Author Topic: Creating negative pressure venting a dryer  (Read 4727 times)

Offline islandtees

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Creating negative pressure venting a dryer
« on: May 19, 2015, 08:15:18 PM »
If you vent your dryer in a AC environment it creates negative pressure. Those with AC how do you vent your dryer and where is the replacement air coming from?  From inside the building your pumping a lot of AC out and warm air in. I notice our dryer moves a lot of air from the dryer and we will be installing AC units in our new building. Just want to see how your doing it.


Offline Inkworks

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Re: Creating negative pressure venting a dryer
« Reply #1 on: May 19, 2015, 10:06:43 PM »
We crack a door and just accept the loss of cool air and introduction of hot air. You can get make-up air that runs through a heat exchanger or into your A/C but the cost is so high for those systems that it hasn't made sense to me as of yet. We're adding a 2 piece A/C system that I picke up used at a bargain price to help the central A/C, the two piece will be aimed at the hottest spot to work in the shop, and basically be for cooling down people in it's flow, rather than trying to cool the whole shop. We also run a portable swamp cooler in the same manner, pointed right at operators, as a bonus it also helps humidify the dry A/C air.
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Offline islandtees

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Re: Creating negative pressure venting a dryer
« Reply #2 on: May 22, 2015, 08:35:09 AM »
No one else has ac?

Offline Screen Dan

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Re: Creating negative pressure venting a dryer
« Reply #3 on: May 22, 2015, 10:02:39 AM »
No one else has ac?

That seems like some space-aged billionaire's fairy tale to me.  We'd need to install massive drop ceilings...get three or four times the AC capacity we currently use...and there's a good chance I'm grossly underestimating that.  Maybe 10 to 20 times, considering the heat the two dryers put off.

We've never even considered it, honestly.  Any time a new guy in the shop asks about why we don't have AC in the summer time we just laugh.  The bay doors are opened as wide as they can go, man.

Offline Frog

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Re: Creating negative pressure venting a dryer
« Reply #4 on: May 22, 2015, 10:14:50 AM »
No one else has ac?

I seem to remember Pierre running a cool(ed) shop.
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Offline bimmridder

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Re: Creating negative pressure venting a dryer
« Reply #5 on: May 22, 2015, 10:41:36 AM »
We run two Sprint 2000 ovens for three autos and a total of 10 flashes. Yep, we have A/C. I just put on all my safety gear, knowing I'm going to get blasted. We are in Iowa, and there are days in the middle of winter that the A/C may kick on. Even with doors cracked and roof hatch open. We strongly believe that keeping employees fresh and comfortable, especially when they are working 10+ hours, is to the benefit of all involved. So yes, we have doors and roof open to bring new air in.
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Offline blue moon

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Re: Creating negative pressure venting a dryer
« Reply #6 on: May 22, 2015, 12:44:44 PM »
We run two Sprint 2000 ovens for three autos and a total of 10 flashes. Yep, we have A/C. I just put on all my safety gear, knowing I'm going to get blasted. We are in Iowa, and there are days in the middle of winter that the A/C may kick on. Even with doors cracked and roof hatch open. We strongly believe that keeping employees fresh and comfortable, especially when they are working 10+ hours, is to the benefit of all involved. So yes, we have doors and roof open to bring new air in.

similar here. doors open, AC is just taking the edge off. It gets to high 80's here every now and then, but for the most part low 80's is where we are. Less humidity makes a big difference too.
We have a ceiling fan that sucks the air out (very small one) and hoods over the end of the dryer to catch the really hot stuff. It is not a very good system, but it's better than nothing. My guess is we are spending $800 or so per month to AC. It does make a huge difference in the quality of work environment. . .

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Offline jsheridan

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Re: Creating negative pressure venting a dryer
« Reply #7 on: May 22, 2015, 01:07:13 PM »
hook up a second vent pipe from the outside that attaches to the air inlet of the dryer.

Draws outside air, not inside.
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Offline Gilligan

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Re: Creating negative pressure venting a dryer
« Reply #8 on: May 22, 2015, 01:18:17 PM »
We run two Sprint 2000 ovens for three autos and a total of 10 flashes. Yep, we have A/C. I just put on all my safety gear, knowing I'm going to get blasted. We are in Iowa, and there are days in the middle of winter that the A/C may kick on. Even with doors cracked and roof hatch open. We strongly believe that keeping employees fresh and comfortable, especially when they are working 10+ hours, is to the benefit of all involved. So yes, we have doors and roof open to bring new air in.

similar here. doors open, AC is just taking the edge off. It gets to high 80's here every now and then, but for the most part low 80's is where we are. Less humidity makes a big difference too.
We have a ceiling fan that sucks the air out (very small one) and hoods over the end of the dryer to catch the really hot stuff. It is not a very good system, but it's better than nothing. My guess is we are spending $800 or so per month to AC. It does make a huge difference in the quality of work environment. . .

pierre

This cat right here has the doors wide open when it's 50 outside and the heater running full blast.

I'm from Louisiana... that just don't make sense! :)

Offline blue moon

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Re: Creating negative pressure venting a dryer
« Reply #9 on: May 22, 2015, 01:23:04 PM »
We run two Sprint 2000 ovens for three autos and a total of 10 flashes. Yep, we have A/C. I just put on all my safety gear, knowing I'm going to get blasted. We are in Iowa, and there are days in the middle of winter that the A/C may kick on. Even with doors cracked and roof hatch open. We strongly believe that keeping employees fresh and comfortable, especially when they are working 10+ hours, is to the benefit of all involved. So yes, we have doors and roof open to bring new air in.

similar here. doors open, AC is just taking the edge off. It gets to high 80's here every now and then, but for the most part low 80's is where we are. Less humidity makes a big difference too.
We have a ceiling fan that sucks the air out (very small one) and hoods over the end of the dryer to catch the really hot stuff. It is not a very good system, but it's better than nothing. My guess is we are spending $800 or so per month to AC. It does make a huge difference in the quality of work environment. . .

pierre

This cat right here has the doors wide open when it's 50 outside and the heater running full blast.

I'm from Louisiana... that just don't make sense! :)

yeah, as mentioned before, we are having some issues with exhausting properly so the doors are wide open. While the dryer was completely in the AC'd space, we had the outside air piped in as John suggested.

Make up air is the way to go though. You pipe the outside air to the side/bottom of the dryer hood and pull the air out form the top. This way the air being sucked out is coming from outside.

pierre

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Offline Gilligan

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Re: Creating negative pressure venting a dryer
« Reply #10 on: May 22, 2015, 01:33:28 PM »
What about for us in very humid places.

If we pull in outside air we would be pulling in a cup of water an hour or something (totally made that up) :)

Offline islandtees

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Re: Creating negative pressure venting a dryer
« Reply #11 on: May 22, 2015, 10:34:51 PM »
No one else has ac?

That seems like some space-aged billionaire's fairy tale to me.  We'd need to install massive drop ceilings...get three or four times the AC capacity we currently use...and there's a good chance I'm grossly underestimating that.  Maybe 10 to 20 times, considering the heat the two dryers put off.

We've never even considered it, honestly.  Any time a new guy in the shop asks about why we don't have AC in the summer time we just laugh.  The bay doors are opened as wide as they can go, man.
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« Last Edit: May 22, 2015, 10:41:08 PM by islandtees »

Offline Maxie

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Re: Creating negative pressure venting a dryer
« Reply #12 on: May 24, 2015, 03:12:15 AM »
Get a new dryer, I looked at a Adelco at FESPA and the outside metal was cool, the excess heat was exhausted.     I'm sure most new dryers will be similar.
I once worked in a shop where we built walls around the dryer so it was in a seperate room, just the front of the belt stuck out and above the belt was a window so we could see the dryer.
We had baskets for catching the shirts so nobody was working behind the dryer.
We'd wheel the baskets into the AC section when they were full.
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Offline Binkspot

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Re: Creating negative pressure venting a dryer
« Reply #13 on: May 24, 2015, 08:18:06 AM »
Like John said duct in outside air to the dryer.

I have been to a few shops where they simply cool the "hot spot". The AC is ducted to the load/unload area and the end of the dryer with defusers blowing directly to those areas. The return is picked up in a low spot in the shop where the air would be cooler to begin with. Most of these shops run with the bay doors open also. So basicly your creating cool down statins where the bulk of the work is being done.

Offline sben763

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Re: Creating negative pressure venting a dryer
« Reply #14 on: May 24, 2015, 10:02:19 AM »
I have a duct right under dryer.  Originally had it up by the hood portion but it was then letting some smoke/vapors in the shop.  This also helps just cycle outside air to the dryer and directly back outside thus reducing the heat loss and over working the AC. I have a dryer vent hood inside so that when the dryer fan is shut off it closes off.