Heating Flashcards
1
Q
Describe how a furnace works
A
Gas, oil or electricity transferred to air
2
Q
Describe how a boiler works
A
Water is the heat transfer medium
3
Q
What fuels are used for generating heat?
A
Oil, natural gas, propane, fossil fuels, wood
4
Q
Natural gas piping can be these materials
A
Steel, copper, or plastic
5
Q
Steel gas piping should be protected from rust by
A
Coatings or wraps/cathodic protection
6
Q
Risers that extend above grade should be
A
Metal
7
Q
What is typically laid with pipe to help locate it
A
A copper tracer wire
8
Q
Gas piping indoors can be these materials
A
Steel, copper, corrugated stainless steel tubing (CSST) coated with PVC
9
Q
Why might natural gas copper piping not be permitted in homes?
A
Sulphur in natural gas can react with it
10
Q
Natural gas metres can be inside or outside, but they need this
A
Isolating valves (shut offs)
11
Q
Natural gas piping vertical support is required
A
At every floor
12
Q
What do regulators on natural gas metres do
A
Discharge gas through a release event, 3 feet from sources of ignition, windows, doors, appliance, intakes, or exhaust, and 10 feet from mechanical intakes
13
Q
Where do shut off valves need to be for each natural gas appliance
A
In the same room as the appliances
14
Q
Describe natural gas appliance connecters
A
Flexible, metal piping or direct connection (unless earthquake prone)
2 to 3 feet long
Should not pass through walls, ceilings, floors
15
Q
Where should natural gas outlets be for a barbeques and fireplaces?
A
Outside the hearth and in the same room
16
Q
What should be installed where a natural gas horizontal pipe feeds an appliance and what is it called?
A
A sediment trap/drip leg
Called a dirt pocket
17
Q
Where is the natural gas usually bonded to?
A
Supply plumbing
18
Q
Is propane stored as a gas or a liquid
A
Liquid
19
Q
How high are propane tanks filled
A
80% capacity to allow for expansion
20
Q
Are propane tanks stored above ground or below grade
A
Either or
21
Q
What is a propane tanks location determined by
A
The size of the tank
22
Q
Where should propane tanks be stored?
A
10 feet from buildings and sources of ignition
23
Q
Why should propane tanks not be covered by roofs?
A
Relief valves discharge straight up
24
Q
Gas burners can be these gases
A
Propane or natural gas
25
Describe how burners operate
Fed from an electrically operated valve and mixed with air and ignited
26
Three most common burners.
Ribbon
Monoport
Ring
27
Describe a mono port burner
Newer burners
conversion gas burners
fan assisted
28
Describe two stage modulating furnaces
Low and high firing rate, rather than on and off. More efficient.
29
Which type of burners are especially prone to plugging with debris
Ribbon
30
How can rust happen in a burner?
If humidifiers or air conditioners above leak into furnace, or if exhaust gases condense
31
Natural gas needs a lot of air to burn. What are the consequences of restricted air
Condensation, costs, carbon monoxide poisoning
32
Describe burner flashback
Common on start up and with ribbon burners
Some ignited gas spilled out of the front of the heating system
33
What help prevent damage from burner flashback?
Heat shields
34
What is considered most of the brains of the heating system?
Gas valves. Electrically operated.
35
Describe the fail safe feature of gas valves
Fail in closed positions
36
Describe a heat shield
Metal plate that prevents flames from coming out of the front of the burner
37
Is a heat shield normally removed during home inspection
No
38
When should a specialist be called in regards to a heat shield
When there is evidence of scorching
39
Describe the three main ignition system types
Pilot, spark, or hot surface
40
What kind of pilot do older gas-fired heating systems have
A continuous pilot
41
What does a thermocouple do?
Make sure the pilot is on before allowing gas valve to open
42
Newer systems have what kind of pilot
Intermittent pilot that is ignited by a spark plug
43
What do high-efficiency systems use instead of a pilot
A hot surface ignition
44
Which burns hotter, oil, or gas
Oil
45
What kind of tank material is fuel oil stored in
Steel or fibreglass tank
46
Where are the fillpipe and vent pipes for oil?
Outside
47
What is required around oil tanks for spillage?
A Dyke
48
Why is an oil tank cylindrical?
To prevent from being blown over
49
Where can oil leaks occur?
In the tank, filter, oil, line
50
Where does rust occur in an oil tank and why?
At the bottom, because rust occurs due to condensation in the tank and water is heavier than oil
51
When should you keep an oil tank full and why?
In the summer to minimize condensation
52
Describe how oil burners work
Fan forces air into combustion chamber, pump forces oil into combustion chamber, nozzle converts oil into a fine mist, ignition ignites it
53
List the atomizing oil burner parts
Electrodes, nozzle, blast tube, or draft tube, primary controller, transformer/igniter, motor, fan, fuel pump
54
Describe combustion chamber refractory
Found in oil fired boilers and furnaces
Contains the flame in a controlled area
Similar material to fire brick
Protects other heating system components from flame
Located in the heat exchanger
Deteriorate over time and not easily accessible
55
Primary control does what and is located where
Prevents burner from operating if not safe
Mounted on exhaust or on burner
56
Newer burners use this for primary control
Cadmium sulphide eye or photocell
57
What is the risk of pressing the reset button in more than once on an oil burner
Can cause an accumulation of oil in a combustion chamber
58
What is dilution air also called
Draft air
59
What should be provided is a burner if in an enclosed room or a closet
Ventilation
(louvres in the furnace room door)
60
How much draft air and combustion air do you need to burn one cubic foot of natural gas any furnace?
15 ft.³ of each
61
What do natural draft appliances require?
Extra dilution, or draft air to ensure air moves up the chimney
62
What are the differences between oil burners and gas furnaces?
Oil burners, have a stronger fan that draws air in. Gas furnaces rely on natural draft. (newer have fans.)
63
Which tend to have more problems, gas furnaces or oil burners
Gas furnaces
64
How do high-efficiency gas furnaces bring in outside air
Directly through a pipe with pressure sensors
65
What is a draft hood also called
Draft diverter
66
Where is a draft hood usually found
In gas heating systems
67
What does a draft hood or draft diverter do?
Allows room air to be drawn into exhaust system to help exhaust move up the chimney
Cools exhaust air as it mixes
68
What is backdrafting or spillage
House, air pressure is lower than outdoor and exhaust gases spill out of the draft hood
69
Describe vent connecters
Galvanized steel pipe, 4 to 10 inches in diameter, sloped, quarter inch per foot
70
Vent connecter clearances from combustibles for gas and oil
Gas: 6”
Oil: 9”
71
Can modern high efficiency, gas systems be discharged in plastic pipes through the building rather than up the chimney and why
Yes. Because they remove so much heat.
72
What is the problem with a vent connector that is too long
They may cool gases and lead to condensation
73
What is the problem with undersized vent connectors?
Restrict flow of gases
74
What is the problem with oversized vent connectors?
May allow gases to linger
75
When should special vent connecter collars be used?
When passing through combustible materials
76
There have been recalls on these mid efficiency, Vents
High temperature plastic vents (HTPV’s)
77
What kind of chimneys are unsuitable for gas and why?
Unlined chimneys (exposed brick, or concrete). Condensing exhaust gases could damage the chimney.
78
Chimney liner can be what materials
Metal, clay tile, asbestos cement pipe
79
Where more than one appliance vents into a chimney, where should the smaller and larger vents be?
Smaller vent should be above the larger vent
80
Can attached houses share a chimney
Yes
81
Can chimneys have more than one flue
Yes. Each home can have 1 to 2
82
Where is deterioration common on masonry chimneys?
At the top where inside condensation occurs
83
If sand or pieces of brick are at the base of the chimney, what should be considered?
A liner
84
Can two appliances share a single flue and why
No. Exhaust from one can enter the home from the other.
85
Can a furnace and a fireplace share a flue
No
86
Chimney flues, without metal liners should have
A clean out door at the base to remove debris
87
What are the implications of buildup of debris at the bottom of a chimney?
It could block the flue and exhaust into house
88
What should be provided at each floor level around a chimney?
Fire blocking (noncombustible insulation)
89
Metal chimney vents for gas furnaces are what type and how much clearance do they need
B-vent. 1 inch clearance.
90
Metal chimney vents for oil furnaces are what type and how much clearance do they need
L-Vent. 3 inch clearance oil burns hotter.
91
Woodburning appliances need these wall systems
Triple wall systems. Higher temperatures than oil. 2 inch vent clearance.
92
If a metal chimney is 10 years old or older, why should it be inspected regularly?
Rust and gases can deteriorate inside of the chimney
93
What are the two types of bimetallic thermostats?
Mercury bulb, or magnet
94
Describe a bimetallic thermostat operation (mercury)
Central hub of coil is attached to temperature setting dial
Turning knob down means it Hass to get cooler for mercury to roll down and close contact
When warm, strip, tries to straighten out and mercury rolls away
95
Where should thermostats not be located?
In draughty areas, near heat, sources or areas that get direct sunlight
96
What is Maxximum set back on the thermostat and why?
Less than 10°F. Cooler temperatures create higher humidity which causes condensation.
97
Blowers usually run when the furnace is on, but why might they be continuously run?
For clearing house air
98
What can cause a thermostat to function improperly
Dirt, not level or not properly calibrated
99
What is a thermostat anticipator?
A device that prevents overshoot or short cycling and shuts off just before the temperature is reached
100
Furnaces use ducts. Boilers use
Pipes to move heated water to radiators
101
Describe a heat exchanger operation
Air is warmed as it passes over a hot metal box
102
What are the three main gas and oil furnace components
Heat exchanger, burner, blower
103
Should return registers be low or high and why?
Low on each floor, because cold air falls
104
What kind of gas furnaces are used above short crawlspaces
Downflow furnaces
105
What is an electric furnace similar to and why?
A hair dryer. Cool air is blown over a hot element.
106
Electric furnaces do not have these components
No burner, heat exchanger, or vent
107
A typical electric furnace element is how many watts
5000
108
What is a furnace sequencer?
A staged furnace that turns on heating element one by one and avoids electrical surge
109
How do auxiliary Plenum heaters work with furnaces?
They will try to heat the house until it can’t keep up then the furnace turns on
110
What is the most critical component of a gas and oil burner?
Heat exchanger. Separates house air being heated from burning fuel.
111
In the heat exchanger, burning fuel never comes in contact with house air. What is this called?
Indirect fired heating system
112
Modern heat exchangers have these to slow airflow and increase efficiency
Dimpled or curved surfaces
113
Average life expectancy of a heat exchanger
18 to 25 years
114
Potential causes of rusted heat exchangers
Defective, humidifiers, leaking condensate trays from air conditioning, moisture from damp basement
115
When is a specially protected heat exchanger recommended
When swimming, pool chemicals, paint, strippers, chemicals, and hair salons can cause rust
116
What is part of regular maintenance for a heat exchanger?
Flushing
117
Motors for blowers can be mounted internally to drive it directly. How do external motors operate
They drive the blower with pulleys and a belt
118
What does an ECM stand for?
Electronically commutated motors
119
Why are electronically commutated motors more efficient?
Larger range of operating speeds
120
What does PSC stand for?
Permanent split capacitor motor
121
Are permanent split capacitors more or less efficient
Less
122
Most common problems with blowers or blower motors
Burnt out motors or worn bearings
Dirt buildup causing vibration, blower becomes loose, bearings fail
123
Describe the functions of a fan/limit switch
Keeps fan blowing after burner is shut off until air feels cool
Shut off burner if furnace overheats
124
When can short cycling occur?
When the fan limit switch is out of adjustment or thermostat and exchanger problems
125
What could happen if the limit switch is too high?
It could overheat and ignite dust inside ductwork
126
Describe an older furnaces pilot
Continuously burning that ignites gas when main valve opens
127
What is a thermocouple?
A heat sensor that verifies the pilot is on
128
What is hot surface ignition? Also called.
Electronic ignition
129
What is a form of primary control?
Heat or flame sensors
130
Oil burners are typically spark ignited. What does primary control do?
Heat or flame sensors stop the dumping of fuel
131
Why does condensate from burners need to be neutralized before entering drains?
It can be slightly acidic from combustion gases
132
Some furnaces have this to detect gases, escaping out of the front of the burner
Is spillage switch
133
What is it called when gases escape out of the front of the burner
Backdrafting
134
What is an air proving switch also called
A differential switch
135
What does an air proving switch or differential switch do?
Senses pressure differential across the fans in furnaces with induced draft fans
136
Where do air filters sit
In the return air Plenum, upstream of the blower
137
Where is filter support?
On the blower side of the air filter
138
Why are electronic filters better?
They can remove pollen and cigarette smoke particles by electronically charged plates of opposite polarity
139
What kind of noises are normal on electronic filters?
Sparking or crackling noises
140
What kind of filters help absorb odors?
Activated, charcoal, filters down stream of electronic filter plates
141
Which direction should the arrow on a filter point
Arrow indicating airflow should point to the blower
142
Some furnaces may have this to combat winter air
Humidifier
143
Describe a drum type humidifier
Mounted on return air duct with a bypass duct to supply Plenum
Should not be directly above heat exchanger
144
What is a trickle humidifier also called
Cascade
145
What is a trickle humidifier do
Allows water to fall over a special pad. High-quality.
146
These humidifiers are rarely seen residentially
Atomizing and steam generating
147
Why might a drum humidifier tray overflow?
Mineral deposits clogging water supply valve
148
What is needed if an air conditioning unit is connected to the furnace to prevent AC coil ice up due to short circulating of airflow
A humidifier duct damper
149
Where should a humidifier be installed in a furnace?
On the return duct, not the supply Plenum above the heat exchanger
150
Where are return air registers often located
In hallways and stairwells
151
Where should supply registers be located?
And your exterior walls, below windows, and return opposite (warm wall)
152
What should rooms without a return register have
A 1 inch gap for air flow to return
153
Does supply or return air duct work accumulate debris
Return
154
What is a simple way to improve heating in a room
Blocking off a return register
155
Where should supply or return air grills not be and why?
In garage is, as fumes may be drawn into the house
156
Slab on grade houses with forced air often have ducts embedded in the foundations. What can be the problem with this?
Can collapse when poured or fill up with water
157
Up until the 70s all systems were similar efficiency. What was the general operating steady state efficiency
80%
158
When a conventional furnace is not operating, what is happening
Warm house air is escaping of the chimney just maintaining adequate draft for exhaust gases
159
On gas fired systems, how is some fuel wasted
By keeping the pilot on
160
Average seasonal efficiency of a boiler or furnace
55 to 65% for conventional
161
Describe mid efficiency furnaces
They have a secondary heat exchanger, but are mostly conventional systems with modifications to reduce off cycle losses (draft fan in exhaust)
162
What does SEER stand for?
Seasonal energy efficiency ratio
163
High-efficiency furnaces are also known as
Condensing furnaces because exhaust gases condensate from being so cool
164
One of the main products of burning natural gas is
Water
165
High-efficiency furnaces have this many heat exchangers
2 to 3
166
High efficiency furnaces are this efficient
90% or more
167
How do combination heating systems work?
They use the water heater to heat the house. hot water flows to the plumbing system or to a fan coil unit. The fan blows air across the coil with hot water.
168
Water from a boiler can heat the home through these outlets
Radiators or radiant floor heating
169
Combination heating systems can also be used to heat the water in the tank. What is this called?
Indirect systems
170
What is the issue with combination heating systems?
Modest capacity. Many are undersized for homes.
171
What are used if a combination system is to be operated at high temperatures
Tempering valves
172
What is the issue with ductwork in regards to combination heating systems?
Most homes are not designed to handle these high volumes of air, and they have reliability problems
173
Life expectancy of combination heating systems
5 to 10 years
174
Hot water boilers are also called
Hydronic heating
175
How do you hot water boilers work?
The heat by moving hot water through pipe loops
176
Where is the heat from the hot water boiler distributed
At radiators, convectors, baseboards
177
Do hot water boilers, boil water
No, sir.
178
What are the three components of a hot water boiler?
Burner, heat exchanger, and pump
179
Electric hot water boilers have this rather than the heat exchanger
Electric heating elements
180
Older systems of hot water boilers, relied on gravity and convection. What do newer systems use?
A circulating pump
181
Modern boilers are closed. Systems and water is under pressure. What do they require?
An expansion tank for pressure build up
182
Describe when an expansion tank gets waterlogged?
Air in the expansion tank gets absorbed into water, and the tank has to be drained
183
What do expansion tanks have to ensure no air absorption?
Diaphragm or bladder that separates water and air
184
What is the definition of waterlogged?
When an expansion tank has no air and it can’t accept more water
185
Describe a pressure reducing valve
Connects boiler to plumbing
If pressure drops below 15 psi, it allows water in
Backflow preventer stops water from system into house plumbing
186
Describe a low-water cut out
In large boilers, it shuts off heat when water levels are too low
187
What are the 3 operating and safety controls for 1) high temperature and 2) pressure and for 3) when the water levels are too low called
High temperature limit
Pressure relief valve
Low-water cut out
188
These radiators are common in older homes
Cast-iron radiators
189
What are an alternative to radiators?
Hot water convectors
190
What are convectors
Cast iron, copper tubing with aluminum fins. Take up less space than radiators.
191
Baseboard hot water distribution systems can be these materials
Steel, copper, polybutylene
192
What happens when an a radiator has air trapped in it
It will not fill with water and not heat properly
193
Trapped air in a radiator can be released through this
A bleed valve
194
What may resolve heating issues with radiators and convectors?
Adding more water by adjusting the water make up valve
195
Why does cast iron result in more even heating?
Takes more time to cool down and heat up
196
What can be placed behind radiators to help direct heat?
Reflective materials. Aluminum foil faced insulation boards.
197
Piping on most hot water heating systems is black steel non-galvanized. Modern systems may be these materials.
Copper, plastic piping, polybutylene, or crosslinked polyethylene (PEX)
198
Is draining water from a radiator every summer recommended
No. Pipes will deteriorate quicker.
199
What material has problems with plumbing/fittings, but not so much with hot water heating
Polybutylene
200
Why is polybutylene piping to a baseboard convector not good practice
Can connections may leak due to pressure
201
What are zone valves?
Motorized valves for areas controlled by different thermostats
202
Thermostats can control these for radiators in different zones
Different circulating pumps
203
Radiant, hot water system piping can be where
In floors are ceilings, which radiate heat into rooms
204
Radiant, hot water system piping in concrete should be how far below and how far apart
3 inches below concrete and 4 to 12 inches apart
205
Which temperatures are higher or lower, radiant heating systems OR radiator/convector systems
Temperatures in radiant, heating systems are lower
206
What is a home run in the boiler system?
Discrete loops, feeding different parts of the home from a single manifold at the boiler
207
What materials are used in a radiant, hot water system?
Polybutylene and PEX
208
Radiant, hot water systems can be damaged by
Building settlement
209
How does rust occur in a radiant, hot water system?
Non oxygen barrier polybutylene may pass oxygen into boiler water
210
Seasonal boiler efficiencies
Conventional
Mid
Conventional 60%
Mid 80%
211
Boiler life expectancies
Mid cast iron
Mid steel
Mid copper
Mid cast iron: 25 to 50 years
Mid steel: 20 to 35 years
Mid copper: 15 to 25 years
212
Unlike hot water heating, steam boiler radiators and piping are this when at rest
Filled with air
213
Describe the operation of the steam boiler
When steam is generated, air is displaced and released through vents in a radiator or piping
214
What happens when steam hits radiators
It condenses, and it is returned to the boiler to be reheated
215
Describe one pipe steam boiler system
Single pipe on each radiator, condensate fluids, back through the same pipe
Needs a second pipe to be converted into a hot water system
216
Can the hot water system be one pipe?
No. Needs to be two
217
Describe a two pipe steam boiler system
One pipe for steam, one pipe for condensate
218
What components do steam boiler radiators have
Control valves and air vent or steam traps
219
What is a steam boiler pressuretrol?
Operating device and safety device
First device that should shut off the burner with rising steam pressure
220
Describe a low-water cut out on a steam boiler
Externally mounted, and have a blow down valve for monthly testing
221
What discharges steam on a steam boiler
Pressure relief valve
222
What is a Hartford loop and equalizer pipe in a steam boiler?
Prevents water level from dropping as a result of a leak in a return pipe or pressure in balance between supply and return
223
What happens if a pipe slope is incorrect in a steam boiler system
The system can be noisy and heat unevenly
224
What is the rule with draperies around electric heat?
Should be kept 8 inches above heaters or 3 inches in front if 1 inch above the floor
225
What should not be located above electric heaters?
Receptacles. Cords may touch.
226
What is the shadow effect in electric radiant heat?
Radiant heat works like sunlight, so it feels cool in the shade
227
Five common components in central heating systems
1. Thermostats.
2. Burners.
3. Heat exchangers.
4. Pipes or ducts.
5. Outlets (radiators or registers.)
228
Gravity hot water systems rely on what to move water
Convection
229
There must be a working space of how much in front of service end of the furnace
30 inches
230
Minimum clearances on central heating system, should be found where
Nameplate
231
Gas fireplaces that are not direct vent must not be installed in
Bedrooms, bathrooms, closets
232
Furnaces may be in the garages if
Protected and isolated from combustibles
233
Heating sources that generate a spark/flame/glow must be where in the garage
18 inches above garage floor because fumes tend to collect on near floor
234
When can a heating appliance be installed on the garage floor?
When it is enclosed in a separate compartment with exterior access and combustion air is drawn from outside the garage
235
What are the requirements for attic furnaces
Should be within 20 feet from access opening with the opening being 22 to 30 inches
24 inches wide solid floor to access opening
236
Size and number of outlets depend on
House square footage, climate zone, furnace capacity, seal insulation
237
Rooms larger than this need two or more outlets
150 ft.²
238
What devices can help achieve balance in a heating system?
Dampers inside ducting or throttling valves in hot water heating systems
239
How did heat rise in an old warm air heating system?
Gravity fed without a fan
240
What does AFUE stand for?
Annualized fuel utilization efficiency
241
Condensing furnaces use this to extract more heat from the flue
The second heat exchanger
242
Condensing furnaces require what to exhaust combustion gases, and why
A forced draft because the cool gases don’t rise very quickly. So they can be vented horizontally
243
Approved materials for gas piping
Rigid galvanized steel, rigid black steel, CSST flexible, gas tubing
244
Not approved materials for gas piping
Cast iron, copper, brass, aluminum (exceptions are made for copper and brass tubing for natural gas with low amounts of hydrogen sulphide)
245
Copper connecters for natural gas may be subject to corrosion from
Sulphur compounds
246
Why are aluminum tubing connections not recommended for natural gas?
They are soft and tend to leak
247
Why does warm air displace cool air in a room which returns to the furnace?
Warm air takes up more space and exerts more pressure
248
In some older homes, these are in place rather than return air ducts
A Plenum in a wall or floor cavity
249
What is the safety implications of having no return ducts
Return air may contain combustion gases.
250
Gravity, fed systems typically feature large furnaces with
Oversize ducts sticking out of the top of the housing (octopus)
251
Why do gravity fed systems often lack air filters?
Because the airflow is so sluggish, a filter may stop it
252
A gravity fed system is also called
Octopus furnace
253
An octopus furnace will probably be wrapped with what and require what
Wrapped with asbestos and require a hazmat assessment
254
Describe a forced air heating system
Furnace with a burner that heats a heat exchanger, vent flues, blower, fan, supply, return
255
Blue flames in burners indicate
Hotter and complete combustion
256
Flame deflection or movement inside a burner or smells may indicate
A cracked heat exchanger
257
What does soot in a burner indicate
Incomplete combustion
258
Heat exchangers contain the burner, flame and directs
Fluegases to vent pipe
259
What causes heat exchanger metal fatigue, and cracking?
Each time the exchanger heats , metal expands, and contracts
260
A cracked heat exchanger could cause
Levels of carbon dioxide and carbon monoxide
261
Most furnaces that have been used over how long are in efficient and should be replaced
20 years
262
Three main thermostatic switches
Thermostat, fan control, high limit control
263
Thermostat should be installed how to work correctly
Clean, level, securely mounted
264
What is short cycling?
When the fan control setting is to close and turns off and on rapidly
265
What happens when the thermocouple at the pilot cools?
Pilot safety control valve shuts off the gas flow
266
Fuel oil fired systems use what switches
Buy metallic stack switch or a photo electric cell
267
Glow plugs or hot surface ignition systems require
Ignition proving devices
268
Forced air heating systems must have adequate separation between
Combustion and recirculating air to operate properly
269
The opening to a return air duct should be 10 feet from
Furnace firebox, and draft diverter
270
Furnaces in sealed areas Need openings where?
Within upper 12 inches and lower 12 inches of enclosure
271
Dust or dirt along furnace compartment door edges indicates
Low pressure and insufficient combustion air
272
In larger rooms of ordinary tightness, space it’s self can provide combustion air unless
Other fans use that air. It can cause negative pressure and pull in combustion gases.
273
Inspections should include the blower fan compartment. If it is older, what should you do?
Turn off the master shut off switch. Modern furnaces have automatic disconnect switches.
274
If a blower access door is loose or missing, what could happen
Flue gases could be drawn into the blower
275
Older furnaces have these motors that require lubrication and belts adjusted
Squirrel cage fans with blower motors
276
Do modern furnaces need lubrication
They are self lubricating, and do not have belts
277
Blower noises could indicate
Worn bearings or a loose fan belt
278
Air filters should be checked how often and changed how often
Checked monthly and changed, or cleaned twice annually
279
Air filters prevent this on AC units
Dust accumulation on evaporator coils
280
These disposable electrostatic filter are 3 to 4 times larger and need replacing less
Pleated
281
These filters are very thick and very efficient
Media filters
282
After removing the air filter, where should you look and for what?
Look into the Plenum for dust and asbestos (gray or white paper tape)
283
Air return ducting, and Plenum should be
Airtight
284
Furnaces on concrete floors, or wood platforms might have gaps between
Furnace and plenum floor which can cause spillage or mixing of supply and combustion air
285
2 supply configurations for forced air heating systems
1. Radial distribution system in which each branch runs from the furnace.
2. Extended Plenum system with rectangular duct as a trunk line with branches.
286
Furnace plenums should be at least how high above ground
4 inches above ground
287
Sheet metal and rigid fibrous ducting need support every
6 feet
288
Soft ducting should have this every 4 feet
Galvanized strapping
289
Air flowing over asbestos tape in a heat register have what implications
May circulate fibres through the house. Recommend any asbestos in the airflow be abated.
290
If supply registers have dark soot deposits what may it indicate
Cracked heat exchanger, or a faulty draft
291
What can help homeowners lower consumption?
Humidifiers because moist air feels warmer
292
Combustion produces
Water vapour and toxic gases
293
Six venting methods for heating appliances
1. Terra-cotta lined masonry flus or rigid, cement, asbestos flues (transite)
2. Type B, Vents typically double wall metal vent piping.
3. Type BW Vents, oval shaped type B Vince designed for above wall furnaces
4. type L vents for fuel oil fired appliances.
5. Plastic PVC pipe fence for high-efficiency condensing appliances.
6. Integral vent assemblies for a direct venting.
294
Venting materials that heat up slowly may restrict the upward flow of fluegases due to the cooler temperatures. What is recommended?
Galvanized Steel vent piping
295
These clothes dryer vents are not approved
Ungalvanized, blue metal and aluminum vent piping
296
In the metal and masonry vents, should the vertical or horizontal portion be longer
Vertical should be 1/3 longer than the horizontal portion. Prevent spillage.
297
What vent pipes are considered vertical
45° angles and beyond
298
Vent dampers must be designed to prevent the burner from
The burner from firing up when in closed position
299
Flus or vent connecters are connected to
A draft hood at the furnace
300
A rusted or discoloured draft hood could indicate
Spillage (unburned gases)
Backdrafting
301
Dampness at the draft hood can indicate
Spillage. Placing mirror there, to see if it fogs.
302
Hot water and steam heating systems are also called
Hydronic heating systems, because both use water for heat
303
Are hot water or steam heating systems efficient
Steam systems are not efficient. Heat is slow to arrive.
304
How is a steam boiler distinguishable from the hot water boiler?
Buy a site glass or level gauge, which shows the water level inside the boiler
305
In a steam boiler, the upper water edge of a level is called
Meniscus. It should be in the upper part of the sight glass when cold.
306
Steam systems have what kind of valve that replenishes the boiler
Float valve
307
What is a pressure control valve also called
Pressuretrol
308
Banging radiator noise in a steam heating system can be caused by
Steam blocked by water ponding in the pipes. Shimming the radiator to slope downward to the inlet pipe usually resolves this.
309
Where do gravity, hot water systems have an expansion tank?
In the attic. Should have a relief valve on the boiler
310
Leaks on a new boiler in the snow belt may have been caused by
Frozen water piping due to a fuel line that got clogged or a fuel tank that didn’t get refilled
311
Boiler temperature is measured by
And aquastat. Turns fuel on or off.
312
What is internal boiler pressure measured by that’s indicated by a gauge
Altitude
313
What are common causes of excessive boiler temperature
Stuck fill valve, water exchange coil leak, ruptured expansion tank, waterlogged expansion tank
314
Where should circulating pumps be installed in a hot water or steam heating system?
On the distribution return pipe just before the boiler
315
What is a draft hood also called
A draft diverter
316
Floor room heaters should be supported on
Concrete slabs 3 inches above ground or suspended 6 inches above ground
317
A gas fired appliance vent should vent where on the roof
2 feet above the roof, and 2 feet higher than any portion of the building within 8 feet
318
These furnaces have special double horizontal vents
Direct vent wall furnaces
319
Where should gas fireplaces terminate?
At least 4 feet from a door or window. Or 1 foot above they do not require a vent pipe that extends above the roof.
320
Do gas fireplaces need to be vented above the roof
Nope
321
Where is a central AC typically installed in the split system
With condenser at the building exterior and the evaporator adjacent to the interior furnace equipment
322
Some central AC units have electric heaters for
Keeping lubricating oil from absorbing refrigerant
323
Outside temperatures should be at least what to operate central AC
65°F
324
How do you check the running load amps on the central AC
With an ammeter
325
Where will you find the normal RLA on a central AC
Equipment ID plate
326
A reading of what percentages of RLA is normal on central AC units
60 to 90%. More indicates refrigerant, overcharge, or bad compressor.
327
A defective compressor or low, refrigerant central AC will give what reading
A low RLA reading
328
Where should a central AC condenser be regards to the ground
4 inches above
329
Frost on central AC lines or coils could be from
Insufficient airflow. Filter debris
330
What is another function of AC?
Dehumidifying
331
AC condensate may be discharged into a laundry tub if
Proper air brake is maintained
332
What is suggested to reduce cold air loss in central AC
A trap
333
If a furnace or evaporator unit is installed in an attic above a finish the ceiling, what is required
A secondary condensate line
334
Where should AC evaporator coils be located?
On the downflow side of the heat exchanger
335
Describe heat pumps
Like an AC that extracts heat from the exterior and move is it inside or extracts from inside and out puts outside
336
Two types of heat pumps
Air to air
Water to air (geothermal)
337
Main difference between a heat pump in AC
Reversing valve that changes direction of refrigerant flow
338
Heat pumps have an accumulator to
Keep refrigerant from entering compressor
339
Metering devices on heat pumps do this
Controls refrigerant that flows the coils to absorb heat
340
What are the rules to inspecting a heat pump?
Inspect using thermostat control only. No change in heating or cooling mode.
Should be energized 24 hours before operation
341
What is passive distribution?
Gravity furnaces. (octopus.)
342
Describe the ducting and registers on a gravity furnace
Several registers on one duct, on inside walls.
One cold air return on main floor near outside wall
No fan or filter
343
What is power distribution?
Forced air heating
344
Is a baseboard heater is 100% efficient
Yes, but the voltage drop is not
345
Describe a BTU
British thermal unit. Amount of heat required to raise the temperature of 1 pound of water by 1°F.
346
Three ways of heat transfer
Radiation, conduction, convection
347
What does the draft hood do?
Pulls dilution room air into vent to push warm products of combustion out
348
What should you look for on any gas appliance?
A drip leg
349
Describe mid efficiency heating system
Induced draft fan pushes exhaust gases out and pulls combustion air in
Forced draft, then pushes air into burner
350
Induced draft fan and forced draft fan. Which pushes and which pulls
Induced pulls combustion air in. First draft fan pushes air into burner.
351
Where is the blower on a high-efficiency gas furnace?
At the top
352
What can be the problem with adding a high-efficiency system?
Conventional furnaces, ran hotter, so duct work with size for that. Using a high-efficiency in place might not heat as quickly so it has to run longer.
353
Describe a Plenum
Last spot where heated air hits before ductwork
354
What is a pressure gauge on a boiler also called
And indicator
355
What is the boiler system damper called
Barometric damper
356
Fuel fired heating should be serviced
Annually
357
Radiators have these two things on them
Thermostatic valve and an air vent
358
What is floor heating also called
Thermonet
359
Describe a district heating system
Biomass plant feeds a community with heat. Usually steam.
360
Describe geothermal heat
Heat pump from the ground. Hot Springs etc..
361
Ways of heat generation
Combustion, electric resistance, refrigeration (heat pump)
362
And in adequate amount of this can lead to carbon monoxide
Combustion air
363
Is return air the same as combustion air
No. They are separate. Look for combustion air supply. (grill on door, high and low.)
364
Can freestanding, natural gas, stoves, be in living rooms
Yes. But not in the bedrooms.
365
Gas regulators have these inside
Diaphragm and vent
366
What is an opening in a Plenum and what does it do?
A spill grill. Allows air to be pushed out of Plenum for Burner
367
On a mod number, how many BTUs if it says 75
75,000 BTUs
368
On a serial number if it says 9111 what does that mean?
Made in 1991 in November
369
If a dryer or other appliance is in the same room as a furnace, how should you operate them?
With the door closed and test for proper combustion air and possible Backdraft
370
What is a humidifier made in the cooling season and why
A bypass damper. Short circuiting through humidifier can ice up the coil.
371
Do you want to dehumidifier in the summer or winter and why?
Dehumidifier in the summer. Cooling air inside the house = relative humidity rises and air becomes damp. If not AC coil might be iced up
372
Describe a B vent
Do a wall so less clearance is needed
373
Is it OK to smell gas around a meter?
Yes. Regulator is releasing small amount.
374
What kind of connections on a natural gas metre do you want to see?
Flexible in case the house moves
375
What is the wire on a gas line to the metre for?
A tracer to locate
376
What kind of metal is on gas meters?
Painted black steel
377
What sits on the floor and prevents cool air from spilling out?
Cold combustion air diffuser
378
What is flame rollout?
Flames can come out of the front of the device from backdrafting
379
Vent connecters need to slope
Up
380
What does corrosion on a heat exchanger indicate
Acidic condensation gases, running back down flue
381
What do flames wavering indicate?
Cracked heat exchanger
382
What is a tail pipe?
Transfer pipe between primary and secondary combustion
383
What is the secondary heat exchanger also called
Exhaust de coupler
384
How many cubic feet for every thousand BTUs of combustion air
50 ft.³
385
Every thousand feet above sea level, derate BTUs by
4%
386
The primary control fire eye is also called
Cadmium photocell
387
What is located in an oil furnace in a refractory that provides flame
Blast tube
388
What is the ceramic combustion chamber at the burner also called
Fire pot or refractory
389
What would be considered the brains of the furnace?
Electronic control board
390
Primary control at the vent connecter is also called
Stack relay
391
What does the barometric damper do?
Regulates chimney draft
392
What does an aquastat do?
Controls, circulating pump, and high temperature in limit switch
393
Is it OK to see water at a boiler?
Yes. Pressure relief valves can do this.
394
How much clearance for boilers?
18 inches
395
Chimney Capps should be
Concrete and overhang
396
This converts DC to AC
Inverter
397
Solar backfeed Maxximum in a panel
20%
398
Where should the photo voltaic AC disconnect to be?
At the metre
399
What is a material defect mean?
Financial or safety problem
400
This indicates that it is a closed system boiler
Check valve (Tpr)
401
NOT required to inspect
Heat exchanger
Humidifier
Electronic air filter
Solar space heating
Determine heat supply adequacy or distribution balance
402
Difference between mid efficiency and conventional furnace
Induced or forced draft fans
403
Difference between mid efficiency and high
Secondary heat exchanger
404
Where is the induced draft fan and forced draft fan
Induced= after heat exchanger, before vent. Pulls air
Forced= before burner, pushes air
405
Natural draft fans are also called
Atmospheric
406
High efficiency furnaces have this exhaust characteristic
Slow. Pull out as much heat as possible
407
What can rust around a draft hood indicate
Back drafting
408
What is make up air
Outside air into heating ducts
409
Danger of operating furnace without fan cover
Negative pressure
410
Airflow in a drum type humidifier direction
From supply to return. Sensor in cold air return
411
Report must describe
1
2
1) fuel or energy source
2) heating method
412
Warm air rising off the pavement on a hot day would be heat transfer by
Conduction
413
Vent connecter should be in regards to length
As short as possible
414
Three things that cause friction loss in duct systems
Long length, elbows, dirt
415
Describe the sequence of operation of conventional gas furnace
Call for heat
Sense the pilot
Turn on gas
Since the temp of air and heat exchanger
Turn on blower
Thermostat satisfied
Turn off gas
Since the temp at heat exchanger
Turn off blower
416
The furnace vent discharging below the soffit will
Cause warm, moist exhaust to go up in the attic
417
Three problems induced draft fans may have
Corrosion, seized, cracked, electrical malfunction
418
Three problems oil burners might have
Clogged, leaking, fail to ignite
419
Two advantages of a water heating system
Easy zone control, maybe integrated with house water system
420
Heat exchangers separate
The combustion air from house air
421
A mid efficiency induced draft gas furnace is manifolded with a natural draft water heater. Is this a concern?
Not if the vent is large enough to handle both
422
If a heat exchanger fails in a conventional efficiency furnace, will there be soot build up on the burner side of the heat exchanger
No
423
Define relative humidity
How full of water the air is relative to the maximum amount of water you can hold at a given temperature
424
Define relative humidity
How full of water the air is relative to the maximum amount of water it can hold at a given temperature
