NFI Gas Test- Use Flash Cards Questions With Complete
Solutions
If ACH is unknow (or greater than .40), the minimum required
volume of space providing combustion air is ____________
cubic feet per ____________ BTU/hr (page 53)
50 cubic feet per 1,000 BTU/hr (1,000/50 equals 20) => 20 is
used for the standard method.
If the room is not large enough and there is no adjoining room to
consider due to doors, 2 permanent openings from the room with
the appliance can work. Take the BTUs of the appliance and
divide by 1,000 to get the required sq in openings. So, if 40k
BTUs, how many square-inch openings are needed?
Note: divide by 500 if rooms are on different stories. Again, if
you can't get an area from adjoining rooms with no doors at the
same level,
40 sq inch for each opening
Each opening must have a minimum free area of 1 square inch
per 1,000 BTU/hr of the total input rating of all gas appliances
in the space, but not less than __________ square inches. (page
57)
100 square inches
Vents to the outside can be used to get to the proper combustion
air space needed. Take the BTUs per unit divided by 3,000
BTU/hr for a one opening method. This gives us the square inch
,opening needed. Multiply this by the percentage shortfall space.
9 square inch minimum. (page 58)
The two opening method for outside air vent calculation require
dividing the total appliance BTUs by 4,000. If through
horizontal ducts, you must have a least 1 square inch per
___________ BTU/hr. (Page 58)
2,000
Wood louvers are _______free area (page 59)
25 %
Metal grills ______ considered free (page 59)
75 %
Indoor source of air for adjoining rooms fact (need 2 openings):
1 inch squared per 1,000 BTU (12' of ceiling and 12" of floor)
100 inch square minimum.
Indoor source of air from different story (need 1 opening)
2 in shared per 1,000 BTU (through ceiling or floor)
Outdoor air source direct or vertical need 2 openings:
1 inch squared per 4,000 BTUs (12' of ceiling and 12" of floor)
Outdoor air source via horizontal ducts (need 2 openings)
1 inch squared per 3,000 BTUs (12' of ceiling and 12" of floor)
B Vent Termination Heights: Determine the slope of the roof
and use the table. Assume 12" run and then measure the height
to use the table (page 62). The table tells you the minimum
, height from the roof to the lowest _______________ opening of
the vent. (page 62)
discharge
B Vent (vent cap must be installed vertically) If closer than 8' to
the vertical wall, the vent must be ____ feet higher than
anything within 10'. (page 62)
2 feet
B Vent: Max rise to run ratio:
_________% of the vent height for single wall connector (12'
vertical means 9.75" max horizontal.
_________% for double wall B vent connector
Manufacturer may limit to 50%
75%, 100%,
Power Vent Locations:
Negative pressure Vent & Firebox: (1)
Negative pressure firebox, positive pressure vent (2)
Positive pressure firebox and vent (3)
1. Fan located at termination
2. somewhere between appliance and termination
3. Fan located under the firebox
Outdoor air opening size calculation: 60k BTU fireplace,
12x15x8 room
1: Calc room volume
2. Determine the required air volume (use standard method)
3. Determine % of air supplied by the room
Solutions
If ACH is unknow (or greater than .40), the minimum required
volume of space providing combustion air is ____________
cubic feet per ____________ BTU/hr (page 53)
50 cubic feet per 1,000 BTU/hr (1,000/50 equals 20) => 20 is
used for the standard method.
If the room is not large enough and there is no adjoining room to
consider due to doors, 2 permanent openings from the room with
the appliance can work. Take the BTUs of the appliance and
divide by 1,000 to get the required sq in openings. So, if 40k
BTUs, how many square-inch openings are needed?
Note: divide by 500 if rooms are on different stories. Again, if
you can't get an area from adjoining rooms with no doors at the
same level,
40 sq inch for each opening
Each opening must have a minimum free area of 1 square inch
per 1,000 BTU/hr of the total input rating of all gas appliances
in the space, but not less than __________ square inches. (page
57)
100 square inches
Vents to the outside can be used to get to the proper combustion
air space needed. Take the BTUs per unit divided by 3,000
BTU/hr for a one opening method. This gives us the square inch
,opening needed. Multiply this by the percentage shortfall space.
9 square inch minimum. (page 58)
The two opening method for outside air vent calculation require
dividing the total appliance BTUs by 4,000. If through
horizontal ducts, you must have a least 1 square inch per
___________ BTU/hr. (Page 58)
2,000
Wood louvers are _______free area (page 59)
25 %
Metal grills ______ considered free (page 59)
75 %
Indoor source of air for adjoining rooms fact (need 2 openings):
1 inch squared per 1,000 BTU (12' of ceiling and 12" of floor)
100 inch square minimum.
Indoor source of air from different story (need 1 opening)
2 in shared per 1,000 BTU (through ceiling or floor)
Outdoor air source direct or vertical need 2 openings:
1 inch squared per 4,000 BTUs (12' of ceiling and 12" of floor)
Outdoor air source via horizontal ducts (need 2 openings)
1 inch squared per 3,000 BTUs (12' of ceiling and 12" of floor)
B Vent Termination Heights: Determine the slope of the roof
and use the table. Assume 12" run and then measure the height
to use the table (page 62). The table tells you the minimum
, height from the roof to the lowest _______________ opening of
the vent. (page 62)
discharge
B Vent (vent cap must be installed vertically) If closer than 8' to
the vertical wall, the vent must be ____ feet higher than
anything within 10'. (page 62)
2 feet
B Vent: Max rise to run ratio:
_________% of the vent height for single wall connector (12'
vertical means 9.75" max horizontal.
_________% for double wall B vent connector
Manufacturer may limit to 50%
75%, 100%,
Power Vent Locations:
Negative pressure Vent & Firebox: (1)
Negative pressure firebox, positive pressure vent (2)
Positive pressure firebox and vent (3)
1. Fan located at termination
2. somewhere between appliance and termination
3. Fan located under the firebox
Outdoor air opening size calculation: 60k BTU fireplace,
12x15x8 room
1: Calc room volume
2. Determine the required air volume (use standard method)
3. Determine % of air supplied by the room
