Laser exhaust advice

[Mike Lush]

Hello all,

I've been watching this board for some time and have really learned a lot from the people involved, so thanks for all the info and advice I've already picked up.

Just having bought my laser (Epilog Helix) I was going to set it up in my garage and have been working towards that, but I have some room in my basement by the furnace room. What I was wondering is if anyone has hooked up their laser exhaust to the common house vent that your furnace, hot water heater is piped into? I have a 600cfm blower that I still plan on using. I thought this would be a better spot for the machine enviorment wise and it saves me from punching holes in my garage. It also saves me space in my work area for painting, assembly, etc. Any thoughts?

Take care,
Mike

[George M. Perzel]

Hi Mike;
Not sure this is a good idea and question whether it would not pass code as blower may cause back pressure on furnace/water heater exhausts (CO2), allowing deadly gas into house.
Best regards;
George
LaserArts

[Richard Rumancik]

If your idea is to "tee" into the tube which exhausts from the furnace/water heater, then it would not be a good idea. The blower from the laser will overpower the furnace/water heater pressure and prevent them from exhausting properly. It is very difficult to "share" an exhaust vent of any sort. (I was wanting to do this for my dryer and new basement bath vent but it won't work and is not generally allowed. One device will try to feed the other.)

Unfortunately, you will probably have to add a dedicated vent to the house. If there is any way to exhaust it up high (to the roof) I'd do that. But easier said than done.

[Mike Lush]

Thanks for the info on venting. I sort of suspected that was the case, but it's always good to ask.

[Joseph B. Chritz]

Mike ,
One thing to be aware of is 600cfm is moving a lot of air, and yes, you do need that much, but it has to come from some place. In a tight, well sealed home, there aren't many places for make up air to come from. Bathroom and kitchen vents could allow air to be sucked back into the home or maybe a furnace exhaust, and you don't want any exhaust gas to be brought back in. You may want to look at adding an air make up port close to your laser.

Google "air make up" for more info.

Joseph

[Ed Maloney]

OK - Now I'm worried. I'm planning to have the laser and a 650CFM blower in the basement about 10 feet from a water heater and the forced hot air furnace. Any ideas?

[Joe Pelonio]

You'll need an air intake larger than the 4" vent, preferably fresh air from the outside.

Otherwise leave the door to the basement open and allow the home air to come down. That should be sufficient, but you might actually want to contact your gas company and have them send a technician out to advise you. When it comes to carbon monoxide you have to be careful.

[Richard Rumancik]

The best way to check that you have not depresssurized your house would be to have a manometer connected between the outside of the house and your laser room. I can't tell you what pressure differential is safe, but your gas utility should be able to tell you. (I think the depressurization limit would probably be around the 5 pascals mark.)

A manometer (pressure gage that measures very low differential pressure) with a 1/4" hose going to the outside would tell you if you were getting into dangerous territory.

There is probably a vent for make-up air already in the house for the furnace. It might be large enough to service the laser and furnace/water heater/bath vents/kitchen vent etc. Otherwise another vent would be needed. I would have the manometer as there are lots of factors -including which way the wind is blowing. (Seriously - this is because the wind will help exhaust gas from the chimney.)

If you have an attic fan this will also cause depressurization.

I would also suggest that you get some carbon monoxide detectors for the house. Also, you might consider devices on the furnace and water heater that shut them off if they try to backdraft (i.e. air goes the wrong way, back into the house.)

If you consider these things and get some local HVAC advice you should be able to install the laser safely.

You might want to feed at least a partial makeup vent directly to the laser, as discussed elsewhere, if energy costs become a factor. I know the laser manufacturers ask for 400-600 cfm but I use a gate and only supply the air I need for the job. eg. I don't think you need 600 cfm for light engraving.

[Rob Bosworth]

Slide gates on the exhaust side of the system can make airflow easier to regulate. But a word of caution needs to be applied. There are systems made that the laser is cooled by air being sucked across the laser tube assy. by the exhaust blower. The manufactures have saved money by not adding muffin fans on some units to help remove the heat from the heat sinks that surround the laser. If you restrict the airflow to save on heat removal from your house, you just might end up with a shortened life on a laser tube because it operates to warm.

Heat is not a friend of electronics.

[Martin Reynolds]

Rob, are these the systems made where the laser tube is visible inside the cutting cabinet?

[Dave Jones]

Rob, I heard that mentioned on a forum a while ago, and am curious what lasers those are that do that. It seems like a really bad design since that would mean the residue from the exhaust would get stuck to the fins around the laser and would be a pain to clean.

[Mike Mackenzie]

Dave,

I believe that Epilog did that with some of there models.

[Martin Reynolds]

I've seen pictures of a system where the laser - no fins, a glass tube - sits on the back shelf of the cabinet, apparently about the same level as the lens.

[Joe Pelonio]

Epligos are cooled by the INCOMING air that vents out the exhaust, it's nice fresh air from the room. The intake vents are on the front as is the tube, so it's clean when it passes the tube and electronics.

[Dave Jones]

That makes a lot more sense.

I guess at some point they changed the design, because my Mini-24 has the laser tube in the back with a row of fans mounted over it and none of the intake/exhaust air flowing over it.

[Rob Bosworth]

Epilog made a machine called the TT, that had the laser tube mounted towards the front of the machine. Then they supplied venting to run the air from in front of the cabinet, over the laser, then into the engraving cabinet, then it exhausted the effluents from the laser processing out through the exhaust system. The way it was designed, it never really pulled "dirty" air over the heat sinks of the tube. But you need to have the exhaust on to move the air over the heat sinks that remove the heat from the laser. It is not a bad design, but it was pretty noisey listening to that exhaust system run all of the time. (Maybe not noisey to someone who hasn't burned his eardrum out sitting in front of the speakers while listening to INDAGODADAVIDA at a setting of 11 for too many years as a youngster.)

I have not seen enough of the low cost machines to know how many of these manufactures saved money by not having muffin fans, electronics and vents to keep tthe temp. of the laser constant. We only handle the "Professional" systems these companies make.

[Jim A. Walters]

Every glass tube I have seen has been water cooled.

[Ed Maloney]

I checked with our gas company here in NJ and gave them the details of the CFM. They did suggest that the simplest solution to was to crack a window open and have a temporary wall between the blower, the furnace and water heater.

[Mike Hood]

It's not a Laserpro or Pinnacle. My tube and power supplies are in a separately vented area below the table enclosure. No dust or dirt from cutting comes anywhere near it.