HYDRONICS CHAPTER 7

Generally, for a two-pipe system, the connections to risers, branches, or terminal units are taken off the top of the main at either a 45 degree or ____ angle from the horizontal plane.

90 DEGREE

What is a circuit setter?

A circuit setter is a combination balancing and purge valve.

Brief description of direct return system

A direct return piping system is a type of 2 pipe system

Brief description of diversion fitting

A diversion fitting is a fitting that creates a greater-than-normal pressure drop in a line in order to divert flow to another line. basically creates an area of low pressure to which the higher pressure line natural flows.

Brief description of a series loop system.

A series loop system is a type of one pipe system where the primary circuit provides HTF to terminal units via direct connection. No secondary circuit, terminal units serve as part of the main.

Brief description of a single main system

A single main system is a type of one pipe system where a primary circuit provides HTF to terminal units that are connected via a separate secondary loop.

Expansion and contraction protection is not needed on piping since cooper is annealed. (T/F)

FALSE (Annealed means nothing copper will still expand and contract)

Flow in the main of a series loop system will not be affected by reducing or stopping flow in individual terminal units. (T/F)

FALSE (Flow in the main will be affected as terminal units serve as part of the main)

In a one-pipe system, the supply connection to the terminal unit must be downstream from the return connection (T/F)

FALSE (In a one pipe system the supply connection to the terminal must be *UPSTREAM*)

Bull-head connections should be used on the return piping of divided circuits to the heat source.

FALSE (Should not, if one of the circuits is longer than the other of the same pipe size, an unequal flow pattern will occur)

The temperature of a secondary loop HTF is not sufficient to provide the proper heat transfer needed for the terminal unit supplied by the tertiary loop (T/F)

FALSE (Temperature of the secondary loop is sufficient)

A ____-pipe system is used where each terminal unit or zone may heat of cool independently of all other units or zones and is the most efficient

FOUR

Main line or main

Large diameter pipe that distributes HTF from the heat source or chiller to smaller branch pipes.

The monoflo or diversion tee should only be used in this system

ONE PIPE SYSTEM

When piping must be run around an obstacle, such as a beam, it is recommended to.

PIPE UNDER THE BEAM

A diversion fitting is a fitting that creates a greater-than-normal ____ in a line in order to divert flow to another line

PRESSURE DROP

The ____ circuit or loop is the piping directly connected to the heat source or chiller inlet and outlet and to which the compression or pre-charged expansion tank is connected

PRIMARY

Circuit

Portion of main carrying only a part of the total capacity of the system.

A ____ system is a piping system that circulates HTF through a single main in which each terminal unit serves as a portion of the main

SERIES LOOP

The main in a one pipe system.

STAYS THE SAME SIZE THROUGHOUT THE ENTIRE LOOP.

Trunk of trunk line

Section of the main in a multiple circuit system that carries the combined capacity of the circuits

A secondary circuit or loop is a separate piping configuration connected to the primary loop and supplies HTF to separate heat transfer loads or terminal units. (T/F)

TRUE

General piping layout should be as simple as possible. (T/F)

TRUE

If proper air control equipment is installed at the heat source further venting should not be necessary (T/F

TRUE

In a direct return system, starting at the boiler, the first terminal unit taken off the supply main is the first to connect to the return main (T/F)

TRUE

In a reverse-return system, the first terminal unit taken off the supply main is the first to connect to the return main. (T/F)

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 a two-pipe system, the size of the main is reduced as branches are taken off the main (T/F)

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 (T/F)

TRUE

Risers are vertical mains or large vertical branches from which smaller branch lines are taken off to provide HTF to terminal units.

TRUE

The two types of one-pipe systems are the series loop system and the single main system. (T/F)

TRUE

There are two main styles of diversion fittings in use: the Monoflo fitting developed by Xylem, Inc. and the Venturi fitting developed by Taco (T/F)

TRUE

Zoning allows for the independent control of separate building spaces, which will, in turn, help to reduce energy costs by using only the energy required to heat or cool a zone when and where it is needed. (T/F)

TRUE

Where unit heaters comprise either all of 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 pip system. (T/F)

TRUE (This is because the high pressure drop through these types of units and the large HTF flow required may exceed the diversion capacities of diversion fittings.)

The ____ line is the section of the main in a multiple circuit system that carries the combined capacity of the circuits

TRUNK

A ____ hydronic system is used where the terminal units, such as unit heaters and convection units for heating and cooling, have very high pressure drops

TWO-PIPE

in most cases only one diversion fitting is required to connect a terminal unit. What is the exception.

The exception occurs when the diversion fitting is being used on a riser. In this case one diversion fitting will have to be used on the return and one on the supply as gravity makes flow more difficult. Additionally going the other one hot HTF wants to rise and cool HTF wants to fall.

A ____ is a section of a building that is controlled by one HVAC controlling device

ZONE

Where should balancing valves be installed?

balancing valves should be installed in the return line