I have a 8 gallon wet-dry vac that I want to put inside a cabinet. Roughly 24" x 24" x 29". The hose and cord will come through a hole in the side. The door will be a simple overlay style with a latch.
I'm trying to save space but also keep the noise down.
Do I need to add some holes in the back for exhaust? The cabinet certainly won't be air tight, but is the door and hose hole enough?
Thanks.
A vac blows out the same amount of air it sucks in so no, your proposal is insufficient.
It certainly needs an exhaust hole. If it will be used continuously for any length of time, I would wonder about it overheating.
Unless you intend to open the door when it's running or the hole for the
2" hose is 8" in diameter, my guesstimate is "No!" You're going create back pressure, just like shoving a potato in an exhaust pipe.If you really want to put it in a cabinet and cut down noise, I would experiment with a downward vent or some other form of baffling/muffler in the cabinet design. First thing that I would try would be to build a simple box 24" square by 29" high, turn on the vacuum and lower the box over it, leaving maybe 2" between the bottom of the box and the floor. If that muffled the sound sufficiently, I would then remove one side of the box, replace it with the door you describe, and cut my holes for the hose. Then, instead of just letting the cabinet sit on the floor, I would attach four legs (simple 2x4's with the tops bevel cut so they don't act so much as a shelf to catch dust and crap) to the corners of the box to keep it 2" off the floor. That will provide for a more or less unrestricted air flow from the vacuum's exhaust.
There are a few other things you could do to accomplish the same thing and maybe even make it quieter. You want to lengthen the path of the exhaust flow without restricting it. The bottom line is that "what goes in, must come out"
Volume of air in = volume of air out. If you don't have enough open space you will make the motor work harder trying to work against the back pressure, you will lose some efficiency on the suction and will build up heat in the cabinet. not a big deal for 15 seconds but for a long time it will be.
Put it in the cabinet to save space but open the door to run it.
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An 8" equivalent hole could easily be accomplished with rectangular opening in the upper portion back of the cabinet. 3" x 24? would be bigger tha n a 8" hole with hose in it. Bigger would be better, but then the noise reduction goes down.
Seems to me that an opening at the top, where the vac actually exhausts, would be more efficient than an opening at the bottom. I could even add a baffle to direct the air out of the top opening so it didn't go straight up to the top of the cabinet.
Lengthening the path is not an option. The shop is too small. The vac will go into a cabinet that I'm building for the miter saw. I actually have a 1.5 g allon ShopVac in the existing cabinet, but it fills up too quickly and is a pain to empty. Foam filter, hard to clean, very messy. I'll be building a bigger cabinet t o fit the 8 gallon vac.
Leaving the back panel 3" to 4? short and leaving a gap between the wall and the cabinet should work.
Thanks to all.
ughly 24" x 24" x 29". The hose
ple overlay style with a latch.
ainly won't be air tight, but is
to fit the 8
You might consider an Oneida dust deputy (or equivalent) to reduce the hass le of emptying the shop vac...
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Efficient design could make it work but making the box not much bigger than the vac precludes that. Make a box of, let's say 3/4" ply, and line it with sound-absorbing foam (the fire-retardant sort) and make sure that the inner dimensions are such that there are a few inches of space around each side of the vac. The exhaust should probably be four to six times the area of the hose and to minimize the noise it should be in the form of a snorkel facing downward and lined with the foam too. This should make things nice and quiet but will mean a lot of work and the result will not be small. Far better IMHO is to simply buy one of the quieter European vacs and damn the cost.
If it chokes it down, you know you need a port somewhere. Personally, I would think the cabinet doors would act like an air check valve when the vac is on. Meaning the air pressure would push the doors out a but to let the air out.
You could always make your own one-way vent by putting a hole in the cabinet and tacking a rubber flap across it. Most cars have this system somewhere on the vehicle for when the heater/AC blower fan in on. On pick-ups, it's behind the seats on the back panel wall.
That is why I mentioned the simple overlay door. Plywood on a face frame is certainly not going to be airtight. A loose latch would allow it open a little, although more sound will escape. That's why any opening that I might need would be in the back of cabinet. I'm sure the difference would be minimal, but just as easy to do, maybe even easier. Just cut the back panel 3-4" short.
I'm not sure I see the point of that. When the vac is on the flap will open and the air will escape. When the vac Is off, the flap will close and, well, and *what*?
What would be the advantage of a one-way vent over just an opening in the back to let the exhaust air escape? What would I be trying to keep out?
Check this...
I was thinking of critters and dirt. If you're not concerned with dust, bugs, and such getting in, then sure, just a hole. Doesn't have to be big. Like others have said, it only needs to be the size of the exhaust hole on the vac.
Cheap aesthetics maybe?
Or drill two or three 3/4" holes in the back. My electronics cabinet has a number of these with friction-fit small metal round vents.
I don't think I'll concern myself with the outside of the vac getting dusty. ;-)
Critters? Like the raccoon that keeps eating the cat food in the garage? So far he hasn't found my shop.
A short back panel will serve just fine. Thanks again.
You need more than that to vent properly. If you have one outlet equal to the size of the hose, the velocity of the exhaust will be equal to the velocity of the inlet. Put your hand over the outlet on the vac and see if a couple of 3/4" holes is enough not to make back pressure.
Thanks. I like the baffle system. I'll have to see if I can do something like that. I have to be exact with my height since this is a miter saw cabinet and the saw's table needs to be the same height as the workbench next to it. I don't know if I have room for the double shelf.
Maybe I can do something on the side.
BTW...his electrical skills suck compared to his woodworker skills. No Romex connector where the extension cord goes to the switch box and his switch is upside down. No connector/strain relieve is a dangerous situation.
There you go. Very interesting design. Derby, my thought with the bottom exhaust was to accomplish this baffling. This is much better.
Build the cabinet, add holes later if there is not enough venting.
y 24" x 24" x 29". The hose
overlay style with a latch.
y won't be air tight, but is
It all depends on where the cabinet is located. If its on an outside wall, vent it like you would a clothes dryer, i.e., run a hose from the "blowing side" through the wall. A small vent to allow for air circulation for coo ling the motor and a bit of sound absorbing material and you are home free.
If its on an inside wall, you are pretty much done for. Because you will h ave to have enough ventilation to cool the motor and enough exhaust capabil ity to keep from seriously cutting into you CFM . You can line the cabinet with sound absorbing material, but all those holes are going to let a lot of noise out.
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