Heating / Cooling Systems (B - books) Flashcards
(218 cards)
1
Q
One BTU is described as what?
A
The amount of energy it takes to raise 1 lb of water 1 degree Fahrenheit
2
Q
What is the metric unit of energy
A
Joule (J)
Kilojoules (kJ)
3
Q
1 BTU = how many kJ?
A
1.054
4
Q
What is the metric equivalent of BTU?
A
Kilowatt (kW)
5
Q
1 kilowatt = how many BTU/h?
A
3412 BTU/h
6
Q
What are the 3 main processes of heat transfer?
A
1) Conduction
2) Convection
3) Thermal radiation
7
Q
Heat transfer units (emitters) use the process of what to transfer heat to rooms or zones?
A
Conduction, convection and radiation
8
Q
How does heat transfer between 2 materials (that are touching) with different temperatures?
A
Through conduction: Heat from warm material is conductive to cool material
9
Q
What else is Convection called?
A
Gravity circulation
10
Q
How does Radiation heat transfer occur?
A
Through electromagnetic heat rays emitted directly from a heat source –> receiving material
11
Q
The amount of heat transfer by a radiator depends on what?
A
It’s surface area / temperature
12
Q
What is the best type of radiators of heat?
A
Rough and black –> cast iron stoves
Light-coloured, smooth / shiny materials –> reflect heat
13
Q
As the temp of radiating material increases, what happens to the amount of radiation?
A
Increases
14
Q
In domestic / small commercial buildings, what is the max PRESSURE of steam?
A
Less than 15psig (200 kPa)
15
Q
House Steam systems should not operate at pressures higher than what?
A
2 psi
16
Q
What is a Hartford Loop?
A
A piping arrangement designed to prevent complete drainage of boiler should a leak develop in wet return.
17
Q
What is the pitch in a counterflow system?
A
Pitch must be at least 1” in 10 feet
18
Q
What is an advantage of forced-air system?
A
The movement of the return air via a filter that removes dust / airborne particles
19
Q
What is the downside of forced air heating?
A
The difficulty in maintaining a comfort level in all areas of the house.
20
Q
All furnaces consist of what?
A
- air filter
- blower
- heat exchanger/element/coil
- ductwork
- various operating / limit controls
21
Q
All new installations of residential furnaces must have a min efficiency of what?
(As per the Canadian federal efficiency guidelines)
A
90%
22
Q
Mid-efficiency furnaces have a category of what and use what type of venting material?
A
Category 1
Type B venting material
23
Q
What category are High-efficiency furnaces and what type of venting material is used?
A
Category 4
Plastic Type BH Venting material
24
Q
In-shot orientation allows mid/High-efficiency furnaces to be installed which way?
A
Upflow - common for multi-level homes
Downflow- rancher style w/ crawl space
Horizontal flow - mounting in a crawl space or attic
Known as convertible or multi position furnaces
25
All forced air furnaces require what?
Air filtration to operate safely / efficiently
26
How does a Heat pump extract heat from the environment?
By either the ground or outside air as the source through refrigeration
27
What does a Heat coil combine with?
Hydronic (hot water) heat source w/ forced air delivery
28
What is a Plenum?
It is the duct that connects directly to the furnace
29
True or False: There is a supply plenum and a return plenum.
True
30
What 2 places can an air filter be mounted
1) Inside the blower compartment
2) Onto the return air plenum (where it attaches to the furnace)
31
What are the different thermostate options?
- heat only
- heat / cool
- analouge
- digital
- digital/ programmable
- wi-fi enabled aka smart
32
Why are programmable thermostates the popular choice?
Due to air's low thermal mass
33
What removes the heat in a Hydronic cooling system?
Cooling tower and Chiller
34
Why is Water ideal for heating and cooling?
It is non-toxic, non-flammable / readily available.
has a high heat storage capability
35
What princible did the early hydronic heating system use?
## Footnote
Eary hydronic heating system also called Gravity System
principle of buoyancy
36
How are convection currents created in boilers?
- water becomes less dense when heated
- The density differential (bn supply / return) creates a convection current
- Hot water gets carried up and through pipes --> Heat transfer unit (HTU)
37
How did electricity help with moving water?
Electricity created pump (eye roll) with helped move water bn heat source / emitters.
Resulted in better control / smaller diameter piping
38
What % of a person's body heat is released by thermal radiation --> colder surface?
48%
39
What uses less energy: Hot water heating system or forced air heating system?
Hot water heating systems
40
What 2 categories do boilers fall under?
Low temp boilers
High temp boilers
41
What is the max temp and pressure of a low temp boiler?
Max temp = 120C / 250F
Max pressure = 1100kPa (160 psig)
Exception: cast iron boilers = max pressure: 207 kPa (30psig)
42
What is the max pressure / temp of a High temp boilers?
Everything that exceeds the low temp boilers max rates
43
What are the 2 types of boilers?
1) hot water
2) steam
44
What other classifications do boilers have?
(theres's 5)
Heating method - fire tube / water tube
Material used in construction
High mass or low mass
non-condensing or condensing
high pressure and low pressure
45
True or False: Steam boilers need a pump.
False
but pumps are installed to return condensate back to boiler
46
What is the operating pressure of a low-pressure steam boiler?
105 kPa (15 psig) or less
47
In order to stay below water's atm boiling point what temp do Hot water boilers normally operate at?
82 C (180 F)
48
What does a pressure reducing valve do and where is it located?
- maintains set pressure
- installed on boiler's inlet water makeup
49
Steam creates what...
Pressure
50
What does ASME stand for?
American Society of Mechanical Engineers
51
Steam for heating does not exceed what pressure?
105 kPa (15 psig)
52
How are fire-tube boilers identified?
By the number of "passes" that the heated gas makes
Ex: Three pass boiler = flue gases pass via firebox once / water chamber twice
53
What are cast iron boilers classified as?
High mass boilers (dt large water vol)
Holds 40-64L (10 - 16 gal)
Weighs 130 - 180kg (300 - 400 lb)
54
What temp do boilers heat water to?
bn 77 - 88 C (170 - 190F)
55
What temp does water drop to before returning to boiler?
6.5 C (20 F)
56
a non-condensing boiler cannot have return water be at what temp?
It cannot be any lower than 60 C (140 F)
57
What is the returning temp of a condensing boiler?
below 60 C (140 F)
58
Modern condensing boilers are designed to function how?
with low return water temp that condenses w/in combustion chamber of the boiler
59
What is the condensate put through before being drained via sanitary drainage system?
Acid neutralizer
60
Packaged boilers can be made out of what?
Cast iron
copper tube
steel tube
stainless steel
61
Packaged boilers come with what?
- Insulated jackets
- min size circulator
- electrical controls (all ready to go)
62
A circulator is removed from a packaged boiler and installed where?
## Footnote
Page 18
On the supply piping downstream on the expansion tank.
63
What is the formula for efficiency?
(output / input) x 100
Remember: you cannot have more than 100% efficiency
64
What are chillers in Commercial Cooling Equipment?
(pg 25)
Chillers are the heart of commercial cooling systems
65
True or False: In cooling systems: the refrigerant mixes with the cooling medium (aka chilled water)
False: refrigerant / colling medium never mix
66
The chilling of water (in a refrigerant system) is done how?
Done by the evaporator, once now chilled refrigerant, is pulled into a compressor where the temp and pressure is increased.
(page 25)
67
Air-to-water heat pumps require controls that monitor what?
The dew point --> in order to avoid condensation forming on cool surfaces (can create dampness --> mould)
68
What is another term for water-to-water heat pump?
ground source heat pump or Geothermal
69
What is the difference bn geothermal and ground source heat pump?
True geothermal = taps into heat emitted from underground hot springs
Ground source heat pump = conducts latent heat from below earth surface
70
What is a water-to-air heat exchanger?
Hot boiler water gets piped into W2A heat exchanger --> water circulates via heat exchanger --> fan pushes air via finned coils
(Acts like a radiator in a car)
71
What is the CSA B214 Code ?
It is the installation code for hydronic heating systems in Canada
Section 5 = heating equipment
72
All heating equipment must be installed according to what?
Codes / regulations specified by the region in which they were installed.
73
True or False: Multiple codes will have to be used when installing heating equipment.
True: Boilers must meet the requirements of applicable boiler / pressure vessel regulations (as well as boiler, building, plumbing, electrical , gas / fire codes)
page 42 B-2
74
What does the Canadian Electrical code state in regards to a branch circuit?
That all heating equipment must have a dedicated branch
75
How high does a boiler heater water to?
To temps as high as 88 C (190 F)
76
What are the 4 groups of emitters?
1) gravity circulating convectors
2) forced circulating convectors
3) Radiators
4) Radiant panels (in-floor heating)
77
How are gravity circulators installed?
- surfaced mounted
- recessed into the wall
(insulation installed behind prevents heat loss through wall)
78
How are gravity circulation convectors installed?
- Surfaced mounted
- Recessed into the wall
(installing insulation behind the wall --> prevents heat loss)
79
How are residential circulating convectors installed?
Mounted at baseboard level beneath windows
80
Where are commercial grade convectors located?
Normally found in stairwells / common areas
81
What happens to the cold air that moves downward from the window towards a convector?
The cool air mixes with the warm air from the convector => both drafts produce a more even room temp.
82
What is a Convector?
Baseboard heater...
83
Commercial wall mounted convectors are the modern day what?
Are the modern day cast iron radiator
84
Gravity convectors rely on what to transfer temp?
temp differences / air densities to create convection
85
Forced flow systems combine what 2 things to move air?
heating element and a fan (or blower)
86
What are the different names for a fan coil?
Unit heaters, duct heaters and kickspace heaters
87
How does a fan coil work?
The fan (placed on the upstream side of coil) pushes air across the coil --> air picks up heat and is pushed out towards room.
88
Where are unit heaters and overhead fan coils mainly used?
In commercial buildings (where its advantageous to deliver heat from above)
89
What is another name for vertical unit heaters?
Projection unit heaters
90
How do vertical unit heaters work?
They push air downwards
Are mounted near the ceiling
91
Deflecting louvers (below fan) can do what?
can be adjusted to direct the air
Diffuser cone can be used to decrease drafts
92
What do Horizontal unit heaters do?
Move air at lower velocity than vertical unit heaters
93
How do horizontal units provide more comfort?
through their ability to direct airflow through adjustable discharge deflectors.
94
What is another name for a Kick-space heater?
Under-cabinet fan coils
95
Where are kick-space heaters normally located?
kitchen or bathroom in the "kickspace" below cabinets
96
What can Forced-flow wall mounted convector unit be referred as?
a wall mounted fan coil
97
What does the term radiator refer to?
Both freestanding cast-iron radiators / baseboard radiators
98
How does heat transfer happen for radiators?
Conduction --> hot water inside radiator warms outside
Radiation --> warm outer surface of radiator emits heat to objects in the room.
99
How does a free standing cast iron radiator emit heat?
60% via radiation
40% via convection
100
What are the general measurements of a freestanding radiators
They are constructed to be no wider than a window
(in order to maximize the use of convection currents w/in the room)
101
What do the end sections of baseboard radiators have?
tappings (female threaded connections) for connecting supply / return piping
102
Where are baseboard radiators located?
On outside walls (like baseboard convectors)
103
How do radiant baseboard transfer heat?
Hot water runs through a copper tube w/in the housing / heats the front panel (does not contain fins)
104
If a Panel radiator transfers heat via convection, how would that happen?
Fins would be included in its set-up --> it would capture heat --> create convection currents
105
What is a benefit of panel radiators?
it is relatively small amount of wall or ceiling space they require.
106
What is the main benefit of radiant floor panels?
An increased level of comfort
107
What is considered a comfortable room?
One in which the temperature in the room matches human body requirements
108
What is the temperature of boiler water used in radiant panel flooring systems?
Max 49 C (120 F)
--> Prevents floor/ occupants from getting too warm
109
What are the ups and downs for radiant systems? (in regards to economy)
Plus = are least expensive to operate
Not so plus = Initial install cost is bad
110
Hotter water means what?
Less area of transfer unit needed
Greater arear of transfer units = use of lower temp heat sources (heat pumps + condensing boilers)
111
What does design temperature difference mean?
It is the water temperature drop
112
Most systems are designs to release how much temp from water?
11 C (20 F)
113
If one room has a high heat transfer unit, what does that mean for the rest of the rooms?
Other rooms may receive less heat than needed
114
What is the primary function of air vents?
To rid the system of trapped air
115
Where must air vents be places?
at all the high points in a piping arrangement + be accessible for servicing
116
How much will baseboards expand when heated?
5 mm per 3m (3/16" / 10') when temperatures= 4 - 93 C (40 to 200F)
117
What must you do to allow for piping mvmt / coming through floors?
Drill larger holes (if you do not, pipes rub against floor / squeak loudly)
118
What is important to not for rods on unit heaters?
Rods should be double nutted at each connection to ensure that vibration won't loosen them
--> May also be seismically restrained
119
Counterflow piping direction is best for?
Most heat exchangers
120
Isolation valves should be installed where?
On both supply / return piping connections
121
Unit heaters are well suited for what locations?
Where there is a need for quick heat recovery (service station or buildings w/ frequently opened doors)
122
Vertical heaters should be spaced how far apart?
17m (50') for best performance
123
What is a circulating pump's job?
to pump liquid through piping system
heat source --> heat emitter --> return heat source
124
A centrifugal pump can be found where?
On a hot-water system
125
What does a centrifugal pump consist of?
Page 8 B-4
- electric motor spinning an impeller w/in a housing (aka Volute) containing liquid
126
What is the preferred location of a pump?
on the supply main immediately downstream of compression tank
127
what is the "point of no pressure change" concept?
When a system is drained, whatever the pressure is in the air side of expansion tank = the pressure at the point of no pressure change at the water side of the expansion tank...
128
Why is it important to mount larger pumps on vibration mount brackets?
Pumps vibrate when operating, mounting brackets help keep pumps in place
129
What is included in an isolation flange?
Flange and ball valve
130
Where should a strainer be installed?
Upstream of the pump in order to pick up any solids that are in the system
131
What 2 factors determine the selection of a centrifugal pump?
1) flow rate
2) head pressure
132
What does feet of head refer to?
Pressure
133
What is feet of head expressed in?
pounds per square inch
psi
134
What does 1 foot of head =?
1 foot of head = 0.433 psi
(1 psi = 2.31 feet of head)
135
What is flow measured in?
US gallons / min (USGPM)
136
What is dewpoint temp at atm pressure?
53 C (127 F)
137
What is a safe temperature drop that avoids the dewpoint (in non-condensing boilers)?
11C (20F)
138
Why don't you want water returning to a boiler lower than the dewpoint?
Causes condensation / corrosion of the boiler's heat exchanger surface
139
Return water temp to a non-condensing boiler should never be lower than what?
60 C (140 F)
140
What is the USGPM flow rate formula?
USGPM = delta T x 60 x 8.33
delta T = temp drop desired (usually 20 F)
60 = number of min in an hour
8.33 = mass in lbs of US gallons of water
141
1 USGPM = how many BTU/h?
10 000BTU/h
142
When manufactures publish charts, what does the curve represent?
the capacity of the pump (pg 20)
143
What are 6 problems of air being trapped in an hydronic heating system?
1) Noisy flow
2) Increased corrosion
3) poor or possibly no flow
4) poor heat transfer
5) Cavitation leading to circulator damage
--> dt above reasons air removal must be a priority in system design
144
Where is a central air separator located?
on the supply piping leaving the boiler
- DT air being most easily removed from water whenever it is hottest / slowest
145
What else are Manual air vents referred to as?
Coin vents or bleeders
146
Where is the most common location for a Manual air vent?
Downstream (return) end of heat transfer units
147
The slotted steam air vent is also referred to as what?
Coin vent
148
When do automatic air vents open and close?
Open = automatically when air is present
Close = automatically what water is present
149
Automatic air vents should be installed with which other vent?
Isolating valve --> so that repairs or replacement can occur
150
What else is an Air Purgers called?
Air separators or Air scoops
151
Where are air scoops installed?
Horizontally on the main as close to the boiler as possible
152
What can be installed at the bottom of an air scoop?
Diaphragm compression tank
153
Why are microbubble resorbers perferred choice for air removal?
Preferred when there is not enough room to install 18" of straight horizontal piping on the inlet side
154
A properly sized / placed expansion tank allows room for what?
Water to expand / contract
155
What are some factors that need to be considers when selecting an expansion tank?
(page 33)
1) total vol of water in the system
2) Min system temp
3) Max system temp
4) Min operating pressure
5) Max operating pressure
6) Presence of glycol in the system
156
Commercial / industrial hot water heating systems may require chemicals, why? (4 points)
1) Degrease the system
2) Inhibit corrosion
3) Lubricate components
4) Prevent freezing
157
What safety device is required on some hot-water boiler and all steam boilers?
A low-water cutoff (LWCO)
158
What does a Low water cut off do?
is a safety guard against low water condition in the boiler
159
What are common valves found in hydronic piping systems?
1) Gate Valves
2) Globe Valves
3) Ball Valves
4) Check valves
160
What valves are considered manual valves that can be used for isolation?
- Gate
- Globe
- Ball
161
Which valves will air flow freely through?
Gate or Ball Valves
162
How are Globe valves special?
- Provide throttling or isolation on feedwater lines
163
What type of valve is a Balancing valve / what is it used for?
- Globe valve
- Used for throttling flow in hydronic systems
164
Where can Check valves be used for?
Wherever reverse flow is unwanted
165
Water makeup to a boiler has 4 components, what are they?
(MBFB)
1) Main stop valve
2) backflow preventer
3) feedwater valve (pressure - reducing valve)
4) bypass valve (quick fill)
166
A dual check with atm port is considered what?
Backflow preventer
(seen on residential hydronic system)
167
A feedwater valve is also known as what?
Pressure - reducing valve
168
What is the working pressure of a PRV?
12 psig - 20 psig (84kpa - 140 kpa)
169
The backflow preventer is located where?
On the feedwater line in series w/ feedwater valve
(sometimes comes in a packaged unit)
170
Where is the purge valve located?
on the return piping near the boiler
171
PRV has a rating plate that identifies what?
- relief pressure setting
- relieving capacity
- size of valve
172
Where must the PRV be installed?
Directly on the boiler
173
Can there be another valve bn the PRV and boiler?
NO
174
How is water safely relieved on a PRV?
page 47
By discharging water through a pipe to a drain or safe location
175
Piping used for discharge outlet?
1) same size as PRV
2) as short as possible
3) sloped down / away from the valve to prevent a buildup of back pressure
176
What does a zone valve do?
permits or prevents the flow of water through the zone they control
177
What happens when a thermostat senses the need for heat?
Signal to control valve for that zone to open is sent
178
Zone valves are normally operated by what?
electric motors
activated by a 24 volt signal from thermostat in that zone
179
Zone valves are normally installed where?
On the supply side of each zone circuit
180
A balancing valve is a type of globe valve that has much less what?
flow restriction
181
How can you ensure accurate flow measurement at a balancing valve?
Install a straight pipe line a min 5 pipe diameters upstream of the valve + 2 pipe diameters downstream
182
A diverting valve is located where?
on the return side of the system similar to a mixing valve
flow coming into valve = return water from system
183
A 3 way diverting valve will divide what?
the cooler system return water into 2 flows
25% of the flow goes to the boiler to be reheated
75% bypasses the boiler to meet /mix w/ the heated water from the boiler
184
What is the difference bn a 3 way and 4 way mixing valve?
4 way mixing valve = can control water temp / flow rates --> supply piping / return piping to the boiler
185
What is the rule of thumb when it comes to BTU/h and circuit units?
No more than 60 000 - 70 000 BTU/h should be allocated to each circuit in the system
186
How many loops can there be in a split series loop system?
There can be more then just 2 loops
Heat source = sized to supply all the loops
187
How many pipe system is a diversion Tee or Monoflo system?
A one-pipe system
188
What principal does the Monoflo operates under?
page 66
Bernoulli's principal --> Where velocity is greatest, pressure is least
(operates via use of a venturi)
189
2 pipe systems are categorized as what? and where is this system foud?
1) direct or reverse return
2) found in large commercial or industrial buildings
190
Why is the direct return system unpopular for residential systems?
- Difficult to balance
- Expensive to install b/c of balancing components
- Expensive to maintain b/c of balancing components
191
The 2 pipe reverse return system is also called?
- First fed, last return system
- Most common system installed in commercial buildings
192
What are some benefits of a home-run system?
- Heat output of each room can be individually controlled (via flow rates)
- Water is delivered to each heat emitted at roughly the same temp
- Manifolds can be used in conjunction w/ variety of heat emitters
- Balancing vales can be used to regulate flow via each separate home run.
193
What does head loss mean?
pressure loss
194
How do circulators interact with each other?
through head loss
195
What is needed in order to create flow in a system?
a pressure differential
196
What happens if there is low flow resistance in a system?
very little head or pressure loss occurs
197
What is the main purpose of a primary circuit?
To keep a hot supply of water flowing through it.
Piping / pump need to be large enough to carry heated water / long enough to have space for the closely spaced tees for the secondary unit.
198
How else can hydraulic separation be accomplished?
By using a hydraulic separator or low loss header.
Both use a large diameter vertical chamber to slow down water flow rates.
199
Slowing water down does what?
- Creates little head loss via the chamber
- Creates hydraulic separation needed bn systems in order to be effective
200
What terms are used in a Hydronic system?
- supply main
- return main
- branch or spring piece
- riser
- runout
- stub
- drop
201
What can cause stress in a hot-water piping system?
- Fluid surges
- pipe misalignments
- impacts
- mvmt during earthquakes
202
How are stress impacts prevented?
- swing joints
- expansion loops
- expansion bellows
- oversized holes via building structures
203
What is another name for Swing Joint?
How do swing joints work?
- Spring piece
- allows for stresses / for grade
- consists of adding three or more elbows / connecting pipes w/in a piping run.
204
What kind of elbows are used in a swing joint?
90 degree or a combination of 90 and 45 degree
205
Pipes can expand which way?
in diameter + length
206
How do you allow for pipe expansion in holes either in walls or floors?
Drill all holes a min of 12mm (1/2" larger) than the size of pipe
The hole has to be sealed after to prevent air leaks / create fire stops
207
How can holes be sealed but still allow for movement?
Grommets or silicone caulk
208
Why must a system be entirely full of water?
So that a pump does not have to lift water, only move it
209
What is a zone?
a heating area that is controlled separately from other heating areas
210
True of False: Each zone has it's own thermostat.
True
211
What does zone controlled area allow for?
Greater comfort
Lower operating cost
Better temp control in building w/ areas difficult to heat
212
How does the orientation of a house determine the temperature of the rooms?
By which side the sun will hit / heat the rooms
213
True or False: Rooms on the southeast receive more sunlight than those on the southwest.
True, it's alll true
214
What type of material is good to use for radiant floor heating in different zones?
Concrete and wood --> allows for passage of heat but at different rates
215
How do high storeys require less heat than lower storeys?
Because of the stack effect
216
What is the stack effect?
Refers to the mvmt of heat upwards in a multi-storey building
(heat moves up elevator / staircases and through floors)
217
What are the different heat gain via windows based on direction?
North = no heat gain
South = significant solar heat gain
East = can contribute some heat gain
West = Also can contribute some heat gain
218
Why is balancing zones necessary?
1) To obtain design flow in the boiler
2) fluctuations in flow = reduce efficiency of heat transfer units / make control difficult
3) in order for zones to get heat flow
4) control loops necessary to make control valves work / make primary / secondary flows compatable
