True / False 4B Midterm

Although Schrader gauges are just as accurate as Bourdon tube gauges, they receive more damage from pressure surges

False

Comfort is achieved by supplying heat to the body

False

Forced-Air systems cost less than hydronic systems to operate and maintain because of the durability and long life of the equipment

False

Hydronic heating systems can not be used to melt snow

False

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

False

Pressure drop, head pressure and static pressure are all the same thing

False

Pumps or circulators are designed to operate witha mixture of air and water

False

The gases that make up air cannot exist while dissolved in water or other HTFs

False

Thermistor thermometers are not suitable for lower temperature rangers

False

all piping expands when cooled and contracts when heated

False

at elevated system water temperatures, a lower cold fill pressure could be necessary to properly pressurize a system

False

bull-head conections should be used on the return piping of divided circuits to the heat source

False

flow in the main of a series loop system will not e affected by reducing or stopping flow in individual terminal units

False

in a one-pipe system, the supply connection to the terminal unit must be downstream from the retunr connection

False

in a reverse-return system, the first terminal unit take off the supply main is the first to connect to the return main

False

swing check valves use a spring and disc to prevent reverse flow of a fluid

False

the termperature of a secondary loop HTF is not sufficient to provide the proper heat transfer needed for the terminal unit supplied by the tertiary loop

False

TEL is the sum of all the straight lengths of pipe plus 40%

False ;

the human body at rest, loses heat at a rate of 420 BTUh

False ; 400 BTU per hour

Sensible heat is the heat applied to or removed from a substance that results in a change of state

False ; Latent Heat

Forced convection occurs because of a combination of heat transfer by conduction and heat transfer by actual movement of some of the fluid from one place to another

False ; Natural Convection does this

the best location for air separator is a point that has both the lowest temperature and the highest pressure

False ; highest temp and lowest pressure

A gauge pressure range shoudl be selected so the pressures to be measured fall in the higher two-thirds of the scale range

False ; should be in the middle range

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 about the safe level of the boiler

False ; signals the boiler to shut down if the water level drops below the safe level of the boiler

Cross-linked polyethylene (PEX) is a material made up of molecules of low-densisity polyethylene that are temporarily linked to each other by a process called cross-linking

False ; they are permanently linked

in air control management systems, manual air vents are recommended to be installed at terminal units and high piping points

T

A float valve air vent uses and internal flow valve within the body of an air accumulator to automatically remove air from a hydronic system

True

A hydronic system is a heating and/or cooling system that uses water or another fluid as a heat transfer medium to move heat from one area to another

True

Comfort is a condition in which the human body feels neither warm nor cool

True

Comfort is achieved by controlling the rate and manner in which heat is transferred from the body.

True

Domestic hot water can be heated using the same boiler that supplies the hydronic system. The three ways this can be done are with a combination boiler, a heat exchanger, or an indirect fired hot water heater

True

During seismic activity, improperly supported piping can fall or sway out of a support system

True

Each time water is added to a hydronic system, additional aire enters the system as entrained air and dissolved gases

True

General piping layout should be as simple as possible

True

In most installations, the flow-control valve replaces the first 90 elvbow in the supply main with an angle pattern valve

True

Radiant hydronic heating is cleaner than forced aire systems because the HTF is confined in pipes and cannot carry dirt or odors from room to room

True

The amount of heat in British thermal units required to change the temperature of one pound of a substance one degree Fahrenheit is called the specific heat of that substance

True

The human body loses heat by radiation (47%), conduction and convection (30%), and evaporation (23%)

True

The most commonly used heat source in hydronic systems is the boiler

True

The objective of any building heating or cooling system, including a hydronic system, is to provide the maximum human comfort possible

True

Triple Duty Valves are quietly operating heavy-duty valves that perform all the functions normally required on the discharge side of hydronic system pumps

True

Zoning is particularly important in multilevel homes and large buildings

True

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

True

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 secondary circuit or loop is a separate pipin configuration connected to the primary loop and supplies HTF to separate heat transfer loads or terminal units

True

in a direct return system, starting at the boiler, the first terminal unit taken off the supply main is the first to connection to the return main .

True

in a plate heat exchanger, heat passes bery easily through the thin wall separating the two media from each other

True

in a single main system, if proper air control equipment is installed at the heat source, further venting should not be necessary

True

in an automatic changeover system, the tees that connect the chiller or boiler to the system piping are placed as close together as possible to keep the pressure drop between them to a minimum

True

in two-pipe systems, the size of the main is reduced as branches are taken off the main

True

pre-charged expansion tanks are designed to absorb the force of thermal expansion in hydronic heating and cooling systems

True

the most frequent cause of nonperformance in heat exchanges is improper venting and fouling

True

the two types of one-pipe systems are the series loop system and the single main system

True

thre-way valves may be manually, electronically, pneumatically, or thermally controlled

True

water speeds of 2.5-8 fps are generally accepted from hydronic systems

True

whenever the temperatur is a boiler is above 212F and the relief valve discharges, the sudden pressure drop cause the higher temperature water to flash to steam

True

where unit heaters comprise either all or part of the heating units in a hydronic system, it is generally recommended that they be installed on a two-pipe system rather than a one-pipe system

True