Questão 1
Questão
For current-generation hydronic heating systems, the controlled variable is usually indoor air temperature.
Questão 2
Questão
Most of the closed-loop control systems used for hydronic heating continually seek to eliminate any error that exists between the target value and measured value of the controlled variable.
Questão 3
Questão
Heat output from the heat emitter occurs whenever the supply water temperature equals the room air temperature.
Questão 4
Questão
The combination of near-continuous circulation and very gradual changes in water temperature tends to maximize expansion noises from the distribution piping and heat emitters.
Questão 5
Questão
Most heat source reset controllers have an adjustable minimum supply temperature.
Questão 6
Questão
Relay contacts are designated as normally open, or normally closed. In this context, the word "normally" means when the coil of the relay is not energized.
Questão 7
Questão
There are hydronic heating applications where control action is required based on the difference between two temperatures rather than the value of either temperature.
Questão 8
Questão
A multizone relay center is designed to isolate the wiring and control operation of several independent zone circulators or zone valves.
Questão 9
Questão
One purpose of mixing is to protect conventional boilers from operating at conditions that allow sustained flue gas condensation.
Questão 10
Questão
Direct injection mixing, whether accomplished using a two-way valve or variable-speed pump as the injection control device, provides the highest temperature difference between the supply and return injection risers.
Questão 11
Questão
The proper documentation of control systems is essential if they are to be expediently serviced in the future. A universally accepted tool for such documentation is the __________.
Responda
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microprocessor
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ladder diagram
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designer spreadsheet
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flow chart
Questão 12
Questão
The term __________ differential refers to the actual variation in the controlled variable as the system operates.
Responda
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control
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modulating
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operating
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real-time
Questão 13
Questão
To provide accurate control under low-load conditions, the controlled device must be able to maintain stable flow at very low flow rates. Such a device is said to have good __________.
Responda
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modulation
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variability
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machining
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rangeability
Questão 14
Questão
As outdoor temperature increases, and the heating load decreases, the water temperature supplied to the heat emitters also decreases as does their heat output. This concept is called outdoor __________ control.
Responda
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temperature
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variable
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proportional
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reset
Questão 15
Questão
Switches and relays are classified according to their poles and throws. The number of __________ is the number of independent and simultaneous electrical paths through the switch.
Responda
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poles
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throws
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contacts
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wires
Questão 16
Questão
__________ control is a planned strategy for shedding (e.g., temporarily turning off) one or more loads when a specific condition is detected in the system.
Responda
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Error
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Priority
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Systemic
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Conditional
Questão 17
Questão
In addition to equal run time rotation, there are other operating options available for staged/modulating heat sources. They are called series staging/modulation, parallel staging/modulation, and __________ staging/modulation.
Responda
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proportional
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on/off
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multiple
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hybrid
Questão 18
Questão
Boiler protection is accomplished by __________ the rate of heat flow from the boiler into the distribution system whenever the boiler temperature approaches or falls below a specified minimum operating temperature.
Responda
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reducing
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resetting
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increasing
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stabilizing
Questão 19
Questão
The term injection mixing applies to any mixing assembly in which __________ is pushed (e.g., injected) into a circulating distribution system.
Responda
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coolant
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air
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hot water
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mercury
Questão 20
Questão
A network control system without Internet access requires a person to be present to interrogate or adjust the system. This is unnecessary with a(n) __________ networked control system.
Responda
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Web-enabled
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electronic
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electromechanical
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fuzzy logic