Hydronic Self Test Questions Flashcards
What are the 5 types of heat loss?
1) Radiation
2) Evaporation
3) Convection
4) Conduction
5) Respiration (so min doesn’t count)
What is the approx.. % of heat that a human body loses by radiation?
48%
What is the phenomenon known as, where a person can feel cold b/c they are sitting too close to a window or exterior door, when the temperature setting in the room is normal?
Cold 70
What is the name given to the set of interior room temperature conditions where the human body feels the most comfort?
The ideal heat curve
What is the temp that is read on a thermometer indicating?
The intensity of a heat present
What is the formula when calculating the BTUs involved in heating of water within a heating plant (ex: boiler)
BTUs = Mass x temp diff x S.H
What is the temp differential used in the design of most hot water heating systems that are fed from a boiler?
20 F
What is the min return water temp that should be maintained when using a non-condensing boiler?
140 F
What is the term known as, where heat is able to be applied to only the areas of a building where it is needed, rather than to the whole building?
Zoning
What would the K value for a material that has an insulating value of R = 22?
0.045 (1 divided by 22)
When designing a heating system, what is the January 2.5% value for the geographical area known as?
The Outdoor Design Temp
What is the allowable IDT that can be used residentially when performing a heat loss estimate if hydronic radiant panels are intended as the primary source of heat?
68 F
What is the allowable IDT for an unfinished basement?
18 C –> 64 F
In heat loss language, what is the term for heat that is lost from a building through conduction?
Transmission
What is the term for heat that is lost when cold air makes its way into the building through cracks / imperfections in the buildings envelope?
Infiltration
What would give a double - glazed window the best insulation rating?
Low “E” - Argon filled
What is the term given to the situation where, a heated slab-on-grade butts up to the exterior foundation wall, allowing heat to transfer between the two materials more easily than through the surround structure?
Thermal bridging
What would be the expected outcome of the rate of heat transfer if the temp diff. between two sides of a wall or ceiling were doubled?
The rate would double
What would be the expected outcome of the rate of heat transfer if the “R” value of a material were doubled?
The rate would be halved
How many air changes / hour (ACH) would a room with openings on 3 sides undergo?
1
What is the “R” value of 3” of extruded polystyrene?
15.0 (3 x 5.0 / inch)
Which variety of PeX tubing is manufactured by the Engel method / has a memory?
PeX A
Which variety of PeX tubing requires an oxygen - diffusion barrier when used in radiant floor panels?
PeX A, B, C
What min thickness of rigid polystyrene foam should be placed under a basement concrete slab that is heated by radiant mean?
2 1/2”
If a repair connection must be installed in a loop in a concrete over wood subfloor panel, where should the joint be located?
In the ceiling below
What is the purpose of the wide, extra bottom plate in above grade walls of a radiant floor panel system?
1) to allow for carpet nailing strips
2) Act as screed for the second concrete lift
3) to make up 1 1/2” of ceiling height that the concrete takes from the room
What takes the place of a boiler in a snow melt system / effectively separates it from the building’s heating system to prevent the entire system from having to be freeze protected?
A heat exchanger
What are radiant floor systems known as that heat the joist space below a floor?
Dry systems
What is installed along with batt insulation between joists that causes heat to be driven upward instead of downward?
Reflective foil
Does radiant ceiling panels operate at low temps?
No, at high temps
How would you lay radiant tubing loops in rooms that have 1 or 2 outside walls?
first pass = 6” from outside wall
turn 180
another 6” pass
resume normal loop layout
What is the max floor output from a radiant panel, in areas where people spend much time, over which supplemental heat will be necessary?
40 BTUH / ft2
What is generally the longest suggested loop length for 1/2” radiant tubing at a 20 degree pressure diff.
300 feet
What is normally used to locate tubing operating and embedded in a residential concrete floor?
an infra-red thermometer
Which multiplier would be used when determining the total tube required for a room with tubing laid at 6” O.C spacing
2:1
To what pressure / for how long should tubing be tested before being poured into a concrete mass?
100 psi / 30 min
What is the main characteristic of a boiler is used when choosing it?
its output
When assigning a head loss to a circulator, what is used as the head loss for the piping?
The single circuit w/ the highest head loss served by the pump
What are the 2 variables that are used in choosing a circulator?
Flow rate and feet of head
How many millinches are there in one foot?
12,000
What variety of valve is a circuit setter?
Globe
What is the name given to the strategy that uses a motorized mixing valve to automatically adjust its temp setting in reaction to changing outdoor or system thermal conditions?
Reset control
What is the term given to the practice of ensuring that the operation of one pump doesn’t affect the operation of another, if they share common piping?
Hydraulic separation
What characteristic of a brazed plate heat exchanger accounts for its high rate of heat transfer?
It’s inner plate surface area
What type of valve can be installed between the supply / return mains that will open when the pressure in the supply main gets too high, as might happen when only one or two zone valves are open and there is only one system pump?
A differential bypass valve
If 2 pumps are installed in parallel with each other, the approximate what will double?
Flow rate
What is the moving part of a switch known as?
The pole
What is the stationary part of a switch known as?
Throw
How are switches designated?
By their number of poles / throws
What type of switch only makes while a person is pushing or twisting it?
A momentary switch
What most accurately describes a heating thermostat?
Open on the rise
What are switches called that react to water temp?
Aquastat
What is this a picture of?
A pressure switch
What is the name of the switch that is used in a zone valve to prove that the valve is open?
An end switch
What voltage is applied to the two yellow wires of most zone valves?
24V AC
What voltage value is applied to the two red wires of most zone valves?
24V AC
In which leg of a circuit should switches be located?
Hot leg
What type of relay is most often found in use in hydronic heating systems
EMR
What is the voltage value of the coil in most relays used in hydronic heating control circuits?
24V AC
What voltage value do most pumps in hydronic systems use?
120V AC
What is this picture?
A low water cutoff
In the bottom right corner, what is it?
A pressure switch
Which type of relay has no moving parts but usually only controls one device?
an SSR
What is used to “scrub” latent heat from a condensing boiler?
A secondary heat exchanger
What is the principle behind the use of multiple pumps for proper flow rates in a primary/secondary piping system?
Hydraulic separation
Tees in a primary / secondary system should be placed no father than a max of — diameters apart
4
One USGPM will deliver — BTUH if the temp differential is 20F
10,000
What device, contained within a 4-wire zone valve, ensures that the pump won’t start / the burner won’t fire unless the zone vale is open?
An end switch
What term is sometimes given to a low-mass boiler?
Cold start
What is the main feature of a ladder diagram that makes it easy to follow?
The lines that represent wires won’t cross each other
Where are the low voltage terminals located on a relay / transformer centre?
On the face of the transformer
What terminal on a relay/ transformer center is the 24V AC neutral?
C terminal
Which terminal on a relay/terminal center powers all the thermostats and end switches?
R terminal
Which terminal(s) on a relay / transformer center would be wired to an AC system?
W and Y terminals
Where in the piping would a 3- way mixing valve be located?
At the mixing point
Where in the piping would a 3 way diverting valve be located?
In the boiler return piping
What is the main advantage for using a 3-way diverting valve rather than a 3-way mixing valve?
A diverting valve has less head loss than a mixing valve
What is one main disadvantage of using a 3-eay diverting valve rather than a 3-way mixing valve?
It needs a remote sensor
How many inlets / outlets does a 3 - way diverting valve have?
1 inlet / 2 outlets
What is the best option for tempering water to a low temp system due to its very low head loss?
a 4 way mixing valve
What is the term given to a controller that automatically adjusts system water temp when the temp outside rises or falls?
Outdoor reset
What is the setting known as where, on an outdoor reset control, the indoor and outdoor temp are equal, causing the system to shut itself off?
Warm Weather shutdown point (WWSD)
What is the next event that occurs after a zone thermostat closes?
The zone valve opens
What happens when 24 V AC is sent to “G” terminal on a primary relay / transformer center that is controlling a non- condensing boiler using a single pump? (G = Go for pumps/ burners)
The pump turns on and burner fires
What is the normal temperature setting for an indirectly -fired domestic water heater?
140F
How many contacts are needed on a secondary relay / transformer center to make the primary and secondary pumps start in a 2 temperature system?
two N.O contacts
Looking at a ladder diagram, if you follow a path from the C terminal of a transformer backwards through the diagram, what will you find?
Loads
In what arrangement and into which circuit are all the limit switches wired for a hydronic system that uses a gas boiler?
In series, in the burner circuit
A Radiant floor panel must have a N.C high limit on the piping feeding it that must shut off the burner if the temp reaches —F above its designed temp?
20
If needed where would a BVSS be located on a boiler? (Block Vent Safety Switch)
Near the draft hood
If a secondary transformer is necessary because of too much load, what will provide power for it?
Only the extra thermostats / zone valve motors
What component of a hydronic heating system is wired to the priority terminals of a zone control board?
The DHW zone valve
When the priority zone calls for heat, which other zones will still operate?
None
A voltmeter will be connected —- with the circuit or component being tested
In parallel
an ammeter that isn’t a clamp on style will be connected —- with the circuit or component being tested
In series
When checking amps on a 4 - wire cable, using a clamp on style ammeter, how many wires can be encircled by the meter’s jaws?
1
What is the single most important point when using an ohmmeter?
Make sure the circuit isn’t powered
What would be the next step involved after touching the leads together when “zoning” an ohmmeter?
Turn the adjusting screw so that the pointer is directly over the 0
What is field wiring?
Wiring that is not factory installed
What is the difference between “wire” and “cable”
Cable consists of individual wires
What is the purpose of a split plastic bushing when used with armoured cable?
to prevent abrasion of the wire insulation
What does CEC stand for?
Canadian Electrical Code
What type of box must be used with metal conduit?
Metal
If a device box can be dismantled / made larger, it is said to be?
Gang -able
How are box entry fittings attached to boxes?
Through knockouts on the box wall
Exposed conductors must be protected from damage if within — of the floor
1.5m
What is the difference between BX and Teck cable?
Teck is waterproof
BX is not
What is used to connect PVC conduit to a box?
a threaded adaptor
What type of material is rigid metal conduit?
Galvanized schedule 40 pipe
What is any rigid enclosed or semi-enclosed channel that protects, routes and hides cables / wires known as?
raceway
What is the power output limitation for a class 2 circuit?
100 Watts
What is the general rule regarding separation distance between low voltage / line voltage conductors that are in close proximity to each other?
Maintain at least 2 inches physical distance between them
A “marrette” is an example of a — of wire connector
Solderless
How much length of tightly - twisted bare wire ends should there be under a wire nut connection?
5/8” – 3/4”
What device is suggested for use when connecting small diameter wires, to prevent them from breaking if twisted together?
A terminal strip
How much wire must be stripped for a crimped connection?
1/4” – 3/8”
What must not be joined using a soldered connection?
Two bonding wires
What is suggested to be used whenever making a soldered wire connection, to avoid melting the wire insulation?
A heat sink
