Wood Return Air Grills

1. Do the grills rattle?
As part of our assembly process, the slats go through interlocking center bars, which give the grills excellent stability and dampens any tendency of the slats to vibrate.

2. Is there sufficient air flow?
Yes, if the grill is sized correctly. Our wood grills have approximately 12% less clear area when compared to the same size metal grill.

3. Can they be installed in existing openings?
Yes, if the opening is large enough. In some cases changing out the same size grills, wood for metal, you may need to make some alterations. The wood grills require the openings to be ¾" wider and ½" higher than the grill size (which is also the filter size).

If the wood grill is 24" x 24", then the rough opening would be 24 ¾" x 24 ½".

4. Are the grills difficult to install?
No. Once the hardware is installed on the grill and the opening is sized correctly you should have no difficulty installing the grill.
See illustration for installation instructions.

5. Is the hardware difficult to install?
Installation of the hardware is made simple with the pre-punched holes on the outer side of the frame. The holes are staggered so the correct piece of hardware will fit in its proper place. No measuring required - just screw the pieces in. The instruction sheet which comes with each grill will show how and where each piece is placed.
See illustration for installation instructions.

6. Will the grills warp?
The interlocking of the parts in the assembly process helps to retard any tendency for the grill to warp.

7. How durable are the grills?
The wood grills are constructed out of select material. We have had grills in homes and businesses for the last few years and all are doing very well. If the wood grills are installed properly and the openings are correctly sized they will give you many years of excellent service.

8. Will the wood grills whistle?
We have tested our wood grills in a wind tunnel using a blower motor from a 3 ½ ton air conditioning unit. We started with a 24" x 24" wood grill and a 24" x 24" metal grill. Using the same blower we restricted the size of the opening until we heard the metal grill whistle - the wood grill did not. We continued to reduce the size of the wood grill, but it never did whistle or vibrate.

9. Will wood grills pick up moisture?
Our wood return air grills will not pick up any more moisture than the rest of your finished furniture, moldings and doors in your home or office. The wood grills must, of course, be finished (painted or stained and sealed).

10. How is the grill size determined?
Our wood return air grills are sized by your unit air requirements. One hundred square inches of clear area per ton of air conditioning seems to provide a good air flow to the unit. Our wood return air grills average approximately 52% clear area and metal grills average approximately 64% clear area, a difference of 12%. If you use the premise that each ton of air conditioning (12,000 BTU) requires 400 cubic feet of air per minute with a return side velocity of approximately 350 feet per minute (a comfortable velocity in the home) then a 3 ½ ton unit requires 350-400 clear square inches. A filter 24" x 30" = 720 sq. in. x 52% = 374 clear square inches, which should be adequate for this 3 ½ ton unit.

11. How is the rough opening for the wood return air grill determined?
The rough opening of our wood return air grills is determined by taking the grill size (which is also the filter size) and adding ¾" to the width and ½" to the height.

20" x 30" grill requires a rough opening of approximately 20 ¾" x 30 ½".

12. Is it difficult to remove the grill from the opening in order to change the filter or clean the grill?
The wood return air grill is held in place by means of four clips (2 on each side) and four tension screws in the rough opening (2 on each side). The grill should snap in with ease, but if it is too tight or loose, adjust the tension screws in the rough opening as needed. Screw them in for a looser fit or out for a tighter fit. To insert the grill in the opening, place the grill in opening and apply pressure to the frame area of the grill (not the slats nor the outer area of the trim). To remove the grill, pull firmly on the slats near the top of the grill and the grill will snap out.

13. What species of woods are available?
Grills are available in the following species. Not all sizes are available in every species for immediate shipment.
  • White Poplar
  • Red Oak
  • Cypress
  • Walnut
  • Cherry
  • Mahogany

    White Poplar and red oak are available in all sizes.
    Cypress, walnut, cherry, mahogany available in most sizes.

    14. What size grills are available?
    There are 72 different sizes of wood return air grills.

    15. Are the wood grills available prefinished?
    Our wood return air grills come unfinished, so you may finish them to meet your color or stain requirements.

    16. Can the grills be installed in the ceiling?
    We do not advise using the wood grills in the ceiling. Hardware for ceiling installation should be available later this year.

    17. Static Pressure
    If the return air grill is sized correctly and your system is properly designed and everything is setup according to plan, you should measure a static pressure of 0.5 w.c.

    Stephan Manufacturing
    MADE IN U.S.A.