Vent reducer

[Adam Less]

First off, thanks to those who gave advice on an earlier thread re: how to actually get my new 6040N Chinese laser into the basement as it wouldn't fit through the doors.

Now that I solved that problem I have another question. The ducting for the laser to the blower and out from the blower to the wall is 6" not the 4" I was expecting. Not a problem, except I have to put a vent cap on the outside wall and we have mice in the area where I live. This means I have to have a pest guard on that vent cap. The challenge is that all the vent caps with pest guards are 4" not 6". they don't make 6" ones with pest guards. Don't ask me why.

So, my two choices are 1) make a makeshift pest guard for a 6" vent cap, which might be fine or 2) get a reducer and reduce the ducting some point before the wall from 6" to 4" so I can use the standard 4" caps with guards, which is easy to do.

My question is two-fold. First, will it make a real difference to anything if I reduce the ducting down and second, if so (or I guess, even if not) where should I be reducing, from the laser to the blower, somewhere along that ducting, or from the blower to the wall?

Any thoughts?

[Keith Winter]

You will bottle neck it, and more strain on your blower and decrease your flow. Real world though I'm not sure you will notice too much on your size machine. Give it a shot, it might work just fine. If it ends up being too smokey then expand your pipe is what I'd do.



First off, thanks to those who gave advice on an earlier thread re: how to actually get my new 6040N Chinese laser into the basement as it wouldn't fit through the doors.

Now that I solved that problem I have another question. The ducting for the laser to the blower and out from the blower to the wall is 6" not the 4" I was expecting. Not a problem, except I have to put a vent cap on the outside wall and we have mice in the area where I live. This means I have to have a pest guard on that vent cap. The challenge is that all the vent caps with pest guards are 4" not 6". they don't make 6" ones with pest guards. Don't ask me why.

So, my two choices are 1) make a makeshift pest guard for a 6" vent cap, which might be fine or 2) get a reducer and reduce the ducting some point before the wall from 6" to 4" so I can use the standard 4" caps with guards, which is easy to do.

My question is two-fold. First, will it make a real difference to anything if I reduce the ducting down and second, if so (or I guess, even if not) where should I be reducing, from the laser to the blower, somewhere along that ducting, or from the blower to the wall?

Any thoughts?

[Gary Hair]

The exhaust fans we use are more efficient when there is less airflow so I would restrict the line before the fan instead of after.

[Mike Null]

I don't think it'll make a noticeable difference. I've had mine that way for years and I'm very happy with the exhaust. Besides the screen there is a damper on the dryer vent piece I'm using so neither bugs nor cold air enter.

[Rich Harman]

The exhaust fans we use are more efficient when there is less airflow so I would restrict the line before the fan instead of after.

I am skeptical of the assertion that restricting the intake makes them more efficient. I would agree it would use less power that way, but it would also move less air. I would recommend fabricating your own pest guard for the 6" if it something you can do without much trouble. That way your blower will be moving the most amount of air. If it is too much trouble to do that then I would put the reducer at the very end so that when you decide you want more airflow you won't have to change anything except the vent.

The greater the length of the narrow tubing, the greater the losses. Restricting before the blower means that everything after it is the narrower tubing. For best efficiency, meaning most amount of air moved per unit power, you want friction losses to be as low as possible - that requires larger diameter tubing for as much of the run as possible.

[Clark Pace]

I 3d printed mine. Perhaps you can get that done

[Gary Hair]

I am skeptical of the assertion that restricting the intake makes them more efficient. I would agree it would use less power that way, but it would also move less air.

What I meant to say was that the motor has less load and the fan itself is moving more efficiently, not that the airflow was more efficient, as you said it would move less air using less power.

[Lance Hensley]

This is a 6" with guard I found on Amazon (Speedi-Products EX-WCHD 06 6-Inch Diameter Heavy Duty Wall Cap, Gray). It works great for me.

[Keith Winter]

First off, thanks to those who gave advice on an earlier thread re: how to actually get my new 6040N Chinese laser into the basement as it wouldn't fit through the doors.

Now that I solved that problem I have another question. The ducting for the laser to the blower and out from the blower to the wall is 6" not the 4" I was expecting. Not a problem, except I have to put a vent cap on the outside wall and we have mice in the area where I live. This means I have to have a pest guard on that vent cap. The challenge is that all the vent caps with pest guards are 4" not 6". they don't make 6" ones with pest guards. Don't ask me why.

So, my two choices are 1) make a makeshift pest guard for a 6" vent cap, which might be fine or 2) get a reducer and reduce the ducting some point before the wall from 6" to 4" so I can use the standard 4" caps with guards, which is easy to do.

My question is two-fold. First, will it make a real difference to anything if I reduce the ducting down and second, if so (or I guess, even if not) where should I be reducing, from the laser to the blower, somewhere along that ducting, or from the blower to the wall?

Any thoughts?

Btw making a make shift pest guard is very easy. Just buy some 1/2 or 1/4" chicken wire bend it to fit into the tube and screw it in with metal screws.

[Rich Harman]

I 3d printed mine. Perhaps you can get that done

You 3d printer a reducer/restrictor, or a vent outlet with pest guard? If the latter, do you have a picture to show?

[Wilbur Harris]

I kinda like Keith Winter's idea....