Venting Through Ceiling

So I’m thinking I’ll cut a hole in the ceiling slightly larger than the ducting. I’ll attach the inline fan close to the end of the ducting and create a vent in the eaves for the outtake.

I’ll attach an extension cord to the fan and run it through the same hole in the ceiling as the ducting. Both my Forge and the fan will be plugged into a power strip, so when I flip the switch on the strip, both the Forge and the fan come on.

When the Forge is up and running, I’ll cut a cover for the hole in the ceiling to make it look less ugly that there’s a hose and extension cord coming out of it.


you may not care, but it’s probably against code to run extension cords in the wall / ceiling like that. (not saying you shouldn’t do it, just something to think about, especially if you ever need a permit for something else).

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I have a few details in my shop that wouldn’t pass a home inspection, but present zero hazard (to me). The area is an unfinished bedroom, and all of the equipment including the laser I consider a temporary installation.
When the house eventually goes up for sale, none of it will remain.
I did finally connect the florescent lights to the Romex with a metal junction box instead of dangling wire nuts. :grimacing:


When I did my shop, the electrician told me that code requires ground wires to be bonded (by screw or equivalent) to every junction/outlet box. Even if it’s plastic.

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This may be what you mean by:[quote=“brooklyntonia, post:21, topic:8570”]
create a vent in the eaves
It could be connected to a hole in the eave with something like this, not loose in the eave.
If you have a path to the exterior then you should not need an additional in-line fan.

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Not quite the case. The GF exhaust fan is only rated to reliably exhaust the machine with a maximum 10’ of flexible 4" diameter hose and 2 90 degree bends. Longer than that and the machine may not exhaust properly and in the OP’s case up into the ceiling and into the eaves is almost certainly likely to exceed the GF design limit.

@takitus (I think) or @karaelena have long run exhaust systems setup with booster fans (placed at the terminus so as not to leak through the run).



Thanks for letting me know that.
It looks like they recommend a 20’ effective length (10’ plus two 90 degree bends which calculate to 5’ each)

I had a previous post where I compared this to a dryer duct.

I am concerned about fire safety with some of the exhaust runs.
I would be careful about using flex where it cannot be easily cleaned.
Debris laden exhaust can sometimes catch fire.
There might be special in-line booster fans for debris laden exhaust (I have looked and can’t find any).
A simple in-line exhaust fan will be the exact location where debris will collect (as well as in flex duct).
I am not sure of the flammability of the particles coming out of the Glowforge (as they are already burnt), or the temperature of the exhaust.
I know that it is different than a dryer and dryer lint, but not sure how different.

Nothing shameless about show and tell…we all do it here unabashedly. Great job on your backsplash!

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I can imagine that when cutting lightweight paper, some small unburnt bits may get caught up in the air assist and be drawn into the exhaust stream.

When I have cleaned my window screen and the exhaust port on the Glowforge, there are visible bits of stuff and not just ash or powder. Not much, but it’s there.

That was precisely what I was planning, though I was concerned about the Forge fan being strong enough to push the air the extra length. I thought an additional fan may be needed if it’s going to have to travel more than the 8’ that the included hose will reach.

I wonder what could build up after a few years of use.
If the hidden lengths of duct are smooth metal, one of those pipe-cleaner looking brushes could be run through it. Not so easy with hidden flex duct, an impossible if an in-line fan is in the way.

Maybe if the fan was at the end (in your case near the eave), and could be accessed there and removed for cleaning?
Another option could be to install some sort of access panel at the fan so that it could be removed for cleaning of the fan and ducts.

I may be sounding overly cautious, but fires in dryer ducts, for example, are very common.
This exhaust, although not the same as dryer exhaust, does have debris.
Particles being pushed this way can generate static sparks, and if there is a build-up of un-burnt “fuel”, can spell disaster.

The best long-term solution might be to get an air-filter and/or put it near a window until the filter arrives, rather than jerry-rigging some sort of long venting contraption.


The debris in the ducting has already been burnt…lol. Very different than fabric lint which is highly flammable.


I would be careful about that. I don’t want to be the downer of this thread, but if the water heater still uses the vent CO could back up into the :glowforge: vent.

My opinion is why risk your life or your house? The air-filters are not that expensive considering.

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I am probably being overly cautious, but others have indicated that it is not totally ash.

If you look at my setup, anything that doesnt make it to the roof and out, falls back into the part that I can open and empty…


I wondered what the T junction was for. How often does it fill up?


I’m curious about that too.

it should always be at the very end if you’re using a supplemental booster. this avoids putting too much pressure - and thus leaks - into the vent hose / pipe.