The Quest H5 Pre-Filter Is the One You Change First
Quest's H5 manual gives this panel a job and a sequence. It is the top filter in a two-stage stack, part 4031877, and the HEPA sits underneath it. When the filter change light comes on the manual says to pull the ducting, run the unit on high, and look at the airflow. Change this panel. Then check again before touching the HEPA. That sequence is the whole economic argument for a pre-filter. This one is inexpensive and easy to swap. The panel it protects is not. Every load of coarse debris this catches is a load the HEPA never has to hold.
Sizing the H5 Pre-Filter, and the Two MERV Numbers in Circulation
The size is settled: 18 x 18 x 1 inch, a quarter the depth of the 2.5-inch HEPA in the same footprint. The grade is less tidy. Quest's own H5 manual describes it as 25 to 30 percent efficient per ASHRAE 52.1-1992, MERV-7, pleated fabric. Every distributor listing, ours included, calls it MERV 8. Both numbers are in circulation for the same part number, so we publish both rather than pick one. Either way the grade is coarse on purpose. A pre-filter that captured fine particulate would blind quickly and starve the HEPA of airflow, which is the opposite of the job. Quest also offers a carbon and potassium permanganate filter, part 4031878. It goes in this slot instead when gases rather than dust are the problem.
Key Features
- Quest part 4031877: The part number to match for a single panel, which is how these are stocked
- Change this one first: Quest's manual sets the sequence: pre-filter first, then the HEPA only if airflow has not recovered
- 18 x 18 x 1: Same footprint as the HEPA panel behind it at a quarter of the depth, which is how the two are told apart
- MERV-7 or MERV 8, both published: Quest's H5 manual says 25 to 30 percent efficient per ASHRAE 52.1-1992, MERV-7; distributor listings say MERV 8
- Coarse on purpose: A pre-filter that caught fine particulate would blind fast and starve the HEPA of the airflow it needs
- Protects part 4031864: The HEPA panel it sits above costs many times more, and lasts far longer behind a fresh pre-filter
- Fits the Quest H5: Quest lists the air mover as unit part 4031450
- Carbon alternative: Quest's part 4031878 installs in this slot instead when gases rather than dust are the issue
Technical Specifications
| Specification | Value |
|---|---|
| Quest part number | 4031877 |
| Type | Pleated fabric pre-filter |
| Grade, Quest H5 manual | MERV-7, 25-30% efficient per ASHRAE 52.1-1992 |
| Grade, distributor listings | MERV 8 |
| Size | 18 x 18 x 1 in |
| Filters per unit | 1 |
| Compatible models | Quest H5 air mover (unit part 4031450) |
| Sits above | HEPA panel, Quest part 4031864, 18 x 18 x 2.5 |
| Carbon alternative | Quest part 4031878, installs in place of this panel |
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.