Quest HEPA Replacement Filter for Quest H5 Air Mover - 18 x 18 x 2.5

Quest H5 HEPA Replacement Filter, 18 x 18 x 2.5 and 99.97 Percent DOP Quest part 4031864 is the HEPA stage inside a Quest H5 air mover. It is rated at 99.97 percent DOP at 0.3 micron particle size. That 0.3 micron figure is worth understanding, because it is not the smallest thing the panel catches. It is the most penetrating particle size, the hardest diameter for media to trap. The EPA makes the same point about HEPA media. Particles both larger and smaller than 0.3 micron are captured with greater efficiency than that. So a filter rated at its worst case is doing better than 99.97 percent nearly everywhere else on the curve. The panel is 18 x 18 x 2.5 inches. Quest H5 Air Mover Filters: Pre-Filter First, HEPA Second The H5 runs two filters as standard, and the sequence matters. A pleated pre-filter, part 4031877, sits at the top and takes the coarse load. This HEPA panel sits behind it. The procedure is specific when the filter change light comes on. Pull the ducting, run the unit on high speed, and judge the airflow. Replace the pre-filter first. Change the HEPA only if the airflow has not recovered. Done that way the expensive panel lasts as long as it should, because the inexpensive one ahead of it is absorbing the debris. An optional carbon and potassium permanganate filter, part 4031878, handles gaseous contaminants. That one installs in place of the pleated pre-filter rather than alongside it. The same HEPA panel also carries the Phoenix name, another Therma-Stor brand, so the part number is the reliable match. Key Features Quest part 4031864: The part number to match, one panel per unit 99.97 percent DOP at 0.3 micron: Measured at the most penetrating particle size rather than the easiest one 18 x 18 x 2.5 in: The HEPA panel is the 2.5-inch one; the 1-inch panel in the same footprint is the pre-filter, part 4031877 Replace the pre-filter first: Run on high, judge airflow, change the pre-filter, and only then the HEPA Fits the Quest H5: Air mover unit part 4031450, and it takes one HEPA panel The unit tells you when: The H5 carries a filter change light rather than leaving the interval to a calendar Optional carbon stage: A carbon and potassium permanganate filter, part 4031878, replaces the pre-filter when gases are the problem Also made as a Phoenix filter: The same Therma-Stor panel appears under the Phoenix name, which is why the part number is the reliable match Technical Specifications Specification Value Quest part number 4031864 Type HEPA Rated efficiency 99.97% DOP at 0.3 micron Size 18 x 18 x 2.5 in Filters per unit 1 Compatible models Quest H5 air mover (unit part 4031450) Pre-filter part 4031877, 18 x 18 x 1, replaced first Optional carbon filter 4031878, installs in place of the pre-filter More on how Quest and Anden size their filters, what the MERV numbers mean and when each brand says to change them: Quest and Anden Filters: Sizes, Ratings and Replacement Timing.