Self-Test B-4.2 Hydronic System Valves

Complete Self-Test B-4.2 and check your answers.

1. A boiler’s relief valve senses and reacts to what characteristic(s) of water?
   1. Pressure
   2. Temperature
   3. Temperature and pressure
   4. Pressure or vacuum

    

2. What is the purpose of balancing valves?
   1. Maintain the correct water-to-air mixture
   2. Ensure equal flow of water through each circuit
   3. Achieve the design flow for each heat transfer unit or circuit
   4. Ensure continuous flow in the system

    

3. What is the purpose of flow check valves?
   1. Balance flow
   2. Protect the potable water supply
   3. Stop thermal siphoning
   4. Isolate heat transfer units

    

4. Why is a differential pressure bypass used?
   1. Protects the boiler
   2. Ensures continuous flow
   3. Flushes the system
   4. Relieves high pressure from the radiators

    

5. What is the normal pressure setting on a feedwater or pressure-reducing valve for a residential hydronic system?
   1. 160–180 psig
   2. 68–72 psig
   3. 40–54 psig
   4. 12–20 psig

    

6. The feedwater valve should be located where in relation to the backflow preventer?
   1. Downstream of the backflow preventer
   2. Upstream of the backflow preventer
   3. Parallel to the backflow preventer
   4. On the opposite side of the piping as the backflow preventer

    

7. What is the purpose of a backflow preventer?
   1. Prevents thermal siphoning
   2. Creates continuous flow throughout the heating system
   3. Prevents contamination of the domestic water supply
   4. Creates positive pressure within the system

    

8. The backflow preventer, feedwater valve, isolation valves, and bypass all combine to form what part of the hydronic system?
   1. Zone of reduced pressure
   2. Makeup water line
   3. Thermal bypass loop
   4. Boiler bypass

    

9. Where should the pressure relief valve on a residential boiler be located?
   1. On the high point of the system piping
   2. Just downstream of the system circulator
   3. On the boiler
   4. On the return piping next to the purge valve

    

10. What does a purge valve purge?
    1. Water out of the system on initial filling
    2. Air out of the system on initial filling
    3. All impurities out of the system during operation
    4. Air out of the system during operation

     

11. Complete the following statement: “Balancing valves operate best when ____________ .”
    1. 25% open
    2. Between 25% and 50% open
    3. Between 50% and 100% open
    4. 100% open

Answer Key: Self-Test B-4.2 is on the next page.