This was in a townhouse where they installed the furnace and water heater in a closet off of the upstairs master bedroom. The closet space was only about 2’x8’x8’. At first I was going to write it up for not enough combustion air and for being off a sleeping area. There was another metal pipe that ran into the closet from the attic above, which at the time of the inspection, I wasn’t sure what it was. I now realize that is was probably for combustion air to be pulled from the attic above. Is this application okay then? The fourth picture shows the pipe which runs next to the water heater and then terminates at about 2’ off the floor. The last picture shows the furnace/water heater flue in the middle (yes I caught the combustible clearance) and the combustion air pipe on the right going through the ceiling. There was no access to the attic and it did not appear to come out of the roof. Thanks.
G2406.2 (303.3) Prohibited locations.
Appliances shall not be located in, or obtain combustion air from, any of the following rooms or spaces:
Sleeping rooms.
Bathrooms.
Toilet rooms.
Storage closets.
Exceptions:
Direct-vent appliances that obtain all combustion air directly from the outdoors.
Vented room heaters, wall furnaces, vented decorative appliances and decorative appliances for installation in vented solid fuel-burning fireplaces, provided that the room meets the required volume criteria of Section G2407.5.
A single wall-mounted unvented room heater equipped with an oxygen depletion safety shutoff system and installed in a bathroom, provided that the input rating does not exceed 6,000 Btu/h (1.76kW) and the bathroom meets the required volume criteria of Section G2407.5.
A single wall-mounted unvented room heater equipped with an oxygen depletion safety shutoff system and installed in a bedroom, provided that the input rating does not exceed 10,000 Btu/h (2.93 kW) and the bedroom meets the required volume criteria of Section G2407.5.
Appliances installed in an enclosure in which all combustion air is taken from the outdoors, in accordance with Section G2407.6. Access to such enclosure shall be through a solid weather-stripped door, equipped with an approved self-closing device.
From what I see in the photo and your description the combustion air provision is not proper based on current IRC standards. Should be two ducts one terminating within 12 inches of the ceiling and one terminating within 12 inches of the floor.
SECTION M1703
ALL AIR FROM OUTDOORS
M1703.1 Outdoor air.
Where the space in which fuel-burning appliances are located does not meet the criterion for indoor air specified in Section M1702, outside combustion air shall be supplied as specified in Section M1703.2.
M1703.2 Two openings or ducts.
Outside combustion air shall be supplied through openings or ducts, as illustrated in Figures M1703.2(1), M1703.2(2), M1703.2(3) and M1703.2(4). One opening shall be within 12 inches (305 mm) of the top of the enclosure, and one within 12 inches (305 mm) of the bottom of the enclosure. Openings are permitted to connect to spaces directly communicating with the outdoors, such as ventilated crawl spaces or ventilated attic spaces. The same duct or opening shall not serve both combustion air openings. The duct serving the upper opening shall be level or extend upward from the appliance space.
M1703.2.1 Size of openings.
Where communicating with the outdoors by means of vertical ducts, each opening shall have a free area of at least 1 square inch per 4,000 Btu/h (0.550 mm2/W) of total input rating of all appliances in the space. Where horizontal ducts are used, each opening shall have a free area of at least 1 square inch per 2,000 Btu/h (0.275 mm2/W) of total input of all appliances in the space. Ducts shall be of the same minimum cross-sectional area as
the required free area of the openings towhich they connect. The minimum cross-sectional dimension of rectangular air ducts shall be 3 inches (76 mm).
M1703.3Attic combustion air.
Combustion air obtained from an attic area, as illustrated in FigureM1703.2(3), shall be in accordance with the following:
The attic ventilation shall be sufficient to provide the required volume of combustion air.
The combustion air opening shall be provided with a metal sleeve extending from the appliance enclosure to at least 6 inches (152 mm) above the top of the ceiling joists and ceiling insulation.
An inlet air duct within an outlet air duct shall be an acceptable means of supplying attic combustion air to an appliance room provided that the inlet duct extends at least 12 inches (305 mm) above the top of the outlet duct
in the attic space, as illustrated in Figure M1703.3.
The end of ducts that terminate in an attic shall not be screened.
Thanks for the replies and thanks for the code reference Chuck. I agree…not enough openings. “The same duct or opening shall not serve both combustion air openings” (M1703.2). In this case, they used the same pipe and from everything I could see, it was not an inlet air duct within an outlet air duct installation. And besides, either way, the openings do not meet the required 1 square inch per 4,000 Btu input. Along with that, the door was not weatherstripped with a self-closing device and there was certainly not 12" of total clearance space on the sides of the furnace. I’ll write it up as not meeting todays safety recommendations for combustion air. Thanks for the help!
