Hydronic Heating and Cooling Chapter 3

The most commonly used heat source in hydronic systems is the boiler, which has many forms.

True

Fuel oil burners atomize fuel oil to increase contact with combustion air for maximum combustion efficiency.

True

The steel boiler ranges from 50,000 Buh to a maximum of 100,000 Btuh.

False

In a system with a natural-draft boiler, the amount of natural draft produced decreases with the height of the flue.

False

Tankless boilers heat HTF as it flows through the heat exchanger.

True

A heat pump can operate only in heating mode.

False

A relief valve is an automatic pressure relieving device actuated by the static pressure upstream of the valve, and it opens further with the increase in pressure over the opening pressure.

True

A low-water cut-off is a device that is designed to monitor the water level in a boiler and to signal the boiler burner to shut down if the water level rises above the safe level of the boiler.

False

A pressure-reducing valve must be installed with the arrow on the body pointing in the direction of flow.

True

A reduced pressure principle backflow prevention assembly is a backflow preventer consisting of three independently acting internally spring-loaded check valves, a differential pressure-relief valve, three properly located test cocks, and three isolation valves.

False

A circulating pump cannot be the main pump in a hydronic system.

False

The most commonly used cooling terminal unit uses a fan to blow the room air over a coil through which chilled HTF is circulated.

True

As evaporator-to-condenser pressure differential increases, compressor work heat decreases in relation to evaporator cooling ability.

False

A compression stroke is the movement of a piston in a cylinder that causes the volume of the cylinder to increase, which rapidly decreases the pressure.

False

Heat absorption occurs at a low temperature and pressure, and is known as the low pressure side of a refrigeration system.

True

A forced-draft cooling tower is a cooling tower in which fans are located in the airstream, typically at the top of the tower, in order to force the ambient air through.

True

Refrigerants typically have a high boiling point.

False

Single-wall heat exchangers are less efficient than double-wall heat exchangers of equal size.

False

In a plate heat exchanger, heat passes very easily through the thin wall separating the two media from each other.

True

The most frequent cause of nonperformance in heat exchangers is improper venting and fouling.

True

A(n)____ burner consists of a forced air fan that is used to bring air under pressure into close contact with the fuel.

Power

The boiler is considered _____ if the combustion chamber is mounted below the HTF.

Dry based

_____ boilers are normally water-tube boilers that use a configuration of finned tubes with headers as the heat exchanger.

Copper

_____ draft is mechanical draft from air pulled through the boiler combustion chamber with fans located in the breeching.

Induced

Flue temperatures are required to be at least 250°F to prevent _____ in the flue.

Condensation

A condensing boiler is a boiler where the heat exchangers are designed to extract _____ heat from the water vapor found in hot combustion gases before the gases enter the flue.

Latent

A _____ is a mechanical compression refrigeration system that reverses the flow of refrigerant through a system to transfer heat from one area to another.

Heat pump

A(n) _____ is a device that controls the starting, stopping, and firing rate of a hot water boiler burner by measuring the temperature of the water in the boiler.

Aquastat

The average low pressure water boiler is constructed for a maximum working pressure of _____ psig.

30

A _____ utilizes a paddle to sense fluid flow and physically close an electrical circuit, allowing power to the boiler burner.

Flow switch

The atmospheric vent in a backflow preventer is required to open under a backflow pressure condition when the supply pressure is no less than _____% of the downstream pressure.

20

A compression tank is a thermal expansion and air capture component that performs _____ important functions in a hydronic heating system.

Four

A _____ is a high-volume hydronic air conditioning device that cools circulating HTF for terminal unit use.

Chiller

The hydronic cooling cycle is composed of _____ separate and distinct cycles that create the complete hydronic cooling system.

Five

The _____ is the part of a mechanical refrigerating system that receives the refrigerant vapor at low pressure and compresses it into a lower volume at a higher pressure.

Compressor

The _____ compressor consists of a motor-driven shaft that turns a plate with a spiral of metal on it.

Scroll

A _____ is a device used to reject heat from the water circulated through a building's water-loop system or chiller condenser.

Cooling tower

A _____ cooling system uses water's cooling capacity a single time.

Once through

A _____ cooling tower is a cooling tower in which the water and ambient air are Introduced at the top of the tower and flow downward through the fill.

Parallel flow

The _____ is the reservoir located above a cooling tower to hold heated water prior to its flow through the fill.

Distribution basin

A (n) _____ heat exchanger is a heat exchanger that is located in a thermal storage tank and allows the transfer of heat from one HTF to the other without permitting the two liquids to mix.

Internal

A _____ heat exchanger is an external tube-type heat exchanger that consists of a large pressure vessel with multiple tubes that run through it.

Shell and Tube

A pressure vessel is a tank or container that operates at a _____ greater than atmospheric pressure.

Pressure

A(n) _____ uses a series of copper rods enclosed in waterproof tubes surrounded by water to provide heating by electricity.

Immersion heater

A(n) _____ boiler, a variation of the fire-tube boiler, utilizes a central fluid backed cylindrical combustion chamber surrounded by fire tubes accommodating two or more flue gas passes.

Scotch Marine

The _____ system is that part of a boiler that regulates the flow of air to and from the boiler fuel burner.

Boiler draft

According to manufacturers, the operating efficiency of _____ boilers can be as high as 98%.

Condensing

A(n) _____ is the amount of heat produced by a boiler as fuel is burned and is expressed in British thermal units per hour (Btuh).

Input rating

Solar water heating utilizes the portion of the solar radiation spectrum referred to as _____ to create heat energy.

Sunlight

Whenever the temperature in a boiler is above 212°F and the _____ discharges, the sudden pressure drop causes the higher temperature water to flash to steam.

Relief valve

Air control boiler fittings are selected on the basis of the _____ supply main size.

Trunk

_____ and mounting method are the two main factors in selecting a low-water cut-off.

Boiler pressure

The _____ to a boiler is the cold water supply to the boiler that is used for boiler filling.

Make up water line

Backflow prevention involves the selection and installation of an approved backflow preventer designed to prevent backflow into a (n) _____ water supply.

Potable

A (a) _____ contains either a bladder or a diaphragm to separate the air charge contained in the tank from the system HTF.

Precharged expansion tank

The _____ pumps the vaporized refrigerant away from the evaporator and discharges it at a higher pressure and temperature into the condenser.

Compressor

_____ is the reverse of boiling.

Condensation

_____ compressors compress refrigerant vapor by moving a piston up and down inside of a cylinder.

Reciprocating

_____ vane compressor is a type of rotary compressor that rotor to which the vanes are attached.

Stationary

A _____ cooling tower is a cooling tower with open water loops, allowing direct contact between circulating water and outside air.

Wet

_____ is the temperature difference between cooling water leaving a cooling tower and the wet-bulb temperature of air entering the tower.

Approach

The _____ on any closed piping circuit will dictate, by its location, the system pressure changes that will occur when the pump starts.

Compression tank

The purpose of renewable, sacrificial anodes present on some exchangers is to provide _____ in order to inhibit electrolytic corrosion.

Cathodic protection

A (n) _____ plate heat exchanger is sometimes referred to as a “honeycomb" or “turboseal-type" plate exchanger.

Brazed