1.A hydronic heating system operating above 250°F requires:
- A.Standard plumbing materials
- B.Materials and installation per ASME B31.1 or B31.9 pressure piping codes✓
- C.PVC piping
- D.No special requirements
Why: High-temperature hot water (HTHW) systems operate above atmospheric boiling point under pressure. They require pressure-rated materials, safety relief devices, and code-compliant installation.
2.A glycol system requires what additional considerations versus plain water?
- A.None
- B.Larger pump, expansion tank sizing, compatible seals/gaskets, and corrosion inhibitor maintenance✓
- C.Smaller pipes
- D.No expansion tank
Why: Glycol: more viscous (larger pump/motor), lower heat capacity (higher flow rates), requires compatible seals (some rubbers swell), and corrosion inhibitors must be monitored and maintained.
3.A pressure-independent control valve (PICV) provides:
- A.Only on/off control
- B.Constant flow regardless of system pressure fluctuations — combining balancing and control in one valve✓
- C.Only manual adjustment
- D.Only pressure control
Why: PICVs maintain set flow rate regardless of pressure changes in the system. They eliminate the need for separate balancing valves and simplify system commissioning.
4.A check valve in a hydronic system prevents:
- A.Forward flow
- B.Reverse flow that could cause pump damage or unwanted circulation between zones✓
- C.Pressure buildup
- D.Temperature change
Why: Check valves: prevent reverse flow during pump shutdown, prevent thermosiphoning (unwanted gravity circulation), and protect pumps from backflow. Spring-loaded or swing type.
5.A double-wall heat exchanger is required when:
- A.Always
- B.One fluid is potable water and the other is a potentially hazardous fluid (glycol, refrigerant, chemicals)✓
- C.Never
- D.Only for steam
Why: Double-wall heat exchangers prevent cross-contamination if a leak occurs. Required by code when potable water could be contaminated by a non-potable fluid in the other circuit.
6.A BTU meter measures:
- A.Only temperature
- B.Energy transfer: flow rate × temperature difference between supply and return = BTU/hour✓
- C.Only flow
- D.Only pressure
Why: BTU meters calculate: Q = flow × ΔT × constant. They measure both flow rate and temperature differential, computing actual energy delivered to or removed from a zone. Used for tenant billing.
7.A chemical feed system on a hydronic loop maintains:
- A.Only temperature
- B.Proper water chemistry (pH, inhibitor levels, biocide) to prevent corrosion and biological growth✓
- C.Only pressure
- D.Only flow
Why: Chemical treatment: maintains pH 8-10 (reduces corrosion), oxygen scavenger (prevents pitting), biocide (prevents bacterial growth), and corrosion inhibitor. Regular testing is essential.
8.When brazing copper refrigeration pipe, the flame should be:
- A.Oxidizing
- B.Neutral to slightly reducing to prevent copper oxidation✓
- C.Carburizing only
- D.Maximum heat
Why: Slight excess acetylene (reducing flame) prevents copper oxidation. Oxidizing flame causes scale that weakens the joint. Use silver brazing alloy with appropriate flux for dissimilar metals.
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