These clearances must be permanently maintained. Clearances must also accommodate an installation's oil, electrical, and drain trap and drain line connections. If the alternate ventlflue connections are used additional clearance must be provided to accommodate these conditions Section IX, Vent Flue Pipe and Combustion Air Pipe for details.
NOTE: In addition to the required clearances to combustible materials, a minimum of 24 inches service clearance must be available in front of the unit.
A clearance of 24 inches at the rear of the unit is also recommended.
Thermostat Location
The thermostat should be placed apprOXimately five feet from the floor on a
oDrafts or dead spots behind doors, in corners, or under cabinets.
oHot or cold air from registers. o Radiant heat from the sun.
o Light fixtures or other appliances. o Radiant heat from a fireplace.
o Concealed hot or cold water pipes, or chimneys.
o Unconditioned areas behind the thermostat, such as an outside wall.
V.COMBUSTION & VENTILATION AIR REqUIREMENTS
!WARNING
. TO AVOID PROPERTY DAMAGE, PERSONAL INJURY OR DEATH, SUFFICIENT FRESH AIR FOR PROPER COMBUSTION AND VENTILATION OF FLUE GASES MUST BE SUPPLIED. MOST HOMES REQUIRE OUTSIDE AIR BE SUPPLIED INTO THE FURNACE AREA.
Improved construction and additional insulation in buildings have reduced heat loss by reducing air infiltration and escape around doors and windows. These changes have helped in reducing heating/cooling costs, but have created a problem supplying combustion and ventilation air for burning appliances.
Appliances that pull air out of the house (exhaust fans, fireplaces, clothes dryers, etc.) increase the problem by starving appliances for air.
House depressurization can cause back drafting or improper combustion of oil fired appliances, thereby exposing building occupants to combustion products that could include carbon monoxide and cause:
1.
2.Excessive humidity - heavily frosted windows or a moist feeling in the home.
3.Smoke from a fireplace will not draw up the chimney.
4.Flue gases that will not draw up the appliance vent pipe.
Combustion and Ventilation Air
Adequate provisions for combustion air, ventilation of furnace, and dilution of the gases must be made. When a furnace is installed in an unconfined space in a building, it can be assumed that infiltration will be sufficient to supply the required air.
If the furnace is installed in a confined space and combustion air is taken from the heated space, the supply air and ventilating air must be through two permanent openings of equal area. A confined space is U a space Whose volume is less than 50 cubic feet per 1000 BTU per hour of the combined input rating of all appliances installed in that space." One opening must be within 12" of the ceiling and the other within 12" of the floor. Each opening must have a minimum free area of at least 1 square inch per 1000 BTU per hour of total input rating of all appliances within the space but not less than 100 square inches.
If the furnace is installed in a space within a building of tight construction and air must be supplied from outdoors. In this case, one opening shall be within 12" of the ceiling and the other within 12" of the floor.
If vertical combustion ducts are run, each opening must have a free area of at least 1 square inch per 4000 BTU per hour.
If horizontal combustion ducts are run, 1 square inch per 2000 BTU per hour of the total input of all appliances is required.
6
