Section M1601 addresses heating and cooling equipment installation. Furnaces must have adequate combustion air and exhaust venting. Gas furnaces require sealed combustion vents to outdoors or open combustion air from interior spaces. Heat pumps provide both heating and cooling with high seasonal efficiency. Capacity must be sized for the building load, typically 100-125 percent of design heating load. Thermostats should be located in representative spaces for accurate temperature control. Return air paths must be adequate for proper circulation through the furnace.