Makeup air from the house to the shop.

[Ron Gosnell]

Howdy,

I am getting my shop ready to install my new laser. It's on the truck heading this way. It's a Thunder Laser Mars 90 130 watt 900x600. I am installing a harbor freight exhaust fan up in the attic venting through the roof.
My shop is 16 x 18 insulated and has a through the wall window AC/Heater. It works really well as is. When I run my exhaust though I am pretty sure that it wont keep up. The shop is attached to the house. I am thinking of running a duct through the attic between the shop and a bathroom. It's about a 15' run. I will gut the bath vent and attach the duct to it. I'm pretty sure I can attach a 10" duct to it and a backdraft adaptor. So the question is do you think a 10" duct would be big enough to supply the makeup air. Do you think vacuum alone would pull enough air or would an inline duct fan be better ? Should the vent be placed close to the laser or let it pull from across the room.

I appreciate any input, suggestions or comments

Gozzie

[Bill George]

Ron, here is the problem the air you remove has to be replaced and you already know that. But the Makeup Air needs to come from outside not another part of the building. So for heating you could run your duct for the makeup air across the attic and then to the outside. It would pick up some heat that way, wrong for AC. For AC I have seen it proposed but never in the real world, a underground duct, (think metal culvert ) down where the earth temperature is cool supplying cooling air to a space. It would need to be set up so as to not collect water and the vent going above ground would need a cap, but its tossed out for consideration.

[Joe Pelonio]

I simply keep a window open when running, regardless of the weather, but I do prefer it cold to hot so a cool breeze even in freezing weather is OK. That window is about 10' from the laser, 8' from where I sit at the computer, and that setup has always worked fine, 8 years now.

[Kev Williams]

My shop is in my basement (1200 sq ft x 7' tall), then directly up the stairs and straight ahead is my 'new' garage shop, about 22' square. The rest of the upstairs is blocked by a folding door just beyond the front door entry.

Don't know how many cubic feet that is, but at any given time I have 3 HF "green" blowers, 1 HF "red" blower, and a HF "big green" blower running all at the same time. If the CFM figures are right, that's around 4000 cubic feet of air per minute they're sucking out of this place.

In 12 years of using them, they always do their job, and I've never noticed any difference one way or another when they're on or off...

[Bill George]

Kev, I am trying to remember where you are located but if you took even 900 cfm out of my shop when it was below zero F you would notice! When its that cold I simply postpone a few days.

[Ron Gosnell]

My 16 x 18 shop is pretty small and I think the exhaust would evacuate the air fairly quickly.
We live in Arkansas with high temps and humidity.
It's a Chinese tube and I understand that they are pretty temperature sensitive so I am concerned about quality of make up air.
I have a chiller to keep the tube cool but then there is the condensation factor too.
Am I being too paranoid ?

Gozzie

[Keith Winter]

Ron if you are concerned about condensation you can buy a 1000-1500 Sq ft dehumidifier from home Depot / Lowe's for $200 or less

[Ron Gosnell]

A dehumidifier is a great idea.
I think I'll wait and see how it all pans out.
It's a pretty simple project and it wouldn't take a few hours to complete if needed.
Thanks for the input everyone.

Gozzie