OBT 2 Mohawk Exam Questions with
Complete Solutions 2026.
About _____________ cubic feet of air is required to ensure complete combustion of one [1]
gallon of #2 fuel oil. - Answer 2000
T/F? Air supply openings that communicate with the outdoors of a building must be located not
less than twelve [12] inches above the outside grade level. - Answer True
An oil-fired boiler with an input of 0.75 USGPH that is vented into a clay lined masonry chimney
20 feet high must maintain a minimum base temperature of ____________ °F. - Answer
320°F
A furnace rated at 0.75 USGPH is connected to a twenty [20] foot high clay tiled lined masonry
chimney. The thermal resistance is R2. Using the B139 code book vent tables, determine an
acceptable vent diameter range. - Answer 4 to 5 Inches
T/F? The minimum distance a vent can terminate from a gas utility service regulator is one [1]
foot and from the regulator's vent outlet is four [4] feet. - Answer False
A single wall vent connector on a furnace with a draft regulator should never be installed in an
unheated space; furthermore, an appliance's vent connector passing through an unheated
space must be a ______________________ vent. - Answer double wall or insulated
T/F? A single wall vent connector with a vent temperature not exceeding 750 °F must be at least
three [3] inches away from combustible materials. - Answer False
An oil venting system shall terminate from a building mechanical air inlet, or operable window
or door by no less than _____________________________ feet. - Answer 6ft
T/F? An unlined masonry chimney, correctly sized and in good condition, may accommodate a
new oil-fired appliance. - Answer False
The essential elements of a building are the - Answer building envelope, occupants,
mechanical systems and external environment
Building skin is required to - Answer protect the underlying materials
, T/F? If the heat loss of a building is 50 000 Btu/h, the furnace to be selected should have an
input of 50 000 Btu/h or more. - Answer False
The best way to remove dust from a building is to - Answer filter the air or exhaust it
mechanically
T/F? The most effective way to reduce heat loss is to seal air leaks around the windows using a
caulking gun. - Answer True
T/F? The purpose of a heating appliance is to heat the occupants in a building. - Answer False
Negative pressure in a building can be caused by a[n] - Answer lack of makeup or combustion
air
T/F? Evaporation increases the rate of heat transfer. - Answer True
T/F? Occupants will experience higher heat losses as a result of greater air movement. e.g. from
fan blowing air - Answer True
T/F? Occupants will experience lower heat losses as a result of higher humidity levels in a
heated building. - Answer True
The best location to install a forced air furnace is
__________________________________________________________________. - Answer
near an outside wall in a central location in an unfinished basement under the kitchen
T/F? Make-up air does not replace air being exhausted [or lost] by a building. - Answer False
If one of your customer's fuel-oil bills increased greatly this winter, the cause may be that
______________________________. - Answer the system needs an annual maintenance,
there's a leaking storage tank or significant renovations / changes in building structure
The recommended domestic hot water temperature setting for most residential-type water
heaters, unless otherwise stated by provincial building codes, is _____________ °F. - Answer
130°F
On a storage type direct fired water heater, the temperature/pressure relief valve is set to
relieve at ___________ psig. - Answer 150 psig
Complete Solutions 2026.
About _____________ cubic feet of air is required to ensure complete combustion of one [1]
gallon of #2 fuel oil. - Answer 2000
T/F? Air supply openings that communicate with the outdoors of a building must be located not
less than twelve [12] inches above the outside grade level. - Answer True
An oil-fired boiler with an input of 0.75 USGPH that is vented into a clay lined masonry chimney
20 feet high must maintain a minimum base temperature of ____________ °F. - Answer
320°F
A furnace rated at 0.75 USGPH is connected to a twenty [20] foot high clay tiled lined masonry
chimney. The thermal resistance is R2. Using the B139 code book vent tables, determine an
acceptable vent diameter range. - Answer 4 to 5 Inches
T/F? The minimum distance a vent can terminate from a gas utility service regulator is one [1]
foot and from the regulator's vent outlet is four [4] feet. - Answer False
A single wall vent connector on a furnace with a draft regulator should never be installed in an
unheated space; furthermore, an appliance's vent connector passing through an unheated
space must be a ______________________ vent. - Answer double wall or insulated
T/F? A single wall vent connector with a vent temperature not exceeding 750 °F must be at least
three [3] inches away from combustible materials. - Answer False
An oil venting system shall terminate from a building mechanical air inlet, or operable window
or door by no less than _____________________________ feet. - Answer 6ft
T/F? An unlined masonry chimney, correctly sized and in good condition, may accommodate a
new oil-fired appliance. - Answer False
The essential elements of a building are the - Answer building envelope, occupants,
mechanical systems and external environment
Building skin is required to - Answer protect the underlying materials
, T/F? If the heat loss of a building is 50 000 Btu/h, the furnace to be selected should have an
input of 50 000 Btu/h or more. - Answer False
The best way to remove dust from a building is to - Answer filter the air or exhaust it
mechanically
T/F? The most effective way to reduce heat loss is to seal air leaks around the windows using a
caulking gun. - Answer True
T/F? The purpose of a heating appliance is to heat the occupants in a building. - Answer False
Negative pressure in a building can be caused by a[n] - Answer lack of makeup or combustion
air
T/F? Evaporation increases the rate of heat transfer. - Answer True
T/F? Occupants will experience higher heat losses as a result of greater air movement. e.g. from
fan blowing air - Answer True
T/F? Occupants will experience lower heat losses as a result of higher humidity levels in a
heated building. - Answer True
The best location to install a forced air furnace is
__________________________________________________________________. - Answer
near an outside wall in a central location in an unfinished basement under the kitchen
T/F? Make-up air does not replace air being exhausted [or lost] by a building. - Answer False
If one of your customer's fuel-oil bills increased greatly this winter, the cause may be that
______________________________. - Answer the system needs an annual maintenance,
there's a leaking storage tank or significant renovations / changes in building structure
The recommended domestic hot water temperature setting for most residential-type water
heaters, unless otherwise stated by provincial building codes, is _____________ °F. - Answer
130°F
On a storage type direct fired water heater, the temperature/pressure relief valve is set to
relieve at ___________ psig. - Answer 150 psig
