Chapter 9 - Quiz

For current-generation hydronic heating systems, the controlled variable is usually indoor air temperature.

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.

Heat output from the heat emitter occurs whenever the supply water temperature equals the room air temperature.

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.

Most heat source reset controllers have an adjustable minimum supply temperature.

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.

There are hydronic heating applications where control action is required based on the difference between two temperatures rather than the value of either temperature.

A multizone relay center is designed to isolate the wiring and control operation of several independent zone circulators or zone valves.

One purpose of mixing is to protect conventional boilers from operating at conditions that allow sustained flue gas condensation.

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.

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 __________.

The term __________ differential refers to the actual variation in the controlled variable as the system operates.

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 __________.

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.

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.

__________ 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.

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.

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.

The term injection mixing applies to any mixing assembly in which __________ is pushed (e.g., injected) into a circulating distribution system.

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.