Hydronics Flashcards
A normal adult generates in light activity generates how much heat?
400 BTUs per hour
A ton of cooling
The amount of cooling provided by melting 1 ton of ice within a 24-hr period
Heat capacity
The amount of energy needed to change the temperature of a material by a certain amount
Specific heat
The ratio of the heat capacity of a substance to the heat capacity of a standard substance at the same temperature.
Liquids - water
Gases - air
A given volume of water can absorb over ______ Times more heat as the same volume of air for the same temperature change.
3400
The overall hydronic system this consists of four interrelated subsystems:
- Heat Source
- Distribution System
- Heat Emitters
- Control System
Heat transfer equation
Q = (A/R)(🔺T)
Typically wood-framed walls will have from ____ to _____ of the walk areas solid framing across the insulation cavity. The lower range would be for ____ on-center framing and the higher for _____ on-center framing.
10-15%
24” with insulated headers over windows and doors
16” with solid headers
Supporting Copper Tubing Spacing
1/2” - 3/4”: 5 feet
1 - 1-1/4”: 6 feet
1-1/2” - 2” : 8 feet
Vertical: 10 feet
Equation for head produced by a pump
H = (144 *Pd)/D
Pd = pressure differential between inlet and outlet of pump D = density of fluid
Digital Input
an input which can only have one of two states; open or closed
Target vs. controlled variable
Target - Is the desired ideal status of the controlled variable
Controlled - usually actual reading of air temp, etc.
Error
Deviation between target and contolled variable
Three common types of processing algorithms:
(P) Proportional
(PI) Proportional-integral
(PID) Proportional-integral-derivative
Proportional Processing
the magnitude of the output signal depends only on the error between the target and measure values of the controlled variable - operates within a band range which ranges from zero to fill output.
Proportional-Integral Processing
determines the output signal based on both the amount of the error, as well as how long the error has existed (only practical in electronic controls)
Proportional-Integral-Derivtative Processing
adds the ability to monitor the rate of change of error to the response provided by a PI controller. Allows the controller to predict what the errror is likely to be in a short time into the future and adjust the present output accordingly.
Number of Poles
is the number of independent and simultaneous electrical paths through the switch
Number of Throws
is the number of position settings where a current can pass through the switch
Relays
Electrically operated switches
Delay-on-make Mode
Prevents the contacts from moving until a user-specified time delay period has elapsed from when the input signal is turned on.
Delay-on-break Mode
The contacts are held in their energized position until a user-specified time has elapsed.
Contacts wired in a certain configuration represent an “AND” or “OR” decision. What is the wire configuration?
AND - Series
OR - Parallel
