A position should be selected where the detector will not be disturbed during the measurement period and where there is adequate room for the device. The measurement should not be made near drafts caused by heating, ventilating and air conditioning vents, doors, fans, and windows. Locations near heat, such as on appliances, near fireplaces or in direct sunlight, and areas of high humidity should be avoided. Because some detectors are sensitive to increased air motion, fans should not be operated in the test area. Forced air heating or cooling systems should not have the fan operating continuously unless it is a permanent setting.
Sound judgement is required as to what space actually constitutes a room.
Measurements made in closets, cupboards, sumps, crawl spaces, or nooks within the foundation should not be used as a representative measurement. 2.3 Initial Measurements 2.3.1 Rationale EPA recommends that a homeowner assessing the need for mitigation should first make a short-term test. The duration of short-term measurements can range from 48 hours to 90 days, depending upon the method used. However, attic fans intended to control attic and not whole building temperature or humidity should continue to operate. Combustion or make-up air supplies must not be closed.