Steam Fitting Contractor Exam

CA C4 Boiler Hot Water Heating And Steam Fitting Contractor Exam Questions And Correct Answers (Verified Answers) Plus Rationale2026 Q&A| Instant Download Pdf

• Which type of boiler is most commonly used for residential hot water

heating?

• Fire-tube boiler
• Water-tube boiler
• Electric boiler
• Packaged boiler

Rationale: Water-tube boilers are commonly used for hot water and

steam systems because they can handle higher pressures and provide more efficient heat transfer.

• What is the primary purpose of a boiler relief valve?
• Increase boiler efficiency
• Prevent overpressure
• Circulate water
• Heat the water

Rationale: Relief valves are safety devices designed to prevent the

boiler from exceeding safe pressure limits.

• Which of the following fuels is NOT commonly used in boiler

systems?

• Natural gas
• Oil
• Diesel fuel
• Electricity 1 / 3

Rationale: Diesel fuel is rarely used in boilers; common fuels include

natural gas, oil, coal, and electricity.

• In a steam heating system, what is the main purpose of the steam trap?
• Increase steam pressure
• Prevent scaling
• Remove condensate
• Add chemicals

Rationale: Steam traps remove condensate from steam lines without

allowing steam to escape.

• What is the typical operating pressure range for residential hot water

boilers?

• 0–10 psi
• 12–30 psi
• 40–60 psi
• 100–150 psi

Rationale: Residential hot water systems usually operate between 12–

30 psi to maintain safe and efficient heating.

• Which type of boiler is considered “high-pressure”?
• Residential water boiler
• Low-pressure steam boiler
• Industrial steam boiler
• Electric hot water boiler

Rationale: High-pressure boilers operate above 15 psi for steam and

above 160 psi for hot water, typical in industrial applications.

• What is the purpose of a boiler feedwater pump?
• Remove sludge
• Vent steam
• Supply water to the boiler
• Maintain temperature

Rationale: Feedwater pumps are used to supply water to the boiler to

replace water converted into steam.

• Which device measures water level in a boiler?
• Thermocouple
• Pressure gauge
• Sight glass
• Flow meter 2 / 3

Rationale: A sight glass allows operators to visually monitor water

levels in the boiler.

• What type of expansion tank is used in closed hot water heating

systems?

• Open tank
• Diaphragm or bladder tank
• Overflow tank
• Condensate tank

Rationale: Closed systems use diaphragm or bladder-type expansion

tanks to accommodate water expansion as it heats.

• What is “scale” in a boiler system?
• Rust buildup
• Mineral deposits
• Air bubbles
• Steam condensate

Rationale: Scale forms from minerals in the water that precipitate

when heated, reducing efficiency and potentially causing damage.

• Which chemical is commonly used to prevent corrosion in boiler

systems?

• Sodium hydroxide
• Sodium phosphate
• Sulfuric acid
• Chlorine

Rationale: Sodium phosphate helps control pH and prevents

corrosion in hot water and steam systems.

• What is the purpose of a low-water cutoff device?
• Increase boiler pressure
• Add chemicals automatically
• Shut off the burner if water level is too low
• Measure fuel efficiency

Rationale: Low-water cutoffs prevent the boiler from operating

without sufficient water, which could cause overheating or failure.

• Which of the following is a common cause of boiler explosion?
• Low fuel cost
• Low water level
• Proper venting
• Regular maintenance
• / 3