specific)
A
Evaporator coil
16
Q
What is this part called? (Be specific)
A
Circuit board / control board
17
Q
What is this part called? (Be specific)
A
Heat exchanger
18
Q
What is this part called? (Be specific)
A
Inducer motor
19
Q
What is this part called? (Be specific)
A
Piston / metering device
20
Q
What is this part called? (Be specific)
A
Pressure switch
21
Q
What is this part called? (Be specific)
A
Burner assembly
22
Q
What is this part called? (Be specific)
A
Scroll compressor
23
Q
What is this part called? (Be specific)
A
Squirrel cage
24
Q
What is this part called? (Be specific)
A
Thermal expansion valve (TXV) / Metering device
25
**What is this part called?** *(Be specific)*
**Transformer**
26
**What is this part called?** *(Be specific)*
**Manual disconnect switch**
27
**What is this part called?** *(Be specific)*
**Expansion tank**
28
**What is this part called?** *(Be specific)*
**Super boost**
29
**What is this part called?** *(Be specific)*
**In line fuse**
30
**What is this part called?** *(Be specific)*
**Surge protector**
31
**What is this part called?** *(Be specific)*
**Auto fill valve**
32
**What is this part called?** *(Be specific)*
**Air seperator**
33
**What is this part called?** *(Be specific)*
**Mixing valve**
34
**What is this part called?** *(Be specific)*
**ECM Protector**
35
**What is this part called?** *(Be specific)*
**Dirt magnet**
36
**What is this part called?** *(Be specific)*
**Circulating pump**
37
**What temperature do flue gases condense at?**
**135°f** *and less*
38
**What is this part called?** *(Be specific)*
**Thermocouple**
39
**What is this part called?** *(Be specific)*
**Thermopile / Powerpile**
40
**What determines the acidity of condensate?**
**Amount of carbon**
41
**We are there to prevent _.**
**Headaches**
42
**If the blower wheel is dirty the amperage will go?**
**Up**
43
**If the evaporator coil is plugged the blower motor amperage will go?**
**Down**
44
**How often should burners be cleaned?**
**Every 4 years** *(Sooner if using propane or if equipment has not been maintained)*
45
**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*
46
**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**
47
**What enters where the arrow is pointing?**
**Primary air**
48
**What enters where the arrow is pointing?**
**Secondary air**
49
**What enters where the arrow is pointing?**
**Fuel**
50
**Which part of the burner is the yellow arrow pointing towards?**
**The venturi**
51
**Dirty burners do irreversible amounts of damage to which components?**
**1. Heat exchanger**
**2. Flame rectification sensor / Flame rod**
**3. Ignitor**
52
**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*
53
**How often should ignitors be replaced?**
It is recommended that your ignitor be replaced every **5 years** due to expected lifespan
54
**Which type of hot surface ignitor is extremely fragile?**
**Silicon carbide**
55
**What temperature do hot surface ignitors reach?**
**2400°f**
56
**What is the purpose of a hot surface ignitor?**
**To INSTANTANEOUSLY ignite the flame**
57
**Ignitor amps should be higher/lower compared to its rating?**
**Higher**
58
**As ignitors expand and contract their resistance _**
**Increases**
59
**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**
60
**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.**
61
**What is the purpose of the flame rectification sensor?**
**To prove cross burner ignition**
62
**What unit of measurement is used when testing a flame sensor?**
**µA** *(Micro amps)*
63
**How many µA *(micro amps)* are in an amp?**
**1,000,000**
64
**What is a poor reading when testing a flame sensor?**
**2 or less µA** *(micro amps)*
65
**What is an ideal reading when testing a flame sensor?**
**2.5-10 µA** *(micro amps)*
66
**What is the base of a flame sensor made of?**
**Porcelain / Ceramic**
67
**How does a flame sensor prove cross burner ignition?**
**Flame ionization**
68
**What unit of measurement is used when testing a thermocouple / thermopile?**
**mV** *(millivolts)*
69
**How many mV *(millivolts)* are in a volt?**
**1,000**
70
**How many mV *(millivolts)* should you expect to see in an open test of the part pictured?**
**30mV**
71
**How many mV *(millivolts)* should you expect to see in an open test of the part pictured?**
**750mV**
72
**How many mV *(millivolts)* should you expect to see in a closed test of the part pictured?**
**15mV**
73
**How many mV *(millivolts)* should you expect to see in a closed test of the part pictured?**
**350mV**
74
**A thermocouple is a safety control.**
*True/False*
**True**
75
**A thermopile / powerpile is a safety control.**
*True/False*
**False**
76
**What is the purpose of a thermopile / powerpile?**
**Generate enough power to open the gas valve**
77
**Thermocouple / Thermopiles are power __________ .**
**generators**
78
**A failed / failing flame sensor can cause?**
**Short cycling**
79
**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*
80
**How often is it recommended to replace a flame sensor?**
Recommend replacement every **5 years**.
81
**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.*
82
**What 2 voltages are gas valves controlled by?**
**1. 24v**
**2. 350mV**
83
**What is the purpose of a gas valve?**
**To regulate fuel output to the equipment**
*Controls equipment efficiency*
84
**Why are the ignitor and flame sensor almost always placed on oposite ends of the burner assembly?**
**Prove cross burner ignition**
85
**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*
86
**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*
87
**Determine the input if the output is 76,000 BTU/H and the efficiency is 80%**
**95,000**
*76,000 ÷ 0.80 = 96,000*
88
**What are the 5 steps to conducting a high limit test?**
**1. Fire the furnace**
**2. Remove the limit leaving the wires connected**
89
**A high limit is a normally __ switch**
*open/closed*
**closed**
90
**A fan limit is a normally ___ switch**
*open/closed*
**open**
91
**A flame rollout is a normally ___ switch**
*open/closed*
**closed**
92
**A switch reading L170-40 will open at what temperature?**
**170°f**
93
**A switch reading L170-40 will close at what temperature?**
**130°f**
94
**A switch reading F140-20 will open at what temperature**
**120°f**
95
**A switch reading F140-20 will close at what temperature**
**140°f**
96
**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**
97
**How many CFM per ton for an air conditioner?**
**400cfm**
98
**How many CFM per ton for a heat pump?**
**450cfm**
99
**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.**
100
**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.**
101
**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*
102
**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.**
103
**What is a byproduct of burning refrigerant?**
**Phosphene gas**
104
**How much does 1ft³ of water wiegh?**
**62.4lbs**
105
**How often should a gas valve be replaced?**
**Never. A gas valve should last the lifetime of the equipment.**
106
**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.*
107
**What type of equipment only has a primary heat exchanger?**
**Non-condensing equipment**
108
**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**
109
**What are 3 ways to test a heat exchanger for failure?**
**1. Visually**
**2. Combustion analysis**
**3. Smoke bomb**
110
**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**
111
**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**
112
**What is the max temperature for slab in-floor heating?** *And why?*
**120°f**
*To prevent cracking in the concrete*
113
**What is the maximum temperature for cast iron radiators?**
**140°f**
114
**What is the maximum temperature of baseboard fin tube radiators**
**160°f**
115
**If you have water in the blower assembly you most likely have?**
**Leaking secondary heat exchanger**
116
**Heat exchangers are designed to maintain a temperature rise of?**
**30-60°f**
117
**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*
118
**What type of heat exchanger is pictured?**
**Stainless steel self cleaning fire tube**
119
**What type of heat exchanger is pictured?**
**Brazed plate**
120
**What type of heat exchanger is pictured?**
**Shell and tube**
121
**Where do you often see shell and tube heat exchangers?**
**Pool heaters**
122
**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**
123
**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.*
124
**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*
125
**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.*
126
**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*
127
**Ideally your inducer amperage will be ____ than its rating?**
*higher/lower*
**lower**
128
**Inducer motors always have start capacitors?**
*True/False*
**False**
*Inducer motors have **run** capacitors*
129
**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.*
130
**Which wire should an ammeter be placed around?**
*Hot/Neutral/Ground*
**Neutral**
131
**What tool is used to measure the rotation speed of the motor shaft on a rooftop/package unit?**
**Tachometer**
132
**What are 3 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**
133
**What do you tell a customer when their inducer motor is failing/failed?**
**We need to replace the inducer motor because the inducer/combustion motor is the first component to start when your heat comes on. If it seizes up or fails the furnace cannot run and they are very specific (OEM) meaning if it fails suddenly it will have to be ordered in.**
134
**What do you offer aswell as 2 additional offers you can give a customer with a failed/failing inducer motor?**
**Offers:**
**1. Replace due to failure or replace preventatively**
*Additional offers:*
*1. Flush / clean drain*
*2. Burner cleaning / FP cleaning*
135
**What is the expected lifespan of an inducer motor?**
**Inducer should last 10 years depending on cycles, and other component failures. Bad HX and burners/blocked drains will destroy an inducer motor. This is why maintenance is so important.**
136
**What is the purpose of an inducer motor?**
**To induce a draft and expell flue products to the outside**
137
**What is the purpose of the pressure switch?**
**Monitors the heat exchanger pressures to ensure proper flow of combustion products to the outdoors**
138
**What is the "w.c rating of the pressure switch pictured?**
**-0.75"w.c**
139
**The pressure switch pictured will be --------- at a pressure of -0.2"w.c**
*open/closed*
**open**
140
**The pressure switch pictured will be ------- at a pressure of -1.0**
*open/closed*
**closed**
141
**What do you tell a customer when their pressure switch is failing/failed?**
**We NEED to replace the pressure switch because the pressure switches are a safety device. If they are not working or are out of calibration it is important to replace to prevent a sudden no heat situation.**
142
**What is the maximum temperature drop you can have across a filter drier?**
**3°f**
143
**How long should a pressure switch last?**
**Pressure switches should last 10 years depending on cycles, and other component failures. Blocked drains will destroy pressure switches from moisture. If moisture gets into pressure switches compomised. Maintenance is important to prevent blocked drains or flame sensing short cycling.**
144
**Transformers only work with direct current?**
*True/False*
**False**
*Transformers only work with **Alternating current***
145
**If my stepdown transform takes 120v at 5 amps down to 24v at 25 amps what is the VA rating?**
**600VA**
*120V x 5A = 600VA*
*24V x 25A = 600VA*
146
**What are 2 reasons for having a stepdown transformer to 24v in a furnace?**
**1. Cost of wire**
*It is cheaper to have 18awg 24v circuits than it is to have 14awg 120v circuits.*
**2. Safety of the person and the furnace**
*It is safer for the technician and customer to have circuits on 24v instead of 120v in the event of a short or power surge*
147
**In a step-up transformer the voltage between the primary and secondary** **----- and the current ------.**
*increases/decreases*
**Voltage increases**
**Current decreases**
148
**In a step-down transformer the voltage between the primary and secondary ----- and the current ------.**
*increases/decreases*
**Voltage decreases**
**Current increases**
149
**At depths of 3' and greater underground the temperature is always --°f.**
**55°f**
150
**How long should a transformer last before it must be replaced?**
**Transformers should last 10+ years depending on cycles, and other component failures. Water dripping from top cabinet from loose drain hoses etc will destroy transformers. Brownout, power surges etc.**
151
**What do you tell a customer when their transformer is failed/failing?**
**We need to replace the transformer because the transformer powers your control boards for both heating and cooling and only fails with a surge of electricity. It is important to install a transformer with a fuse in order to prevent any damage to control board!**
152
**If a transformers output voltage is 24v, there is 100 turns on the secondary winding, and 1000 turns on the primary winding, what is the input voltage?**
**240v**
*Output voltage x number of primary windings ÷ number of seconday windings*
*24v x 1000 ÷ 100*
153
**If a transformer input voltage is 120v, there is 500 turns on the primary winding, and 100 turns on the secondary winding, what is the output voltage?**
**24v**
*Input voltage x number of secondary windings ÷ number of primary windings*
*120 x 100 ÷ 500*
154
**In a step ------- transformer there are more windings on the primary side than there are on the secondary side.**
*up/down*
**Step-down**
155
**What is the purpose of the control board?**
**Controls the function and safety of the equipment.**
156
**How long should a control board last in your equipment?**
**Control boards should last 10 years depending on cycles, and other component failures. Water dripping from top cabinet from loose drain hoses etc will destroy control board. Brownouts power surges etc.**
157
**What do you tell a customer when their control board is failing/failed?**
**We need to replace the circuit board because the control board controls everything for both heating and cooling. If it fails the furnace or ac cannot run and they are very specific meaning if it fails suddenly it will have to be ordered in.**
158
**How can you tell the resistance rating of a resistor on a control board?**
**The colour and order of the rings around the resistor.**
159
**What is the purpose of the blower assembly?**
**Regulate the temperature of the heat exchangers**
*Moves the proper CFM across the heat exchangers and keeps everything within operational parameters*
160
**A PSC motor uses the equivalent to how many 60w lightbulbs of energy?**
**13**
161
**An ECM motor uses the equivalent to how many 80w lightbulbs of energy?**
**1**
162
**Why do the bearings on an ECM motor not leak as often as PSC motors?**
**Because ECM motors run cooler than PSC motors.**
163
**When a PSC motor has higher amperage than its rating the likely cause is...**
**The bearings are drying putting more strain on the motor.**
164
**ECM stands for..**
**Electrically commutated motor**
165
**PSC stands for..**
**Permanent split capacitor**
166
**What type of motor is required for a modulating system?**
**ECM**
167
**What is an internal overload and where is it found?**
**A normally closed contact found right behind the C terminal.**
168
**What is the epexcted lifespan of a blower assembly?**
**Life varies with filter quality and regular maintenance! Inspection reveals dirty blower wheels, oily motors etc.**
169
**How do we explain to a customer that their blower assembly is failing/failed and needs to be cleaned/replaced?**
**We need to clean or replace the blower wheel/motor because we must move enough air! A bad blower wheel or seizing motor will drastically reduce efficiency and can overheat your exchanger causing irreparable damage! During cooling it will flood refrigerant back to your compressor and can cause compressor failure.**
170
**What are 2 additional items/services we can offer with a blower assembling cleaning/replacement?**
**Additional offers:**
*1. Install 5" filter cabinet*
*2. Evaporator coil cleaning*
171
**Which part of the motor is "A" pointing towards in the image below**
**Rotor**
172
**Which part of the motor is "B" pointing towards in the image below**
**Stator**
173
**Which part of the motor is "C" pointing towards in the image below**
**Ball Bearing**
174
**Which part of the motor is "D" pointing towards in the image below**
**Shaft**
175
**Which part of the motor is "E" pointing towards in the image below**
**Control module**
176
**What type of bearings are used in ECM motors?**
**Ball bearings**
177
**For optimal dew point we want to keep our evaporator between --°f and --°f.**
**35°f and 45°f**
178
**High amounts of VOC (volatile organic compounds) are more frequent in modern households which corrode copper coils. This is called?**
**Formicary corrosion**
179
**Due to formicary corrosion on copper evaporator coils, companies have transitioned to making coils out of ------.**
**Aluminum**
180
**What kind of circulating pump must you use on a domestic water line**
**Brass**
181
**Evaporator coils should be disinfected every...**
**4 years**
182
**Capacitors are measured in...**
**µf (micro-farads)**
183
**What are 2 ways you can test a capacitor for signs of failing/failure**
**1. Electrically**
*Testing µf from C to Herm and C to Fan to ensure the capacitor is within its ratings*
**2. Visually**
*Contacts are rusting*
*The lid is bubbling*
*The capacitor is swelling*
184
**If the condensor coil is plugged does that affect the capacitor?** *If yes, how?*
**Yes,** *If the condensor coil is plugged both the fan motor and compressor will draw high amounts of amperage which will put to much demand on the capacitor which will result in failure of the capacitor.*
185
**How much additional torque does a super boost provide?**
**300%**
186
**A manual disconnect switch must have how many feet of service clearance?**
**3'**
187
**How often should capacitors be replaced?**
**Capacitors are like a battery and when everything is operating correctly they can last over 10 years. Maintenance is KEY as high head pressure, short cycling, etc. can cause the cap to swell and eventually do damage to major components.. The "made in china caps" are designed for 5 years.**
188
**How often should a compressor be replaced?**
**Compressor should last a lifetime. High amps, weak windings, and damaged valves are all due to neglect and lack of maintenance**
189
**What happens when the compressors oil gets burnt?**
**The burnt oil mixes with the refrigerant and becomes acidic. Once it becomes acidic the entire system is contaminated.**
190
**What is the purpose of the resistor in the start capacitor?**
**To discharge the capacitor when powered down.**
191
**In the diagram of a PSC below, what does "A" represent?**
**Internal overload**
192
**In the diagram of a PSC below, what is the winding between "B and C" called?**
**Run winding**
193
**In the diagram of a PSC below, what is the winding between "B and D" called?**
**Start winding**
194
**In the diagram of a PSC below, what does "E" represent?**
**Run capacitor**
195
**In the diagram below, is the resistance higher between *B and C* or between *B and D*?**
**B and D**
*The start winding has more windings to create a stronger magnetic field giving it a higher resistance.*
196
**In the diagram below, between which two points will you have the highest resistance?**
**C and D**
*The current must travel through both the run winding aswell as the start winding to get from point C to D giving it the highest resistance.*
197
**How often should you have to replace/repair a condensor fan motor?**
**Life varies with maintenance if the coil is plugged and the motor is over amping trying to draw air through the coil it may overheat or prematurely seize up.**
198
**What do you tell a customer when they need to replace their compressor due to it failing?**
**We need to replace the compressor because a compressor failure is a major repair and if caused by burnout the entire ac system is compromised. It is strongly recommended that new equipment is considered. Replacement compressors caused by low refrigerant burnout will not have warranty**
199
**What do you tell a customer when their condensor fan motor needs to be repaired/replaced?**
**We need to clean or replace condenser fan motor because a bad or worn condenser fan motor drastically reduces efficiency and can overheat your condenser causing very high pressures!**
200
**Can contactors withstand more amperage than a relay?**
**Yes**
201
**How are contactors powered?**
**Contactors are powered by 24v through Y and returning through C**
202
**What happens if there if voltage drop present across a contactor?**
**If the paths are bad and there is voltage drop in the contactor than the motors will be running very rough on an imbalance of power which will cause damage**
203
Why do we mix glycol with water
price
viscosity
to prevent lines from freezing
204
# S
**What is the standing pressure in an expansion tank?**
**12-15psi**
205
**What are the 4 moving parts on an IBC tankless water heater**
**1. Combustion fan**
**2. Mixing valve**
**3. Gas valve**
**4. Damper**
206
**How many GPM can an IBC tankless water heater move at 70°F temp rise?**
**5.2 GPM**
207
**What is the approximate city water pressure coming into a residential home?**
**60psi**
208
**What is the turndown ratio for a VX boiler system?**
**6.5:1**
209
**What is the turndown ratio for a CX boiler system?**
**10:1**
210
**You can run an ERV in the summer.**
*True/False*
**True**
211
**You can run an HRV in the summer.**
*True/False*
**False**
212
