Hydronics 12

For typical residential or light commercial applications, a temperature difference of about ___ may be used for both heating and cooling applications.

10°F to 20°F

When terminal units are used in commercial and industrial buildings, the temperature of HTF leaving a boiler typically is ___.

160°F to 200°F

When HTF temperature rises, a decrease in pressure drop in hydronic systems could be as much as ___%, which could result in oversizing of the piping and circulating pumps.

30

Relationships shown on pipe sizing charts are based on the normal HTF temperature of ____________________°F for specific piping roughness.

60

The water flow velocity should normally be between 2.5 fps and ___ fps.

8

In two-pipe reverse-return systems, the supply pipe gets progressively larger as it goes out from the boiler or chiller.

False

On drawings, piping can run through beams, columns, stairwells, elevator shafts, or areas where plumbing or electrical devices may be located.

False

Total head is the effect of friction in a pipe.

False

When HTF temperature rises, the flow resistance of HTF rises, and the pressure drop in pipe segments decreases.

False

When a piping system includes multiple segments, the pressure drop for the initial segment is found last.

False

When a piping system is sized for heating and cooling, the smaller required flow rate is used for sizing the components of the system.

False

___ head is a function of the weight of HTF and the vertical height of the HTF in the system above a pump.

Static

In one-pipe series systems, the pipe size remains the same throughout the system because the flow rate remains the same.

True

In some piping systems, the temperature differences vary through each piping section and terminal unit.

True

On the piping layout, each terminal unit is connected to the supply pipe and the return pipe.

True

The equivalent length of pipe is based on the pipe size and velocity of the HTF.

True

The rate of water flow through a pipe or an orifice is a function of the pressure exerted on the water and the size and material of the pipe.

True

The type of terminal unit used in a hydronic heating or cooling system depends on the degree of temperature control required in the building.

True

The equivalent length of an entire piping system can be found by converting all fittings to ____________________ equivalents.

elbow

The required size of a pump for each piping circuit or system is found by using the total ____________________ and the total head of the pump.

flow rate

System pressure drop is the decrease in HTF pressure caused by ____________________ between the HTF and the inside surface of piping as HTF flows through the piping.

friction

When one pump is used with multiple piping circuits, the piping circuit with the ___ is used to size the pump.

greatest total pressure drop

When designing piping systems, temperature difference represents the ___ in the system.

heat loss

The pressure drop ___ as the flow rate increases and the piping size decreases.

increases

____________________ drawings are drawings of the floor plan of a building that show walls, partitions, windows, doors, fixtures, and other details that affect the placement of piping and terminal devices.

layout

____________________ system temperatures improve system safety and operational costs but can require larger terminal units for proper heat exchange.

lower

Small piping systems typically have ___ pump(s) for the whole system.

one

In one-pipe primary-secondary systems, the terminal units are located on secondary circuits that are in ____________________ with the main or primary circuit.

parallel

A parallel pumping installation commonly used is system ____________________, in which two pumps are used sharing common suction piping.

redundancy

The ____________________ of the inside surface of piping, which affects friction loss, varies depending on the piping material.

roughness

In addition to alternate pumping, the pumps in ____________________ can provide for both pumps to be operational at the same time.

series

The total pressure drop in a piping system is the ___ of all system pressure drops in the supply side and return side of a piping loop or system.

sum

____________________ for open hydronic systems is the sum of friction head and static head.

total head

In ___ systems, the supply pipe and return pipe are typically the same size in each pipe section between terminal devices.

two-pipe direct-return

Water flow ___ is the speed at which water moves through a piping section.

velocity

____________________ is the volumetric flow rate of water as it moves through a given pipe section.

water flow rate