Question 1

The electronically commutated motors and improved hydrodynamic design of current generation variable-speed pressure-regulated circulators provide wire-to-water efficiencies that are approximately double those of standard wet-rotor circulators with permanent split capacity.

Accepted Answer

The statement is true.

Question 2

Primary/secondary (P/S) piping is the only way to achieve hydraulic separation between simultaneously operating circulators.

Accepted Answer

Hydraulic separation can be achieved through various means, not just primary/secondary piping. Other methods include using low loss headers, hydraulic separators, or closely spaced tees.

Question 3

The diverse loads served by many modern residential and light commercial systems often dictate that the distribution system contains elements from ____ of the basic distribution systems discussed in this chapter.

Accepted Answer

The statement says "many modern residential and light commercial systems often dictate that the distribution system contains elements from two or more of the basic distribution systems discussed in this chapter." Therefore, option B is the best choice.

Question 4

The closely spaced tees connecting a secondary circuit to the primary circuit are ____ when air is being purged from the system.

Accepted Answer

Closely spaced tees can be counterproductive when purging air because they may not allow for proper flow and separation of air from the water, making it difficult to remove air from the system.

Question 5

The degree to which two operating circulators interact with each other depends on the head loss of the piping path they have in common.This piping path is called the ____ piping.

Accepted Answer

The common piping path is the term used to describe the piping that connects two operating circulators. The degree to which these circulators interact with each other depends on the head loss of this common piping path. Therefore, the correct answer is D) common.

Question 6

One approach that takes advantage of the flexibility of PEX or PEX-AL-PEX tubing is called a ____ distribution system.

Accepted Answer

A home run distribution system uses one dedicated line from the manifold to each fixture, eliminating the need for a main supply line that runs throughout the entire building. This is possible because PEX or PEX-AL-PEX tubing is flexible and easy to route. The other options (A, C, and D) are not commonly used terms in plumbing and are not relevant to a PEX distribution system.

Question 7

Given the surface area of their bodies, hydraulic separators should be insulated to minimize heat loss to their surroundings.

Accepted Answer

Hydraulic separators can lose heat to their surroundings due to their large surface area, so it is recommended to insulate them to minimize heat loss.

Question 8

Different rooms within a single zone (e.g., controlled by a single thermostat) and supplied with the same water temperature cannot be maintained at different temperatures by adjusting the flow rate through individual heat emitters.

Accepted Answer

Different rooms within a single zone can be maintained at different temperatures by adjusting the flow rate through individual heat emitters, even if they are supplied with the same water temperature. This is because the flow rate controls the amount of heat being delivered to each room, and adjusting it can result in different temperatures.

Question 9

If the heat emitters are connected in series, the system flow rate will pass through each heat emitter.If the heat emitters are connected in parallel, the flow rate through each heat emitter can be proportioned based on load using an equation.

Accepted Answer

When heat emitters are connected in parallel, the flow rate through each heat emitter can be controlled by adjusting the valves or using a balancing valve to proportion the flow based on load, which can be calculated through an equation. However, if the heat emitters are connected in series, the flow rate will remain the same through each emitter, resulting in an uneven heat distribution.

Question 10

When a circulator with the flat curve is used, the differential pressure across the circulator changes dramatically as zone circuits turn on and off.

Accepted Answer

When a circulator with a flat curve is used, the differential pressure remains relatively constant regardless of the number of zone circuits that are turned on or off.

Question 11

All hydronic systems, regardless of how they are designed or installed, attempt to simultaneously stabilize at two unique operating conditions called thermal equilibrium and ____ equilibrium.

Accepted Answer

The other options do not make sense in the context of hydronic systems. "Spatial equilibrium" does not have a clear definition in this context, "zoning equilibrium" is not a commonly used term, and "R-value equilibrium" is not a relevant term in the operation of hydronic systems. "Hydraulic equilibrium," on the other hand, refers to the balance of pressure and flow in the system and is a key factor in achieving optimal performance.

Question 12

In a technique known as ____, the designer repeatedly analyzes both the hydraulic and thermal performance of a system using "candidate" hardware options and operating conditions, until a combination is found that yields acceptable heat distribution.

Accepted Answer

The technique described involves repeated analysis and refinement, which is characteristic of an iterative approach. This allows for gradual improvement towards an optimal solution, rather than relying solely on chance (A), selecting from a limited pool (B), or eliminating options without refinement (C).

Question 13

The concept of ____ provides a means by which the electrical energy consumption of a distribution system, per unit of heat delivery capacity, can be calculated and compared.

Accepted Answer

The concept of distribution efficiency allows for a comparison of electrical energy consumption per unit of heat delivery capacity in a distribution system. Hydraulic separation refers to preventing mixing of water between different heating and cooling systems. Hydraulic equilibrium refers to a state where the pressure drop across the system is equal at all points. Thermal envelope refers to the insulation and other materials that comprise the building envelope, which affect the heat loss and gain of the building.

Question 14

If a fixed-speed circulator is selected, a differential pressure bypass valve should be installed to reduce the potential for flow noise when only one or two zones are active.

Accepted Answer

When only one or two zones are active, the flow rate through the system may be less than what the circulator is designed for, leading to potential flow noise. Installing a differential pressure bypass valve helps to maintain a consistent flow rate and reduce the noise. This is especially important for fixed-speed circulators, which do not have the ability to adjust their speed based on the system demand.

Question 15

Over the last two decades, many heating professionals have come to recognize the failure of PEX and PEX-AL-PEX tubing as universal piping materials for residential and light commercial hydronic systems.

Accepted Answer

PEX (cross-linked polyethylene) and PEX-AL-PEX (a composite of PEX and aluminum) tubing have gained popularity over the last two decades for their flexibility, durability, corrosion resistance, and ease of installation, making them widely accepted in residential and light commercial hydronic systems.

Question 16

Designers should think of hydraulic separation as a physical concept that must be accomplished as an all-or-nothing condition.

Accepted Answer

Hydraulic separation can be achieved to varying degrees based on the design and implementation, and it does not have to be an all-or-nothing condition. It involves managing flow dynamics to ensure that different circuits in a hydronic system can operate independently without undue interference from each other.

Question 17

The purpose of differential pressure bypass valves (DPBV) is to ____ the differential pressure imposed on the distribution system by a fixed-speed circulator as the system flow rate decreases due to closing zone valves.

Accepted Answer

Differential pressure bypass valves (DPBV) are designed to limit the differential pressure in a heating or cooling system as the flow rate changes, ensuring consistent performance and protecting the system.

Question 18

Ideally, each circulator in a system will establish a differential pressure and flow rates that is unaffected by the presence of another operating circulator within the system.This very desirable condition is called ____.

Accepted Answer

Hydraulic separation is the very desirable condition where each circulator in a system establishes a differential pressure and flow rates that is unaffected by the presence of another operating circulator within the system. This is achieved by using hydraulic separation components, such as hydraulic separators, to physically separate the circulators from each other and ensure that they operate independently. The other answer choices (A, C, and D) are not correct as they do not describe this specific condition.

Question 19

A zone is any area of a building for which indoor air temperature is controlled by a single thermostat (or other type of temperature controller).

Accepted Answer

This is the definition of a zone as per industry standards such as the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).

Question 20

The time required to cool down or warm up a zone is significantly affected by the ____ of the heat emitter(s), and the building itself.

Accepted Answer

Thermal mass refers to the ability of a material to absorb and store heat energy. A building with high thermal mass can absorb heat during the day and release it at night, affecting how quickly a zone can cool down or warm up.

Quiz 11: Distribution Piping Systems