CSLB General Building (B) Trade Practice Test
常见问题
这里有多少道 CSLB HVAC (C-20) Trade 练习题?+
一整套原创 CSLB HVAC (C-20) Trade 练习题,覆盖官方内容板块、按真实考试权重分布、附解析。免费,无需注册。
CSLB HVAC (C-20) Trade 考试是什么样的?+
大约 100 道题、210 分钟、需 72% 及格。先在这里按主题刷题,再做完整计时模考检验准备度。
这些是真实考题吗?+
不是。每道题都是 100% 原创,依据公开一手来源编写并附解析。我们从不抄袭真题或付费备考资料。
我可以用中文或西班牙语学吗?+
PrepPass 练习提供英文、中文、西班牙文。官方考试以英文进行 —— 你随时可以把题目语言切回英文,熟悉考试当天的确切术语。
样题与解析
以下是本题库中的部分真题与完整解析。完整题库请用上方的刷题工具。
- 1. Load & Design
In residential load calculations, what does an ACCA Manual J procedure primarily determine?
- a.The size and gauge of supply ductwork
- b.The heating and cooling loads of a building based on its construction and climate
- c.The refrigerant charge required for the condenser
- d.The electrical service size for the panel
答案: b
解析: Manual J is the industry-standard residential load calculation method. It estimates the sensible and latent heating and cooling loads by accounting for construction, insulation, windows, orientation, infiltration, and local design temperatures. Equipment is then selected to match those calculated loads.
依据: California Energy Code (Title 24)
- 2. Load & Design
Under the California Mechanical Code, when is a permit generally required for HVAC work?
- a.Only for commercial buildings
- b.Only when replacing a thermostat
- c.When installing, altering, or replacing mechanical equipment such as a furnace or air conditioner
- d.Never for residential work
答案: c
解析: The CMC and local jurisdictions require a mechanical permit for installing, altering, or replacing regulated equipment like furnaces, air conditioners, and ductwork. Permits trigger inspection to verify code-compliant, safe installation. Minor maintenance such as filter changes does not require a permit.
依据: 2022 California Mechanical Code (CMC)
- 3. Installation
What is the primary purpose of providing combustion air to a gas-fired furnace?
- a.To cool the electronic controls
- b.To supply oxygen for complete and safe fuel combustion
- c.To increase supply air temperature
- d.To reduce refrigerant pressure
答案: b
解析: A gas furnace needs adequate combustion air so the burner receives enough oxygen for complete combustion. Insufficient air causes incomplete combustion, producing carbon monoxide and sooting. The CMC specifies required openings or ducts based on the appliance input and the confining space.
依据: 2022 California Mechanical Code (CMC)
- 4. Installation
In a split-system heat pump, the outdoor coil functions as the condenser during which mode?
- a.Heating mode
- b.Defrost mode
- c.Cooling mode
- d.Emergency heat mode
答案: c
解析: In cooling mode the outdoor coil rejects heat and acts as the condenser, while the indoor coil absorbs heat as the evaporator. In heating mode the reversing valve swaps these roles. Understanding this reversal is key to installing and servicing heat pumps.
- 5. Installation
The condensate drain line from a cooling coil is often fitted with a trap to accomplish what?
- a.Add refrigerant
- b.Prevent air from being pulled through the drain and allow proper condensate flow
- c.Increase blower speed
- d.Filter the return air
答案: b
解析: A properly sized trap on a draw-through coil prevents the blower's negative pressure from either holding water in the pan or pulling air backward through the drain. This allows condensate to flow freely to the drain. The trap depth is based on the unit's static pressure.
- 6. Refrigeration
A thermostatic expansion valve (TXV) controls refrigerant flow into the evaporator to maintain what?
- a.Constant condenser pressure
- b.Constant compressor speed
- c.A relatively constant evaporator superheat
- d.Constant subcooling
答案: c
解析: A TXV modulates refrigerant flow to hold a stable superheat at the evaporator outlet, matching flow to the load. This keeps the coil fed efficiently and protects the compressor from liquid floodback. It responds to the temperature and pressure of the suction line.
- 7. Refrigeration
As a general principle, adding refrigerant charge to a properly running system tends to do what to the low-side pressure?
- a.Lower it significantly
- b.Raise it
- c.Have no effect
- d.Reverse compressor rotation
答案: b
解析: Adding charge generally raises system pressures, including the suction (low-side) pressure, while removing charge lowers them. Technicians interpret these trends together with superheat and subcooling. Charging must be verified against manufacturer targets, not pressure alone.
- 8. Service & Troubleshooting
A typical low-voltage control (thermostat) circuit in residential HVAC operates at what voltage?
- a.120 volts
- b.240 volts
- c.24 volts
- d.480 volts
答案: c
解析: Residential control circuits generally operate at 24 volts AC, supplied by a step-down transformer. The thermostat switches this low voltage to energize relays and contactors. Measuring 24 volts at the appropriate terminals helps confirm control-circuit operation.
- 9. Service & Troubleshooting
A technician measuring compressor amp draw far above the rated load amps (RLA) should suspect what?
- a.A perfectly healthy compressor
- b.A mechanical or electrical problem such as high head pressure or failing windings
- c.An oversized filter
- d.Low thermostat voltage
答案: b
解析: Amp draw well above the nameplate RLA indicates the compressor is overloaded, which can stem from high head pressure, low voltage, or degrading windings. Continued operation risks overheating and failure. The technician investigates head pressure, voltage, and mechanical condition.
- 10. Safety & Codes
The California Mechanical Code (CMC) primarily governs what?
- a.Electrical wiring only
- b.Plumbing fixtures only
- c.The installation of heating, ventilation, air-conditioning, and refrigeration systems
- d.Structural framing
答案: c
解析: The CMC sets the rules for installing mechanical systems including furnaces, air conditioners, ventilation, and refrigeration, covering venting, combustion air, clearances, and equipment access. Electrical work falls under the CEC and plumbing under the CPC. Contractors coordinate across these codes.
依据: 2022 California Mechanical Code (CMC)