Week 1: Modern Refrigeration Ch 39

A hydronic heating system's ____ is designed to cope with the heat-related expansion of water. Select one: a. expansion tank b. flexible joints c. risers d. pressure-reducing valve

A

Chemicals that form a protective coating on the surface of the metal are ____. Select one: a. corrosion inhibitors b. scale-formers c. glycol solutions d. chemical scavengers

A

Chemicals that interact chemically with contaminants, rendering them inert are ____. Select one: a. chemical scavengers b. glycol solutions c. corrosion inhibitors d. scale-formers

A

If a hydronic system is providing uneven heating, a technician should check ____. Select one: a. All of the above. b. the operation of zone valves c. the operation of circulating pumps d. for air blockages

A

If a radiator in a steam heating system is cool while the others are hot because its valve is closed, it means the ____. Select one: a. thermostat for the valve is not working b. water level is too low c. steam trap is not working d. air vent is not working

A

The type of air that consists of small air bubbles that travel along with the circulating water is called ____ air. Select one: a. entrained b. free c. bubble d. dissolved

A

The water in a hydronic heating system should have a pH level between ____. Select one: a. 7 and 10 b. 1 and 4 c. 2 and 5 d. 10 and 12

A

To add pressure to an expansion tank, a(n) ____ should be used. Select one: a. bicycle pump b. refrigerant cylinder c. All of the above. d. vacuum pump

A

Water returning to a boiler should be about ____ lower in temperature than water leaving the boiler. Select one: a. 20°F (11°C) b. 5°F (3°C) c. 40°F (22°C) d. 10°F (6°C)

A

Which of the following statements about air vents in a hydronic system is false? Select one: a. They are installed at low points in a system where pockets of air are likely to form. b. None of the above. c. As air escapes the float chamber, water refills the float chamber, closing the valve. d. As air collects in the float chamber, the float drops, opening the valve to let air escape.

A

Which of the following statements about low-water cutoffs is false? Select one: a. They may operate a flow switch to cutoff water circulation. b. They may malfunction from foam caused by contaminants or air. c. They may be float-operated devices. d. They may operate a makeup water valve to add more water to a system.

A

Which of the following systems is designed so all of the circulating water passes through each component in the system? Select one: a. Series loop hydronic system. b. Two-pipe hydronic system. c. One-pipe hydronic system. d. Reverse return hydronic system.

A

A 100¢ length of steel pipe lengthens by ____ with every 100°F increase in temperature. Select one: a. 1 mm b. 1 inch c. 1 cm d. 1 foot

B

A control used to adjust boiler temperature to match the heating load by monitoring the cycle time required to satisfy a call for heat is a(n) ____. Select one: a. outdoor reset control b. indoor reset control c. aquastat d. tridicator

B

A valve that adjusts the water flow to each terminal unit or zone in a system so that heat is evenly distributed is called a ____ valve. Select one: a. thermostatic mixing b. balancing c. pressure-reducing d. flow-control

B

A valve that blends hot water from one inlet with cooler water from another inlet is called a ____ valve. Select one: a. balancing b. mixing c. pressure-relief d. pressure-reducing

B

A(n) ____ measures the temperature of the boiler water and turns the burner or heating element on and off as needed to maintain the preset temperature. Select one: a. tridicator b. aquastat c. outdoor reset control d. indoor reset control

B

Conventional boilers typically operate at water temperatures above ____. Select one: a. 120°F (49°C) b. 140°F (60°C) c. 200°F (93°C) d. 80°F (27°C)

B

Embrittlement can be slowed by ____. Select one: a. adding sodium hydroxide to the water b. maintaining a low acidity in the water c. adding propylene glycol to the water d. increasing the water's oxygen content

B

In which of the following systems does the terminal unit farthest from the boiler have the longest length of supply piping, but the shortest length of return piping? Select one: a. None of the above. b. Reverse return hydronic system. c. Direct return hydronic system. d. One-pipe hydronic system.

B

Series loop systems ____. Select one: a. can be divided into two loops for improved efficiency b. All of the above. c. are typically equipped with baseboard terminal units d. require each successive terminal unit to be larger than the previous unit

B

The part of a circulating pump that spins and forces water through a hydronic system is called the ____. Select one: a. stator b. impeller c. piston d. scroll

B

The type of air that consists of bubbles that collect at the high points in a system is referred to as ____ air. Select one: a. entrained b. free c. released d. dissolved

B

When a circulating pump stops operating, ____. Select one: a. pressure-relief valves open to lower system pressure b. flow-control valves prevent water from migrating c. hot water migrates to lower points in the system d. zone valves prevent cold water from migrating to higher points in the system

B

Which of the following statements about oil-fired boilers is false? Select one: a. The combustion chamber is lined with refractory material. b. A pilot light ignites the atomized fuel spray. c. The fuel oil is pumped into the burner nozzle under pressure. d. Fuel oil is burned using a gun-type burner.

B

Valve installed in the makeup water line to prevent water from flowing into the water main

Backflow preventer

Valve that adjusts the water flow so that heat is evenly distributed throughout the system.

Balancing valve

A specialized check valve installed in the makeup water line that prevents water from flowing back into the water main is called a(n) ____. Select one: a. low-water cutoff b. pressure-relief valve c. backflow preventer d. pressure-reducing valve

C

A tridicator is used on an oil-fired boiler to indicate ____. Select one: a. circulating pump voltage and current b. fuel oil pressure and flame temperature c. water pressure and temperature d. flue pipe temperature and pressure

C

Different sized tubing in a hydronic system should be joined using a(n) ____. Select one: a. U-trap fitting b. crimp and braze technique c. eccentric reducer fitting d. steam trap

C

If an expansion tank is hot from top to bottom, the tank is ____. Select one: a. likely operating just fine b. in vacuum c. waterlogged d. completely filled with air

C

Most water circulation problems in a hydronic heating system result from ____ trapped in the system. Select one: a. glycol b. water c. air d. refrigerant

C

When bleeding a hydronic heating system, a technician should ____. Select one: a. open each bleed valve until only air emerges from the valve b. capture bleeding air into cylinders for later use c. locate, clean, and repair faulty air vents d. All of the above.

C

Which of the following statements about gas-fired boilers is false? Select one: a. An air break installed in the stack helps maintain a constant pressure in the combustion chamber. b. When gas is supplied to the burner, a pilot light or electronic ignition system ignites the burner. c. A high-limit control automatically drains water when water temperature or pressure gets too high. d. A high-limit control is attached to the warm water outlet of the boiler.

C

Boiler that is over 90% efficient.

Condensing boiler

Boiler that operates at water temperatures above 140°F.

Conventional boiler

Boiler that gets classified as low mass and low volume.

Copper boiler

A thermostatically operated valve that regulates the flow of heated water through a zone is called a(n) ____. Select one: a. mixing valve b. None of the above. c. balancing valve d. zone valve

D

The air-removal device that typically contains a wire mesh element to create a swirling motion in the circulating water is called a(n) ____. Select one: a. air scoop b. air blower c. air vent d. air separator

D

The implosion of bubbles in a hydronic system, which can cause damage to impellers and other components, is called ____. Select one: a. air-wear b. scavenge damage c. deaeration d. cavitation

D

Which of the following should not be done when performing oil-fired boiler inspection and maintenance? Select one: a. Inspect the heat exchanger for soot. b. Inspect and clean the flue. c. Check and tighten all electrical connections. d. Operate the flame detector controls by opening the fuel valve.

D

Boiler in which the area under the combustion chamber is dry.

Dry-based boiler

A boiler's water level in a steam heating system may be verified by using the system's petcocks. Select one: True False

False

A four-pipe hydronic system shares piping so that both the heating and cooling systems cannot function simultaneously. Select one: True False

False

Conventional boilers are more efficient than condensing boilers. Select one: True False

False

Excessive air bubbles in a hydronic heating system can cause deaeration. Select one: True False

False

Free air consists of small air bubbles that travel along with the circulating water. Select one: True False

False

In a one-pipe steam heating system, the thermostatic radiator valve should be installed on the supply side of the radiator. Select one: True False

False

Instantaneous boilers have a medium-sized tank that heats water only when heat is called for. Select one: True False

False

Modern radiant heating systems most often use copper water tubing. Select one: True False

False

Purging removes air from a localized area rather than the entire system. Select one: True False

False

Water at a lower pressure can hold more dissolved oxygen than water at a higher pressure. Select one: True False

False

Valve that prevents water from migrating when the circulating pump quits operating.

Flow-control valve

Boiler that heats water only when heat is called for.

Instantaneous boiler

Valve that blends hot water with cooler water.

Mixing valve

Valve installed in the makeup water line that is also called a feed valve

Pressure-reducing valve

A circulating pump must circulate water away from an expansion tank. Select one: True False

True

Air vents may be installed on top of air separators to vent the air separated by those devices. Select one: True False

True

Expansion tanks may use a bladder filled with water that is surrounded by air. Select one: True False

True

Glycol should not be used in hydronic systems with galvanized piping. Select one: True False

True

If the water flow in a hydronic system ceases, a flow switch shuts down the system. Select one: True False

True

In a radiant heating system, the loops of tubing warm the surfaces adjacent to them by conduction. Select one: True False

True

In hot-water hydronic systems, eccentric reducer fittings reduce the danger of air pockets forming where differently sized tubes are joined. Select one: True False

True

Local building codes typically require boiler systems to pass a post-installation pressure test before they can be put into service. Select one: True False

True

Of the two major glycol solutions used in boilers, propylene glycol is the less toxic and more environmentally friendly. Select one: True False

True

Some heating and cooling systems are designed to operate simultaneously, allowing some spaces to be warmed and others to be cooled at the same time. Select one: True False

True

Water at a colder temperature can hold more dissolved oxygen than water at a warmer temperature. Select one: True False

True

Boiler in which water surrounds the combustion area.

Wet-base boiler

Valve that regulates the flow of heated water through a zone based on an applied voltage signal.

Zone valve