Deck 11: Distribution Piping Systems

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.

Answer 1

True

Question 2

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

Answer 2

False

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.

A) one specific
B) two or more
C) at least three
D) possibly none

Answer 3

B

Question 4

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

A) counterproductive
B) instrumental
C) essential
D) irrelevant

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.

A) circulatory
B) serpentine
C) head loss
D) common

Question 6

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

A) hydroplastic
B) home run
C) hybrid
D) green

Question 7

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

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.

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.

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.

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.

A) spatial
B) hydraulic
C) zoning
D) R-value

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.

A) trial and error
B) selective pairing
C) elimination
D) iteration

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.

A) hydraulic separation
B) hydraulic equilibrium
C) thermal envelope
D) distribution efficiency

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.

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.

Question 16

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

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.

A) accelerate
B) equalize
C) limit
D) increase

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 ____.

A) hydraulic equilibrium
B) hydraulic separation
C) the pump curve
D) ideal circulation

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).

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.

A) thermal envelope
B) thermal mass
C) ambient temperature
D) setpoint temperature