Dryer venting - main chamber + intake/outake

[ZooCity]

So I know it's considered a no-no to run your in/outtake exhaust into the main stack vent of a dryer but it would be pretty convenient if that was an option for us.  Is this considered bad procedure due to the fact that the main stack could get clogged and push exhaust air from the middle chamber back out the in/outtake vents?  If so, couldn't you mitigate that risk by sticking to a rigid cleaning schedule?

I have a bid in to rework our hvac so that we have a separate run across the whole shop to tie in spot venting.  Before pulling the trigger I wanted to check into this option.  Our all electric texair pushes a lot of airflow out the main stack from the middle forced air section and our only real need is for some additional exhaust over the IR bump panels and in/out take at front/rear. It's mostly shirt fumes but I feel like there could be a touch of dc in there and that's no good.  General ventilation (big ass exhaust in one corner of the shop, our whole space is only 1750sf) takes care of it right now but I want it to be as good as possible.

I feel like it would be kosher to tie the intake/outake (with booster fans) into the main stack provided you never let enough lint build up in the run to back it up.  Am I way off here and missing something?

[Baron265]

You should get the advise of a local HVAC source. They'll know formulas and codes. That being said, my two cents is that the main stack diameter will have to increase to accomodate the additional cubic feet of air flow. As for the lint, filter it at the source. There's probably a HVAC filter system that can be added inline just above each hood.

Good luck!

[ZooCity]

I should have mentioned the main stack is 12"! 

My HVAC said it would be fine from the air flow side of things but I had heard not to risk this so we didn't at the time.  I'm not a cheap ass but it could save us quite a few thou to use the existing stack for this.

[Printficient]

Call you know who.  904-343-0848

[sweetts]

Just try it and if it works your gold,  if not then you need to spend some more $$$


RT Screen Designs
www.rtscreendesigns.com

[Evo]

I posted about this to the M&R board. I'm currently trying (unsuccessfully) to convince the new shop I work at to re-pipe the dryer vent hoods. (It's a Sprint)

Hood at the entrance has no pipe, the exit one has a 6" pipe that "Y's" into the main pipe. The main goes from 12" at the dryer, then expands to 14" at the "Y", then goes back down to 12" about 20' up at the ceiling. (stupid, right?)

NONE, and I mean NONE of the excess heat or fumes/smoke from the dryer goes up that 6" pipe. If anything the heat seems to be blowing down from the main pipe into the shop.

Hoffman said the main pipe should be 18" to handle the main exhaust and the hood exhaust. I'd think he's right.

My understanding is you can combine the vent hood pipes together and have them exhaust separately from the main, with a blower at each hood to help evacuate the fumes/heat.

Hoffman also said M&R makes an extended, powered hood that is an option for the Sprints, if you are printing with some really gnarly stuff.

[ZooCity]

I agree with Rich overall on that.  I might have my guy run the numbers like baron said and, if good, take sweetts route and try hooking up the in/outtake vents to a Y, see how it goes and if it doesn't consistently get 'er done then go ahead with the full install for spot ventilation and tie into that instead.  You have to run the hood vents in either case.  We got a bid for doing this on the cheap, using a lot of existing, and it's still a few thou to have dedicated exhaust ran even in our small shop.

It's really the outtake area that needs it, that last IR panel bumps the shirts and I really think 99.9% of the fumeage is shirt, not ink.  The shirts are fully discharged before they hit the outtake bump, the panel just ensures they're pulled up to 340-375 before exiting.  Maybe that bump isn't needed but I like to know we're hitting ink mfg recommendations for the high end temp on wb and dc.

[Evo]

I agree with Rich overall on that.  I might have my guy run the numbers like baron said and, if good, take sweetts route and try hooking up the in/outtake vents to a Y, see how it goes and if it doesn't consistently get 'er done then go ahead with the full install for spot ventilation and tie into that instead.  You have to run the hood vents in either case.  We got a bid for doing this on the cheap, using a lot of existing, and it's still a few thou to have dedicated exhaust ran even in our small shop.

It's really the outtake area that needs it, that last IR panel bumps the shirts and I really think 99.9% of the fumeage is shirt, not ink.  The shirts are fully discharged before they hit the outtake bump, the panel just ensures they're pulled up to 340-375 before exiting.  Maybe that bump isn't needed but I like to know we're hitting ink mfg recommendations for the high end temp on wb and dc.

You want to take WB inks up to the correct temp as early as possible and hold it there for the recommended duration to fully cure. Say, 340 for 2-3 minutes, depending on the ink. It's not like plastisol where once you hit the temp your good, so the final bump might be useless for wb/discharge.