Exhaust Hookup


I work with a glow forge in a windowless studio but there is a vent for an ac. This is the hook up that I figured out (see pic). Does anyone see an issue with running my air conditioner and glow forge at the same time during hot summer months?

Would appreciate any insight!


What do you mean a vent for the AC?

Most air-conditioning systems are closed loops meaning if you inject all your smoke into the AC line it should just be pushed back out all around your house. Which would be … bad.

Did you mean a vent for the dryer? That’s less bad but still not good. There are a few reasons why not but I won’t get into them until you reply.


I mean vent for an AC - see image

My landlord approved and installed this vent for me.


Oh, A room AC unit. Got it.

On the back of your AC unit there should be two hoses, one for intake and one for exhaust. If so and you’re hooking into the exhaust I think you’re on the right track but I do worry a little bit about backflow.

When you’re pushing all the air out of your Glowforge into the exhaust line it’s got to go somewhere and there is some resistance heading to the outside, so some air will flow back up towards your AC unit.

In theory your AC unit is a closed loop circuit to the outside where it’s pulling in coolish air from outside and then exhausting the heated air from the AC unit. I’m not sure what negative effect might be on the AC unit if you try to push laser exhaust past it. Laser exhaust tends to leave residue on almost everything, and you really don’t want to get deposits on your heat exchanger inside the AC unit. At the very best it will reduce efficiency and at worst it might actually damage it I suppose.

Add to that… We’re not sure exactly how well sealed all of the hoses and couplings coming from the AC unit to the outside door. You might experience some leakage of exhaust fumes into your workspace.

In short… Ideally you would have a dedicated exhaust for your laser. This might work but I suspect there will be downsides.

Oh, I forgot to address whether or not you can run them both at the same time. Having something hooked into the AC close loop circuit… When your AC is running it will either try to push air into your Glowforge or pull air from it, depending on where you’re hooked into the AC loop. If you’re in the exhaust you can expect hot air to be pushed out through your Glowforge. If you’re hooked into the intake to the AC you could expect room to be drawn in through your Glowforge. At the very least I would install a blast or two to try to limit what can flow where I would try to avoid running them at the same time.


Thank you for the detail response! I appreciate it! I don’t have very many options being in nyc. I will not run them both at the same time.


actually, my room unit is not a closed loop like that. it pulls air in through vents on the side of the unit, cools it and vents hot air out through the vent hose and cold air into the room through the vents on the top.

you definitely don’t want to be pulling outside air into your portable AC unit to cool, because then you’re starting with much hotter air than pulling air from inside. kinda like running the AC in your car, if you use internal air, it’s colder and more efficient than pulling outside air.

this, of course, is different than true central air, which does pull air from outside (in my personal case, from our crawl space and through the filter).


I was going on this page:

And some of the images seem to show two hoses.

I reserve the right to be wrong on this or any other matters past present and future :slight_smile:


it’s possible there may be some closed loop systems. my LG portable AC in my office/studio is definitely getting it’s intake air from the two vents on the left/right sides of the unit.

FWIW, i’ve never seen a portable AC with two vent hoses using a closed loop system, but i’s very possible they exist. i think non closed loop is the standard, but i could be wrong.


I believe the recommendation from Glowforge regarding the exhaust run length is to limit it to 8 feet and limited 90-degree turns. With what I can see of the exhaust run, it looks extensive enough to need an inline booster fan. One installed at the top of the run would eliminate any potential backflow also.


Same with my Frigidaire & Haier units I had in my garage shop.


Unless you add blast gates to isolate both the GF and AC units, you’re going to get combustion products blowback from the GF into your interior space AND hot AC exhaust blowing back into your GF (and then into your interior space)… The blast gates might allow you to operate them one at a time. Maybe.


Aha I finally actually read that page. I know, who does that? Anyway it indeed has an intake and exhaust, for all the efficiency reasons I suspected it would.

It doesn’t change any of my thoughts on whether or not it’s a good idea to hook this up to the AC exhaust… If at all possible I would be trying to make a completely separate exhaust for the Glowforge.

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Welcome, it’s a really fun tool.
You’ve already received some great advice here - definitely add an in-line booster fan and blast gates. There’s a free file on this forum for a blast gate you can make out of acrylic but I found the $10 one from Rockler to be super easy to use.

Additionally, check your electrical situation just in case you’re ever tempted to run both at the same time. I have a newish but modest electrical panel in my garage and if I try to run both the Glowforge and portable AC at the same time the breaker always trips within a minute.

Same - I vent mine through a window adapter that came with it and added a hole in same adapter for my GF exhaust. Have never had any issues with smoke getting mixed up with my AC airflow.


Is that where you’re too tired to do adult stuff with your date but so is she so you end up napping together while watching a movie? :grin::joy::joy: I couldn’t help myself


or at least, not good…

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