Hydronics Flashcards
what is the definition of human comfort relative to temperature
When you feel neither warm nor cool
Which type of hydronic system would use gravity flow
High temperature heating
Describe hydronic system
Heating and cooling system that uses water or or HTF as a heat transfer medium
brine or a water glycol mixture is commonly referred to as
HTF
How Many BTU’s are required to heat one pound of water from 32 to 212
180 BTU 212-32
In order to provide accurate indoor temperatures the heat supply to the building must be equal to
The heat loss of the building
What are the four types of heat transfer
Conduction, convection, radiation, evaporation
Calculate the gpm for an 80 MBH heat load using water as the HTF with a delta T of 20 degrees
8 gpm BTUH=500x specific heat x Delta T
How is TEL (Total equivalent length) meassured and calculated
Measure longest circuit and add 50% for fittings and terminal units
which type of heat, when added or removed from a substance creates a change of state?
Latent heat
Define humidity
The amount of moisture in the air
What is the dry bulb temperature
Temperature of air taken with a standard thermometer
which tool is used to determine relative humidity
Sling phychrometer
How is the rate of flow measured
gallons per minute
select three types of heat transfer
Radiation convection conduction
Any pressure above a perfect vacuum is measured as
Psia
What is atmospheric pressure at sea level
14.7 psia
Temperature comfort is accomplished by controlling
Temperature and humidity
Room humidity is measured with a
Hygrometer
Describe enthalpy
Total amount of energy of a substance
Select the best statement regarding thermal conduction through and object or substance
Transfer of heat happens when both materials are in contact
What is another term for pump capacity
head pressure
Evaporation occurs when water absorbs _____ heat
Latent
by controlling the rate of _____, hydronic heating and cooling systems allow the body to be comfortable
Heat loss
What is absolute pressure
Gauge plus atmospheric pressure
what is the formula for calculating pump gpm
heat loss divided by 10,000
What is the general equation for calculating sensible heat change of fluids
Btu= gpm x s x delta t x 500
How is vacuum measured
In Hg
What is the maximum design pressure for a low temperature boiler
160psig steam is 15psig
Select the correct valve that would be used to regulate the rate of HTF flow in a pipping system
balancing valve
Name four main components of a chiller system
compressor condenser, evaporator, refrigerant
Select the devices which would be included in a make up water system
pressure reducing valve, backflow, isolation
select the best description of a LWCO
low water cut off
which boiler has the highest output rating
electric
what device is used to protect a potable water system from cross contamination
backflow preventer
a condenser acts as a type of
heat exchanger
low pressure boilers are classified by
type of construction
Low pressure boilers have specific pressure and temperature limits, what is the maximum pressure temperature limit for these boilers
15psig for steam, 160psig for water @ 250 degrees
Which type of device is attached to the boiler to assist in the management of air in the hydronic system
boiler fitting
Which type of boiler uses a microprocessor controlled combustion which automatically adjust air fuel mixture
condensing
which device protects the boiler from pressures above maximum design pressure
Relief valve
fuel oil burner _____ fuel oil to increase contact with combustion air for maximum effciency
atomize
What does ASME boiler pressure Vessel Code require if the output of a boiler is 400,000 BTUH or
LWCO
An output rating is the total amount of heat a boiler will produce in
one hour
What is the device that can be used to both heat and cool and area
heat pump
When a heat pump is in cooling mode the outdoor device is
The condenser
As a vapor is compressed in a compression refrigeration system what happens to the refrigerant
Temperature increases
In a compression refrigeration system, where is the heat absorbed
Evaporator
The hydronic cooling cycle is composed of _____ seperate and distinct cycles that create the complete system
5
what type of flow has better heat transfer in a coil
Counterflow
a ROT can be used to calculate fill pressure of a hydronic system, when using the ROT what is considered a standard height per floor
10
What are the three functions of a triple duty valve
Flow control, check valve, isolation
Which impeller is most efficient for pumping clear liquids
vane and paddle
how many pipe diameters of straight pipe do you need between the wye strainer and the pump
5
which consideration is most important when starting a pump for the first time
check alignment of pump and motor
pumps, when subjected to lift task must be _____ before starting the motor
primed
Which term describes an impeller that has vanes attached to a hub that is not enclosed or supported by a shroud on either side
Open impeller
which term describes a hydronic system that is sealed to prevent the entrance of air from the atmosphere
closed system
why is glycol not used at 100 percent concentration
very high viscosity
which pump is used most often for a closed hydronic piping system
centrifugal
In a primary secondary pumping arrangement where is the largest circulator installed
Primary loop
A hydronic system uses _____ to transfer heat
HTF
Where would you install a triple duty valve
Discharge side of the circulator
What is the maximum spacing recommended for the closely spaced tees on a primary secondary system
4 pipe diameters
What are the two types of pump misalignment that must be checked
Angular and parallel
What is the violent action of a vapor bubbles in a centrifugal pump
Cavitation
When calculating pump capacity in an open system you must
Add static head to piping resistance
A pump is not moving any flued, what should you check
pump is primed
What is the maximum theoretical lift of a pump
34 feet
The best place for air separation is the at the boiler, why
HTF is at a high temperature and low velocity
A typical pressure at the top of a hydronic system with the pumps off would be
4psig
A system is seven stories tall and it includes a captive diaphragm expansion tank in the basement what is the adjusted tank pressure? (10 feet per floor)
36 psig
Select three ways air can exist withing a hydronic system
Air pockets, entrained air bubbles, dissolved gases
A closed hydronic system has a static head of 30 feet. What is the cold fille pressure at the pump
17psig
Which of the following flow rates is best for air removal
2 fps
Which location is preferred when connectiing a pre charged expansion tank
Suction side of the pump
A properly installed closed loop hydronic system that has been filled and properly maintained ______ needs additional HTF
Rarely
What is the total pitch for a pipe connecting a compression expansion tank that is 5 feet long
1”
Which one of these devices is an example of a final control
Zone valve
Which check valve relies on a hinged disk within the valve body
swing check
what is used to relieve trapped air ina hydronic system
Air Vent
Which fitting or device is used in a one pipe system to induce HTF flow into another pipe
Diversion fitting
combination balancing and purge valves have four basic functions which of these choices is not a function of this device
Temperature
what is another name for a Venturi tee
Diversion tee
what is an ASTM standard for steel pipe
ASTM A53
Descibe a full way valve used to regulate flow in which a threaded stem raises and lowers a wedge shaped disc
gate valve
Which valve allows fluid flow in one direction
check valve
Copper is often used in hydronic and refrigeration systems, list the three types of copper tubing in order of wall thickness
K,L,M
A U shaped section of piping that absorbs thermal movement is a
Expansion Loop
What is the maximum horizontal hanger spacing for 3 inch polypropylene pipe
4 feet
_____ prevent piping in horizontal runs from sagging and leaking
hangers
Select the best application for a globe valve in a hydronic piping system
Throttling or flow control
Example 20’ high water column time .433 is how many psig
8.66 or 9psig
8.66psig times 2.31 is how any feet of head
20 feet of head
How many BTUs are required to change one pound of water at 212 degrees to steam
970
when connecting the makeup water fill line, what is the best location for installation
point of no pressure change
A building is 19 floors, each floor is 12 feet, pumps on first floor, what is the psi you should charge the system to in order to correctly charge with 4 psi at the top floor
228’ x .433= 98.7psi + 4= 102.7
which piping system is identified by first supplied last to connect to the return
Direct return
what is a zone
a circuit that is controlled by one thermostat
When using an eccentric reducer in a hydronic system, how is the fitting installed
flat on top to keep the air moving
Which rule applies to the branch takeoffs when piping terminal units on a one pipe system
should be the same width of the terminal unit
To prevent debris from collecting in the heat transfer units how is the branch piping installed
top or 45 off of main
Which system has separate heating and cooling functions with dedicated supply and return piping
four pipe
which piping designs are two pipe systems
direct return and reverse return
which type of fiting is used to reduce the pipe size in a hydronic horizontal main
Eccentric
what are the two types of one pipe system
single main, series loop
