IRC Mechanical Code 2009 Questions and Answers
In order for someone to service an appliance other than a room heater, a minimum working space
of______ inches deep by 30 inches wide shall be provided in front of the control side of the
appliance. ** Answ** 30
M1305.1
For the purpose of providing working space, a furnace or air handler located within a closet or
similar compartment shall be provided with a minimum of ______ clearance along the sides,
back and top of the appliance, with the total width of the enclosing space a minimum of
______wider than the furnace. ** Answ** 3 inches, 12 inches
M1305.1.1
A minimum ______ working space shall be provided along the front combustion chamber side of
a central furnace having a firebox open to the atmosphere. ** Answ** 6-inch
M1305.1.1
Where an appliance is installed in a compartment accessed by a passageway, the passageway
shall have a minimum unobstructed width of ______, but not less tham necessary to allow
removal of the largest appliance in the space. ** Answ** 24 inches
M1305.1.2
Where an appliance is installed in an attic, the clear access opening shall be a minimum of
______, but in no case less than necessary to allow removal of the largest appliance. **
Answ** 20-inches by 30-inches
M1305.1.3
Appliances suspended from the floor shall have a minimum clearance of ______ from the
ground. ** Answ** 6 inches
M1305.1.4.1
,Excavations for appliance installations shall extend a minimum depth of ______ below the
appliance with a minimum clearance of ______ on all sides except the control side. ** Answ**
6 inches, 12 inches
M1305.1.4.2
Where ventilated air space is used to reduce the required clearance between an appliance and
unprotected combustible materials, what is the minimum air space that is typically required? **
Answ** 1 inch
M1306.2
An appliance requires a minimum clearance without protection of 12 inches above the appliance
to combustible material. If 1/2-inch-thick insulation board with ventilated air space is used as
protection, the minimum clearance may be reduced to ______. ** Answ** 6 inches
M1306.2
A solid-fuel-burning appliance requires a minimum clearance without protection of 18 inches
from the side and back to combustible material. If 24 gage sheet metal with a ventilated air space
is used as protection, the minimum clearance may be reduced to ______. ** Answ** 12
inches
M1306.2.1 Table M1306.2
Where an appliance with an ignition source is located in the garage, the source of ignition shall
be located a minimum of ______ above the garage floor. ** Answ** 18 inches
M1307.3
A combustion air opening for a central furnace shall be unobstructed for a minimum distance of
______ in front of the opening. ** Answ** 6 inches
M1402.3
, The unobstructed total area of the outside and return air ducts or openings to a heat pump shall
be a minimum of ______ square inches per 1,000 Btu/h output rating or as indicated by the
conditions of the listing of the heatpump. ** Answ** 6
M1403.1
In order to permit the free drainage of defrost water, the supports or foundation for the outdoor
unit of a heat pump shall be raised a minimum of ______ above the ground. ** Answ** 3
inches
M1403.2
What is the maximum permitted operating temperature for a radiant heating system used on a
gypsum assembly? ** Answ** 125* F
M1406.5
Unless Listed and labeled for closer installation, a duct heater shall be located a minimum of
______ from a heat pump or air conditioner. ** Answ** 48 inches
M1407.3
The furnace register of a vented floor furnace shall be located a minimum of ______ from doors
in any position, draperies and other similar combustible objects. ** Answ** 12 inches
M1408.3 # 3
The access open through the foundation wall to a vented floor furnace shall have a minimum size
of ______. ** Answ** 18-inches by 24-inches
M1408.4
Where the lower 6 inches of a vented floor furnace is sealed to prevent water entry, a minimum
______ clearance shall be provided between the furnace and the ground. ** Answ** 2-inch
M1408.5 #3
In order for someone to service an appliance other than a room heater, a minimum working space
of______ inches deep by 30 inches wide shall be provided in front of the control side of the
appliance. ** Answ** 30
M1305.1
For the purpose of providing working space, a furnace or air handler located within a closet or
similar compartment shall be provided with a minimum of ______ clearance along the sides,
back and top of the appliance, with the total width of the enclosing space a minimum of
______wider than the furnace. ** Answ** 3 inches, 12 inches
M1305.1.1
A minimum ______ working space shall be provided along the front combustion chamber side of
a central furnace having a firebox open to the atmosphere. ** Answ** 6-inch
M1305.1.1
Where an appliance is installed in a compartment accessed by a passageway, the passageway
shall have a minimum unobstructed width of ______, but not less tham necessary to allow
removal of the largest appliance in the space. ** Answ** 24 inches
M1305.1.2
Where an appliance is installed in an attic, the clear access opening shall be a minimum of
______, but in no case less than necessary to allow removal of the largest appliance. **
Answ** 20-inches by 30-inches
M1305.1.3
Appliances suspended from the floor shall have a minimum clearance of ______ from the
ground. ** Answ** 6 inches
M1305.1.4.1
,Excavations for appliance installations shall extend a minimum depth of ______ below the
appliance with a minimum clearance of ______ on all sides except the control side. ** Answ**
6 inches, 12 inches
M1305.1.4.2
Where ventilated air space is used to reduce the required clearance between an appliance and
unprotected combustible materials, what is the minimum air space that is typically required? **
Answ** 1 inch
M1306.2
An appliance requires a minimum clearance without protection of 12 inches above the appliance
to combustible material. If 1/2-inch-thick insulation board with ventilated air space is used as
protection, the minimum clearance may be reduced to ______. ** Answ** 6 inches
M1306.2
A solid-fuel-burning appliance requires a minimum clearance without protection of 18 inches
from the side and back to combustible material. If 24 gage sheet metal with a ventilated air space
is used as protection, the minimum clearance may be reduced to ______. ** Answ** 12
inches
M1306.2.1 Table M1306.2
Where an appliance with an ignition source is located in the garage, the source of ignition shall
be located a minimum of ______ above the garage floor. ** Answ** 18 inches
M1307.3
A combustion air opening for a central furnace shall be unobstructed for a minimum distance of
______ in front of the opening. ** Answ** 6 inches
M1402.3
, The unobstructed total area of the outside and return air ducts or openings to a heat pump shall
be a minimum of ______ square inches per 1,000 Btu/h output rating or as indicated by the
conditions of the listing of the heatpump. ** Answ** 6
M1403.1
In order to permit the free drainage of defrost water, the supports or foundation for the outdoor
unit of a heat pump shall be raised a minimum of ______ above the ground. ** Answ** 3
inches
M1403.2
What is the maximum permitted operating temperature for a radiant heating system used on a
gypsum assembly? ** Answ** 125* F
M1406.5
Unless Listed and labeled for closer installation, a duct heater shall be located a minimum of
______ from a heat pump or air conditioner. ** Answ** 48 inches
M1407.3
The furnace register of a vented floor furnace shall be located a minimum of ______ from doors
in any position, draperies and other similar combustible objects. ** Answ** 12 inches
M1408.3 # 3
The access open through the foundation wall to a vented floor furnace shall have a minimum size
of ______. ** Answ** 18-inches by 24-inches
M1408.4
Where the lower 6 inches of a vented floor furnace is sealed to prevent water entry, a minimum
______ clearance shall be provided between the furnace and the ground. ** Answ** 2-inch
M1408.5 #3
