Laser Supply Air System.

[Kevin M. Adams]

Howdy Everyone,

I'm very excited to say I've purchased and received my very first laser system from epilog. It was a long time coming but a surprisingly simple process. We ended up going with an Epilog Zing 24 and couldn't be happier.

Now for the difficult part... I've searched the forums extensively for information about exhaust systems and set up. All in all, it seems to be a pretty simple undertaking. What I've not been able to find is any road maps on creating a closed system with exhaust AND supply air ducting. I have an idea in mind but I'd like to know if there are any better ones out there or if a successful supply is even possible. My hope is to isolate the air exhaust and allow our office to stay warm during the grueling Michigan winters. Rather than pumping it all out in a matter of minutes and reaching for my parka and bomber hat.

My own idea is to build a table with a supply ducting system built in. The plan is to build boots to cover the supply vents on the laser itself, a box underneath to connect the boots, and a port in the back to connect to a supply duct from outside. A 3in port will supply the air and a 4in exhaust will pull the vapor (and hopefully smell) back out and away from the house. Not a fully realized concept yet I know, but I wonder if this sparks any ideas or if something similar has already been done. Any photo's, links or HVAC tips would be a huge help.

Kind Regards,
Kevin

[Rich Harman]

Something else to consider is to use a pipe within a pipe to act as a heat exchanger. Warm up the incoming air a bit. I would be concerned about supplying the laser directly with such cold air.

[Kevin M. Adams]

Thanks Rich. I know some commercial shops use heat exchangers to temper the air a bit before it reaches the laser. I'm curious how necessary it would be. Would condensation be a real concern? Could it affect the optics to pump cold air into a room temperature machine at 600 cfm?

[Bill George]

What Rich is talking about is a double layer pipe. Inside pipe could be the exhaust, outside of the surrounding pipe is outside the building and pulls air in as needed. You really don't need a supply air fan as the exhaust fan pushing the air outside would draw in the makeup air. I see no reason why a 6 inch double wall gas vent pipe would not serve the purpose.

Yes condensation on the outside of the pipe, the part used to bring in outside air would be an issue, but some duct insulation wrapped around would help prevent. FYI they do make commercial air to air heat exchangers, you could look into that route.

FYI whatever air in CFM you are exhausting has to be made up in some way. Either by the double wall method (outside air vent) or though infiltration as cracks around windows and doors will provide. You are either heating or cooling that make up air by the last method.

Worst case, the makeup air comes out of the gas water heater or furnace vent pipe and CO kills someone.

[Kevin M. Adams]

I definitely understand the need for make up air vs. a CO leaking issue. What I don't understand is the affect of a double layer pipe on cold make-up air without some form of additional heating e.g. heated water coil, heated air, heat exchanger...

I guess the biggest question at this point isn't table design, but rather how to supply make up air directly to a laser machine while bypassing the office environment air completely.

[Dan Hintz]

Do not use outside makeup air vented directly into the machine. Condensation will quickly build when/where you least expect it and you will eventually short out your machine, dirty your optics, etc. If you feel the need to recirculate air (as I do), look at my (one and only) blog post (far righthand side of the name bar above this post) for a DIY filtration system. If you have the money, purchase a pre-made system,

[Kevin M. Adams]

If you don't mind Dan, would you happen to be able to explain in more detail how you would bring in tempered make-up air using a double layer pipe. I don't quite understand how it would work without some additional system to heat the air.

[Rich Harman]

The "hot" air is going out the inner pipe, the cold air coming in surrounds the "hot" inner pipe and thus gets warmed up while the outgoing air gets cooler. The pipe has to be a certain length for this to be effective. Too short and the incoming air will not be in contact with the "hot" pipe long enough to do much good. It is a cheap way to recover some heat that would otherwise be lost outside.

[David Somers]

Kevin,

If you look at the top right corner of Dan's title bar, over where it shows his Join date and Location, you will see a line that says "Blog Entries 1"
Click on the numeral 1 and you will be taken to a listing Dan did where he shows how to build an air filter for your laser at a reasonable cost. It would extract the smoke and fumes from your blower air and feed it back into the room. That way you are not sending your heated air outside using your blower.

The alternative is to purchase a much more expensive commercial air filter system. Which might be worth it to you. I might try this first though.

The other alternative is to borrow your wife's sewing machine, steal the electric blanket off the bed, and make an electric snuggy to wear in your shop in the winter. <grin>

Dave

[Dan Hintz]

If you don't mind Dan, would you happen to be able to explain in more detail how you would bring in tempered make-up air using a double layer pipe. I don't quite understand how it would work without some additional system to heat the air.

I won't describe such a system because it is not what you want/need (not to mention it would be overly complicated, and by the time you spent all of that money on all of the double-walled piping, you'd be halfway to a professional filter system, and paid for my DIY system several times over). Pulling in air directly from the outside is dangerous to direct vent into a machine for the reasons I just mentioned. It's like taking the air filter off of your Ferrari's engine just so you don't have to change it every 6 months. You spent a lot of money on that laser, so you should treat it appropriately.

[Rich Harman]

Just to be clear, the idea of recovering some heat through a double wall pipe does not include venting directly into the laser.

[Bill George]

Just to be clear, the idea of recovering some heat through a double wall pipe does not include venting directly into the laser.
You beat me to it. We usually dropped the OA supply pipe near the intake of whatever. We usually had either drawings or a spec book, from the engineer, sometimes not.

[Dan Hintz]

Just to be clear, the idea of recovering some heat through a double wall pipe does not include venting directly into the laser.

Venting would need to be in a really large room to avoid issues with high moisture levels in the air. Even in a small room there isn't ample time for the fresh air to mix with the ambient air and shed it's moisture... it will take longer, but you will slowly increase the humidity. Likely not to the point of condensation, I'll give you that, but you're just asking for trouble overall continually bringing that much moisture inside (think of what it would do to your house if you can't get rid of it immediately!). Dust/fume extractors pull a lot of CFM, so you will be continually keeping your environment nearly as saturated as the outside.

But it's the OP's decision, so until the farmer decides, this is all fighting between the cows...

[Rich Harman]

I'm not understanding Dan's opposition to this. To the best of my knowledge the vast majority of us exhaust directly outside. Air must come in to replace the outgoing air, and the only place that it can come from is outside. This is what most of us do and I for one have experienced no problems with high humidity in my shop - and I am in Western Washington. The only difference in this discussion is the idea to recover some of the heat from the outgoing air - making the incoming air just a bit warmer. Whatever issues there are with the moisture content in the replacement air, heating the incoming air is not going to add to them, in fact it will lessen them.

[David Somers]

Rich,

I may be misinterpreting Dan's thoughts (apologies if I am Dan), but I think he was objecting to outside air being brought directly into the laser from outside. A second 4 or 6 inch hose coming off your machine connected straight to outdoors. As your blower moves smokey air from the laser to the outside, air is replaced directly from outside through the second hose, through which you get cold, moist air brought straight into the laser. I think that was his concern. If your laser is replacing blown air from the ambient air in your shop the outside air that is seeping in to replace your blown out air has a chance to warm up some and the moisture coming in with it dissipates through the room so the impact inside the laser is much less.

His preference was not to blow the machine's air outside at all, but instead to run it through filters and feed it right back to the shop so it was not impacting your heating bill, and not sucking colder, moister air directly into the laser.

Does that make more sense?

Dave

[Rich Harman]

Rich,

I may be misinterpreting Dan's thoughts (apologies if I am Dan), but I think he was objecting to outside air being brought directly into the laser from outside.

I object to that as well. His reply included my quote where I said "...does not include venting directly into the laser."

Recycling the air through a filter system is not practical for everyone. I do mostly cutting on my laser, lots of smoke and sticky residue. To filter all that out would cost a fortune in filters. The next best thing would be to warm up the incoming replacement air by steeling some heat from the exhaust. What most people do is just exhaust outside and draw unheated replacement air from the outdoors - and they do so without experiencing any trouble.

[Bill George]

Coming from a commercial/industrial career in the HVAC/R field there are OSHA and EPA requirements for cutting and processing certain materials and its been too many years to recall what they are. Exhausting to the outside and bringing in outside air is pretty basic, if the make up air has been heated or cooled is the not the regulating authority's problem. Dan's concern was that dumping ice cold outside air directly into the laser would cause problems.

The make up does not need to be connected directly to the machine, just available. If a simple air to air or pipe inside the pipe works to some degree its better than nothing. But they do make heat wheels and other much more efficient methods to recover the heat or cooling from the exhausted air. It may not be cost effective to spend $10,000 to recover heat when Dan's method is available. If it meets OSHA or EPA requirements for all materials or not would remain to be seen.

[Dan Hintz]

I may be misinterpreting Dan's thoughts (apologies if I am Dan), but I think he was objecting to outside air being brought directly into the laser from outside. A second 4 or 6 inch hose coming off your machine connected straight to outdoors. As your blower moves smokey air from the laser to the outside, air is replaced directly from outside through the second hose, through which you get cold, moist air brought straight into the laser. I think that was his concern. If your laser is replacing blown air from the ambient air in your shop the outside air that is seeping in to replace your blown out air has a chance to warm up some and the moisture coming in with it dissipates through the room so the impact inside the laser is much less.

His preference was not to blow the machine's air outside at all, but instead to run it through filters and feed it right back to the shop so it was not impacting your heating bill, and not sucking colder, moister air directly into the laser.
This ^^^^^


I object to that as well. His reply included my quote where I said "...does not include venting directly into the laser."

Recycling the air through a filter system is not practical for everyone. I do mostly cutting on my laser, lots of smoke and sticky residue. To filter all that out would cost a fortune in filters. The next best thing would be to warm up the incoming replacement air by steeling some heat from the exhaust. What most people do is just exhaust outside and draw unheated replacement air from the outdoors - and they do so without experiencing any trouble.

I do a number of wooden plaques, and while it's not plywood and all of the nasty glue involved, the smoke from pine can be pretty "resiny" (my new word for the day). I do not spend a lot of money on filters. Instead, the first filter my exhaust hits is the cheap throwaway furnace filters you get 10 to a pack at your local fix-it store. With resinous woods, those filters can get clogged quickly, but at practically pennies a piece, I'm okay with swapping them out every few days during a busy period. I lose zero heat to the outside world by exhausting it back into the shop, and my Dylos air meter shows no discernible increase in particulate matter during processing.

[Rich Harman]

I think it is the smoke which requires expensive HEPA filters. The furnace filters that I have tried don't do much to remove smoke.

I think a big problem with filtering and exhausting back into the room with a DIY setup is that you need to be able to monitor it's effectiveness. Not just particulate but also harmful gasses, some of which are odorless. If it filters out 99% that means that you are continuously adding 1% as you use it. If you don't run it much then that is probably safe enough but I would not trust it to remove everything when running for hours at a time cutting the type of stuff that I do. I don't think you can be sure of it's effectiveness without expensive monitoring equipment.

Exhausting outside is safest. Nearly everyone does it, and does so without causing other troubles. Using a double wall pipe to recover some of the heat is not going to introduce any additional troubles. The only issue is you need to be sure that no exhaust mixes with the incoming replacement air. Something well within any good DIYer's abilities.

[Dan Hintz]

I think it is the smoke which requires expensive HEPA filters. The furnace filters that I have tried don't do much to remove smoke.

Correct... but it's not like I run the furnace filters on their own, I use them in front of my filtering system. The cheap furnace filters get rid of the resiny stuff so my main system doesn't get overwhelmed. The main system contains activated carbon and HEPA filtration, so I have everything covered. When I do really nasty stuff (which isn't often), I make sure the carbon is fresh... otherwise, I keep a watch on it and replace as necessary.